Because of its tenacious rhizomatous habit Sorghum halepense has earned a bad reputation as a weed of cultivated fields. Worse than this, under certain circumstances its tissues contain hydrocyanic acid and are a positive danger to stock.
Endrezzi (in Bot Gaz. 119: 1. 1957) considers that Sorghum halepense arose as a segmental allotetraploid from a cross involving Sorghum propinquum (2n=20) and a member of Subsect. Arundinacea (2n=20). Sorghum propinquum extends from China to the Malay Peninsula, but does not occur in India, and is the only diploid Halepensia.
The following description of Johnson grass provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for identification are available (e.g., [72,93,94,96,111,149,176,194]).
Morphology: Johnson grass is a nonnative, warm-season perennial [49,71,122,184,201]. It is usually rhizomatous, but is a highly variable species with many ecotypes [96]. It may grow as an annual in hot, arid climates and at the northern limits of its range [61,197,198]. Johnson grass rhizomes form a dense, tangled, tough sod [204]. Rhizomes serve as carbohydrate-storing and regeneration organs [6]. Most rhizomes occur in the top 7.9 inches (20 cm) of soil, although rhizomes in soft, deep soil may extend deeper [42,96]. Rhizomes vary in size from a few inches to several feet in length, and in thickness from 0.25 to 0.75 inch (6.4-19 mm) [86]. Leaves and aboveground stems (culms) are coarse [149]. Culms are 1.6 to 4.9 feet (0.5-1.5 m) tall. Total plant height may reach 12 feet (3.7 m) during flowering [5]. The inflorescence is a 4- to 24-inch (10-60 cm) open panicle. Spikelets of Sorghum species are paired: 1 is sessile and perfect; the other spikelet is pedicelled and staminate. Spikelets are 4 to 7 mm in length. There are about 35 to 350 spikelets per panicle, depending upon ecotype. Lemmas are cilate; they may be awnless or have short (1-15 mm), sometimes twisted awns that aid in seed dispersal [49,70,93,122,184,194,196,201]. Seeds are about 2 mm long [149].
Physiology: Several physiological characteristics of Johnson grass aid in its spread. Mature Johnson grass plants are moderately drought resistant [6] and salt tolerant [207]. Johnson grass produces toxins (see Toxicity) that may be allelopathic [96,135,196].
Johnson grass is native to the Mediterranean region of Europe and Africa, and possibly to Asia Minor. Worldwide, its range as a weed extends from 55° N to 45° S in latitude [96,128]. It was widely introduced in North America, Europe, Africa, and southwestern Asia [184], and was also introduced in Brazil, Argentina [155], and northern Australia [78]. In North America it occurs in southern Ontario south through all the contiguous United States except Maine [72,109,206] to the Rio Grande Delta region of Tamaulipas and the Cape region of Baja California Sur in Mexico [204]. Johnson grass also occurs in Hawaii and the Caribbean [109].
In the United States, Johnson grass was introduced in South Carolina from Turkey around 1830. William Johnson, whom the plant is named after, established Johnson grass along the Alabama River in the 1840s as a forage species, and Johnson grass spread rapidly across the South [14,149,170,182]. Johnson grass is now widely escaped from cultivation in much of the United States. It is most invasive in the Southeast, although it is widespread in central California and New Mexico [122,128,206]. Johnson grass is not persistent in the Pacific Northwest, upper northern Great Plains, extreme northern portions of the Great Lake states, the Northeast [70,110,132,194], or in Arizona, Colorado, and Utah [111,200,201]. Plants database provides a state distributional map of Johnson grass.
Johnson grass occurrence is not well documented for all plant communities where it may occur. The following classification lists are not restrictive, but include plant communities where Johnson grass is a documented species.
Fire adaptations: Johnson grass is likely to survive fire by sprouting from rhizomes (review by [71]). Because Johnson grass rhizome depths can reach 8 inches (20 cm) or more below ground [42,96], Johnson grass is likely to survive even severe fire. Rhizome expression in Johnson grass is variable (see Asexual regeneration); therefore, this adaptation may not be applicable to all populations.
Little documentation is available on postfire regeneration of Johnson grass from seed. As a seed banking species that produces abundant, readily dispersed seed (see Sexual regeneration) that establishes well in open, disturbed sites (see Seedling establishment/growth), it is likely that Johnson grass is capable of postfire seedling establishment from both on- and off-site sources. Germination of Johnson grass seed was not affected by exposure to temperatures of 200 °F (90 °C) and 400 °F (200 °C) for 120 seconds. However, germination was dramatically reduced following exposure to 660 °F (350 °C) and was eliminated after exposure to 800 °F (430 °C) and higher [131]. See [131]. See IMMEDIATE FIRE EFFECT ON PLANT for details of this study. More information is needed on postfire establishment potential of Johnson grass.
Fuels: Johnson grass litter reportedly remains on the ground all winter [104]. Johnson [107] provides a simple technique for estimating ratios of live:dead plant materials in Johnson grass.
FIRE REGIMES: As of this writing (2004), there was no published information on how North American FIRE REGIMES affect Johnson grass. In riparian and other areas where Johnson grass is highly productive, Johnson grass may promote fire spread by increasing fine fuel loads above historical levels. Studies are needed on the fire ecology of Johnson grass in North American.
The following table provides fire return intervals for plant communities and ecosystems where Johnson grass may be important. Find further fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".
Community or Ecosystem Dominant Species Fire Return Interval Range (years) maple-beech-birch Acer-Fagus-Betula > 1,000 silver maple-American elm A. saccharinum-Ulmus americana < 35 to 200 sugar maple A. saccharum > 1,000 sugar maple-basswood A. saccharum-Tilia americana > 1,000 [195] California chaparral Adenostoma and/or Arctostaphylos spp. < 35 to < 100 bluestem prairie Andropogon gerardii var. gerardii-Schizachyrium scoparium 117,144] Nebraska sandhills prairie A. gerardii var. paucipilus-S. scoparium < 10 bluestem-Sacahuista prairie A. littoralis-Spartina spartinae 144] silver sagebrush steppe Artemisia cana 5-45 [92,122,148] sagebrush steppe A. tridentata/Pseudoroegneria spicata 20-70 [144] basin big sagebrush A. tridentata var. tridentata 12-43 [160] Wyoming big sagebrush A. tridentata var. wyomingensis 10-70 (40**) [192,210] coastal sagebrush A. californica < 35 to < 100 saltbush-greasewood Atriplex confertifolia-Sarcobatus vermiculatus < 35 to < 100 desert grasslands Bouteloua eriopoda and/or Pleuraphis mutica 5-100 [144] plains grasslands Bouteloua spp. 122,144] blue grama-needle-and-thread grass-western wheatgrass B. gracilis-Hesperostipa comata-Pascopyrum smithii 122,144,159] blue grama-buffalo grass B. gracilis-Buchloe dactyloides 122,144] grama-galleta steppe Bouteloua gracilis-Pleuraphis jamesii < 35 to < 100 blue grama-tobosa prairie B. gracilis-P. mutica 144] sugarberry-America elm-green ash Celtis laevigata-Ulmus americana-Fraxinus pennsylvanica 195] paloverde-cactus shrub Cercidium microphyllum/Opuntia spp. < 35 to < 100 blackbrush Coleogyne ramosissima < 35 to < 100 northern cordgrass prairie Distichlis spicata-Spartina spp. 1-3 [144] beech-sugar maple Fagus spp.-Acer saccharum > 1,000 [195] California steppe Festuca-Danthonia spp. 144,178] black ash Fraxinus nigra 195] cedar glades Juniperus virginiana 3-22 [79,144] creosotebush Larrea tridentata < 35 to < 100 Ceniza shrub Larrea tridentata-Leucophyllum frutescens-Prosopis glandulosa 144] yellow-poplar Liriodendron tulipifera 195] Everglades Mariscus jamaicensis 134] wheatgrass plains grasslands Pascopyrum smithii 122,144,148] pine-cypress forest Pinus-Cupressus spp. 10] shortleaf pine P. echinata 2-15 shortleaf pine-oak P. echinata-Quercus spp. < 10 slash pine P. elliottii 3-8 slash pine-hardwood P. elliottii-variable < 35 sand pine P. elliottii var. elliottii 25-45 [195] South Florida slash pine P. elliottii var. densa 1-5 longleaf-slash pine P. palustris-P. elliottii 1-4 [134,195] longleaf pine-scrub oak P. palustris-Quercus spp. 6-10 [195] pitch pine P. rigida 6-25 [38,90] pocosin P. serotina 3-8 pond pine P. serotina 3-8 loblolly pine P. taeda 3-8 loblolly-shortleaf pine P. taeda-P. echinata 10 to < 35 sycamore-sweetgum-American elm Platanus occidentalis-Liquidambar styraciflua-Ulmus americana 195] galleta-threeawn shrubsteppe Pleuraphis jamesii-Aristida purpurea < 35 to < 100 eastern cottonwood Populus deltoides 144] mesquite Prosopis glandulosa 124,144] mesquite-buffalo grass P. glandulosa-Buchloe dactyloides < 35 Texas savanna P. glandulosa var. glandulosa 144] black cherry-sugar maple Prunus serotina-Acer saccharum > 1,000 [195] California oakwoods Quercus spp. 10] oak-hickory Quercus-Carya spp. < 35 northeastern oak-pine Quercus-Pinus spp. 10 to 195] oak-gum-cypress Quercus-Nyssa-spp.-Taxodium distichum 35 to > 200 [134] southeastern oak-pine Quercus-Pinus spp. 195] coast live oak Q agrifolia 2-75 [74] white oak-black oak-northern red oak Q alba-Q. velutina-Q. rubra 195] canyon live oak Q chrysolepis <35 to 200 blue oak-foothills pine Q douglasii-P. sabiniana 10] northern pin oak Q ellipsoidalis 195] Oregon white oak Q garryana 10] bear oak Q ilicifolia 195] California black oak Q kelloggii 5-30 [144] bur oak Q macrocarpa 195] oak savanna Q macrocarpa/Andropogon gerardii-Schizachyrium scoparium 2-14 [144,195] chestnut oak Q prinus 3-8 northern red oak Q rubra 10 to < 35 post oak-blackjack oak Q stellata-Q. marilandica < 10 black oak Q velutina < 35 live oak Q virginiana 10 to195] interior live oak Q. wislizenii 10] cabbage palmetto-slash pine Sabal palmetto-P. elliottii 134,195] blackland prairie Schizachyrium scoparium-Nassella leucotricha < 10 Fayette prairie S. scoparium-Buchloe dactyloides 195] little bluestem-grama prairie S. scoparium-Bouteloua spp. < 35 tule marshes Scirpus and/or Typha spp. < 35 southern cordgrass prairie Spartina alterniflora 1-3 [144] baldcypress Taxodium distichum var. distichum 100 to > 300 pondcypress T. distichum var. nutans 134] elm-ash-cottonwood Ulmus-Fraxinus-Populus spp. 52,195] **meanJohnson grass is most common on disturbed sites such as ditch banks, roadsides, fields, and "waste places" [93,111,149,200]. It occurs on all soil textures [86], with best growth occurring on silty bottomland soils [3,86]. On old bottomland fields of the Mississippi and Yazoo rivers, Mississippi, Johnson grass cover is greatest on silty-clay loams [3].
Moisture regime: Although Johnson grass occurs in wet to dry habitats in its native range in southern Europe [184], it is generally restricted to wet or mesic sites in the United States [72,93,201]. It is most common in warm, humid southern climates that receive ample summer rainfall. Johnson grass is a facultative wetland species, frequently occurring on floodplains [18,19]. Johnson grass patches are often extensive along canals and irrigation ditches [96]. In arid sites such as Organ Pipe Cactus National Monument, Arizona, Johnson grass establishes mostly in wet locations including washes, drainages, and stream edges [61,177].
Elevational ranges of Johnson grass in several states are:
Arizona below 6,000 ft (1,800 m) [111] California below 2,600 ft (800 m) [93] Nevada 2,000-5,000 ft (600-1,500 m) [201] New Mexico 3,500-6,000 ft (1,100-1,800 m) [122] Utah 2,800-5,000 ft (850-1,500 m) [201]Fire likely top-kills Johnson grass [86], while most rhizomes probably survive most fires.
Fire scarification appears to have no effect on rate of seed germination, and very high temperatures kill Johnson grass seed. In the laboratory, there were no significant differences in rates of germination between unheated Johnson grass seed and seed heated to 200 °F (90 °C) and 400 °F (200 °C) for 120 seconds; mean germination rate was 52%. Mean germination rate dropped to 17% for seed exposed to 660 °F (350 °C) and to 0% for seed exposed to 800 °F (430 °C) and 1000 °F (538 °C) for 120 seconds [131].
Impacts: Johnson grass is an important agricultural weed that causes serious economic losses [35,80,96,112]. Based upon its nearly worldwide distribution and adverse effect on the global economy, it is described as 1 of the world's worst weeds [96]. Johnson grass was recognized as 1 of the 6 most damaging weeds in the United States by the turn of the 20th Century, and was the 1st weed targeted by the USDA for research on control methods [128]. Johnson grass causes millions of dollars in lost agricultural revenue annually in the United States [129]. For example, Johnson grass infestations reduce yields in Louisiana sugarcane (Saccharum officinarum) fields by 25-50% [128]. In 1 study, 7 tons/acre (16 t/ha) of Johnson grass rhizomes were produced on a Louisiana sugarcane field [86]. Johnson grass also impacts agricultural lands as an alternate host for many of crop-damaging insects, nematodes, fungi, and viruses [128]. It hosts sorghum midges [35,69,162], southwestern corn borers [12], corn leaf aphids [106], sugarcane borers [29], banks grass mites [68], sorghum downy mildew [30], and maize viruses [96,128,161].
Little is documented on Johnson grass's impact in wildlands, and further research is needed on how Johnson grass affects wildland habitats. Generalizations about Johnson grass must always be qualified because of numerous ecotypes [125]. Typically, Johnson grass is a good competitor for nutrients [96,196], space [103], and water [166]. It can outcompete associated species for water by extracting water from lower soil profiles (12 inches (30 cm) or more below ground) [105]. Johnson grass may also negatively impact plant community composition through its reputed allelopathy [96,135,196]. Cyanogenetic glycosides and other toxins in Johnson grass may inhibit germination and growth of associated plant species [96,135,196].
On many sites in the United States, Johnson grass is not invasive in undisturbed wildlands, although it may readily invade disturbed sites (Cox, cited in [135]). Johnson grass is most invasive on moist sites in wet-temperate regions of the southeastern United States [71,72,135]. For example, Johnson grass and Canada thistle (Cirsium arvense) were listed as the 2 most invasive and expensive to control weeds on the Eastern Neck National Wildlife Refuge, Maryland [44]. Johnson grass interferes with conifer seedling establishment and growth on southern pinelands [50], and may interfere with cottonwood (Populus spp.) and willow (Salix spp.) establishment in riparian zones [171].
Johnson grass is not invasive on most sites in the Southwest. At the turn of the last century, Johnson grass was planted in southwestern arroyos and stream channels to stabilize soil [46]. It established on such wet and mesic sites, but failed to spread. Felger [61] reports Johnson grass as only weakly invasive in Organ Pipe Cactus National Monument, Arizona, where the arid climate restricts Johnson grass to roadsides and washes. Johnson grass may grow as an annual, without spreading, in arid southwestern wildlands. Nearby agricultural lands are continual seed sources [61].
Control: Although considerable information is available on controlling Johnson grass in agricultural settings (e.g., see [9,80,84,127,180]), information on controlling Johnson grass in rangelands, natural areas, and other wildlands is lacking. The following information on Johnson grass control is extracted primarily from agricultural literature but may be applied to some wildland settings, particularly old fields. Research is needed on controlling Johnson grass in wildland settings [135].
Johnson grass control involves several steps: 1) preventing seed from ripening and dispersing, 2) killing seedlings, 3) killing existing rhizomes, and 4) preventing growth of new rhizomes [9,80,84,127,180]. Control is most effective before plants have developed 5 leaves [101]. Detailed Johnson grass control procedures and techniques are given in several publications [96,127,135].
Prevention: The most efficient and effective method of managing invasive species such as Johnson grass is to prevent their invasion and spread [164]. Preventing the establishment of nonnative invasive plants in wildlands is achieved by maintaining native communities and conducting aggressive surveying, monitoring, and any needed control measures several times each year. Monitoring efforts are best concentrated on the most disturbed areas in a site, particularly along potential pathways for Johnson grass invasion: roadsides, waterways, and old fields. Large plant size makes monitoring Johnson grass relatively easy in summer, and yearly summer monitoring helps managers assess the effectiveness of control programs. As of this writing (2004), monitoring programs for Johnson grass were in their infancy. As potential contact sources, Newman [135] provides a list of managers who have started monitoring programs for Johnson grass on Natural Areas. The Center for Invasive Plant Management provides an online guide to noxious weed prevention practices.
Integrated management: A combination of complementary control methods may be helpful for rapid and effective control of Johnson grass. Integrated management includes not only killing the target plant, but establishing desirable species and discouraging nonnative, invasive species over the long term. Johnson grass control is rarely successful with only 1 method of control [141], but a combination of control methods can be effective. For example, in a tallgrass restoration study on the Hear Wildlife Sanctuary, Texas, a combination of early fall glyphosate spraying followed by late fall tillage helped control nonnative grasses on a former Johnson grass-Bermuda grass (Cynodon dactylon) pasture. Early fall spraying targeted Johnson grass while it was still actively growing. After spraying, rhizomes brought to the soil surface by tilling 4 to 6 inches (10-15 cm) deep were killed by winter frost. Johnson grass showed 4.2% cover and 50% frequency 3 years after treatments. Only trace amounts of Bermuda grass were present [172].
Fire: See Fire Management Considerations.
Biological: Biological control of Johnson grass is problematic, as known control agents that kill Johnson grass also kill crop grasses such as corn and sorghum [128,143,145]. As of this writing (2004), there are no biocontrol agents approved for Johnson grass [183]. Several biological agents are being tested for possible use. A smut (Sphacelotheca holci) has helped control Johnson grass in Louisiana croplands [130]. In Florida field trials, a mixture of native fungal pathogens controlled Johnson grass and other weedy grasses in citrus (Citrus spp.) groves [43].
Heavy grazing over 2 or more years reduces Johnson grass by depleting rhizome reserves [3,8,89]. Rhizome development is greatly reduced when plant height is kept below 12 to 15 inches (30.5-38 cm) [127]. Best control is offered when herbicide or winter plowing treatments follow grazing treatments [3]. For example, in an unpublished study at the Patagonia/Sonoita Creek Preserve, Arizona, cow and horse summer grazing reduced density of Johnson grass. After 4 years of summer grazing, Johnson grass stem density had decreased 75% compared to pretreatment levels. Plots were then sprayed in late spring with glyphosate. Posttreatment restoration plantings gave mixed results. One to two months after spraying, native bunchgrasses were transplanted onto the study sites. Broadleaf weeds invaded the study plots after Johnson grass density was reduced by the grazing and herbicide treatments. After mowing treatments to control the broadleaved weeds, native bunchgrasses on some test plots were showing good growth. Other plots experienced Johnson grass reinvasion and pocket gopher herbivory, to the detriment of native bunchgrasses. Preserve managers are continuing weed control treatments to promote the native bunchgrasses [183].
Geese are sometimes used for Johnson grass control in croplands. Geese prefer young shoots, and do not graze Johnson grass over about 7 inches (18 cm) in height [9,86].
Chemical: Herbicides may provide initial control of a new invasion or a severe infestation, but used alone, they are rarely a complete or long-term solution to invasive species management [40]. Herbicides are most effective on large infestations when incorporated into long-term management plans that include replacement of weeds with desirable species, careful land use management, and prevention of new infestations. Control with herbicides is temporary, as it does not change the conditions that allowed the invasion to occur in the first place (e.g., [211]). See The Nature Conservancy's Weed Control Methods Handbook for considerations on the use of herbicides in Natural Areas and detailed information on specific chemicals.
The most effective chemical control of Johnson grass involves using systematic herbicides that translocate the active chemicals to rhizomes [127]. A single application of herbicide generally does not control large infestations, and follow-up measures are needed for long-term control [169]. Johnson grass control can be obtained using glyphosate [7,21,104,127], phenoxy (e.g., 2,4-D, fluazifop), [108,115], or halogenated aliphatic (e.g., dalapon) herbicides [8,86,127]. Spot spraying with sodium chlorate [82,86] or dalapon has been effective for small infestations [153]. Spot control is not effective in the long term unless surrounding seed sources are also eliminated [104]. Experiments in agricultural fields in Argentina showed best control when the herbicide (dalapon) was applied when rhizome biomass was low. Ghersa and others [67] provide a model for predicting optimal spraying time based on minimum rhizome biomass. Although based on South American seasons, the model is easily adjustable for use in the northern hemisphere.
Postemergent herbicides are the most common method of Johnson grass control in agricultural systems, and are probably the best herbicide choice for wildland settings as well, since postemergent herbicides cause less damage to nontarget species. In a Maryland old-field study, foliar application of postemergence herbicide (DPX-V9360) was more effective in late-growth stages (>5 leaves) than early-growth stages (<5 leaves) when rhizomes had not fully expanded [138]. Rosales-Robles and others [158] discuss the relative effectiveness of several postemergent herbicides as influenced by application rate and Johnson grass growth stage. Application procedures for postemergent herbicides effective on Johnson grass are given in these publications: [20,51,119,208].
Ecotypes may show differential response to herbicides [128]. Populations in Kentucky and Mississippi show genetic resistance to fluazifop and other phenoxy herbicides [15,137,168]. Virginia populations have resistance to enzyme acetyl-coenzyme A carboxylase inhibitors [33]. In Greece, some populations show resistance to glyphosate [113].
Herbicide treatments greatly decreased Johnson grass cover in an Illinois bottomland old field. Restoration treatments included tillage, pre- or postemergent herbicide applications (sulfometuron or glyphosate, respectively), and green ash (Fraxinus pennsylvanica) plantings. Tillage had no significant impact on Johnson grass cover. Mean Johnson grass cover (%) was significantly lower after the 1st postspray year [76]:
Treatment Year 1 Year 2 Year 3 No herbicide 27.4 by* 0.5 ax 0.01 ax sulfometuron 1.2 ay 1.3 ay 0.01 ay glyphosate 7.3 ay 2.4 ay 0.01 ay *Columns followed by the same letter (a or b) are not significantly different. Rows followed by the same letter (x-z) are not significantly (P=0.05) different.Cultural: Little information is available on cultural methods of control for Johnson grass. An Arizona study using integrated pest management, including native bunchgrass plantings, showed some success in controlling Johnson grass (see grazing in the Biological control section above). Additional studies incorporating cultural control of Johnson grass are needed.
Physical/mechanical: Johnson grass can be controlled by tilling, mowing, and flooding [6,127,169]. Individual small plants or small clumps may be controlled by hand-pulling or solarization [13,54,169].
A consistent tillage program may provide effective control [6,42,80,125]. Tilling is not practical on most wildlands due to damage to desirable native plant species, uneven terrain, erosion, and cost constraints [104]. Tilling can be used on some sites such as bottomlands and old fields. Shallow plowing helps control Johnson grass by breaking up rhizome systems, exposing rhizomes to the sun or killing frosts, and depleting carbohydrate reserves [6,42,80,125]. Optimal plow depth is 8 to 12 inches (20-30 cm). Several treatments are needed in hot climates [86,101]. Killing sprouts early, before they form 5 leaves and start developing new rhizomes, gives best control [101]. First plowing is in spring (May), followed by similar plowings every 3 weeks (in rainy weather) to 6 weeks (in dry weather). Plant heights of 12 or more inches (30 cm) are recommended before plowing again [9]. In cold climates, Johnson grass is plowed in late October to expose rhizomes to frost [19]. An exposure of 24 or more hours to temperatures below 25 °F (- 4 °C) kills rhizomes [80,102,125,126]. A single plowing, or long intervals between plowings (>4 years), is generally not effective because it stimulates growth [104,170], buries and protects rhizomes [42], and exposes deeply buried seeds to upper soil levels where they may germinate [64].
Because rhizomes may extend more than 20 inches (51 cm) below ground, cultivation alone may fail to kill Johnson grass rhizomes [42]. After plowing, close grazing or mowing (so that the grass stays <12-15 inches (30-38 cm) tall) helps further reduce Johnson grass cover [86].
Even on old fields, tilling is a major soil disturbance that provides a favorable seedbed for pioneer species. Unless further rehabilitation efforts that include planting native herbaceous species are taken, it is likely that tilled fields will succeed to other invasive nonnatives.
Repeated, close mowing has the same inhibitory effect on growth as grazing [104,169]. In Mississippi, mowing seedlings 13 days after emergence killed them [125]. In an Alabama field experiment, multiple cuttings, starting when plants were 1 foot (0.3 m) high, slowed Johnson grass rhizome development. At the end of the growing season, plots cut 8 times averaged 15 dry-weight ounces (431 g) of Johnson grass top-growth and 0.3 dry-weight ounces (10 g) of rhizomes. Plants cut only twice had 67 ounces (1,909 g) top-growth and 26 ounces (739 g) of rhizomes. Plots were 4 à 5 feet²[179].
Flooding for 3 to 6 weeks in early spring, before rhizomes sprout, can effectively control Johnson grass. Replacing open irrigation ditches with culverts or pipes helps prevent reinfestation [127].
Hand-pulling Johnson grass usually leaves rhizome pieces behind in the soil, stimulating sprouting. It is not an effective control method unless all rhizomes are removed or new sprouts are controlled [104,169]. Best results are obtained in early spring when soil in moist and rhizomes are least likely to break [169].
Repeated solarization treatments (using a clear polyethylene tarp to trap solar heat in the soil) can control small Johnson grass infestations [13].
Seeds: Solarization of moist soil at 140 °F to 150 °F (60-70 °C) for 7 days kills most Johnson grass seeds. Solarization of dry soil does not kill Johnson grass seed [54]. In Davis, California, soil watered and solarized for 9-12 weeks supported no Johnson grass. Untreated control plots showed 58% Johnson grass cover [55]. For established plants, 30 days of solarization kills most Johnson grass. Remaining plants have grown rhizomes through and above the landscape fabric, but rhizomes above the landscape fabric were easily removed by hand-pulling [121].
Composting Johnson grass seeds in cow manure for 3 days killed the seeds. Temperatures in the compost reached 120 °F (49 °C) [203]. Ensiling for 21 days also killed Johnson grass seed [212].Although Johnson grass can be an undesirable species, it can also provide good forage for wildlife and livestock under most growing conditions [31,47,87,91].
Palatability/nutritional value: Johnson grass is moderately palatable and nutritious [47,49]. Deer make light to moderate use of Johnson grass [114,163], grazing all aboveground portions of the plant [47]. Rodents also graze Johnson grass. In honey mesquite (Prosopis glandulosa var. glandulosa) plains of Texas, Heerman's kangaroo rat and Great Basin pocket mouse used Johnson grass frequently (6.7% volume, 61% frequency; and 5.9% volume, 36% frequency, respectively) [2]. Quail, geese, and wild turkey consume Johnson grass seeds [31,47].
Although intolerant of heavy grazing, Johnson grass is a good pasture grass and makes fair-quality hay when cut in the boot stage [170,191]. Livestock make moderate to good use of fresh Johnson grass [87,91]. In a comparison of Texas range grasses, Johnson grass showed greatest in-vitro digestibility (45%-69%, depending on the digestion media) of 5 grasses tested [116]. Dairy cattle in Alabama showed good weight gain and milk production on Johnson grass pasture [87].
Nutritional content: In a western Texas study, Johnson grass had highest summer crude protein content (13.2%) of 9 rangeland grasses. Spring, fall, and winter crude protein values were 6.62%, 8.06%, and 3.81%, respectively [37]. In a greenhouse study comparing relative mineral content of 15 grass species, Johnson grass scored significantly higher in phosphorus content than other grass species (P=0.1). Cobalt, manganese, and copper contents were moderate compared to other grasses [29]. Energy value of Johnson grass grown in Texas was 3,900 kcal/g [136]; in India, seasonal fluctuation in energy value varied from 3,684 kcal/g in October to 4,578 kcal/g in April [167]. Nutritional content of fresh Johnson grass in eastern Texas was [62]:
Growth stage No. samples Protein (%) Ether extract (%) Crude fiber (%) N-free extract (%) young 6 9.22 2.28 28.51 42.35 bloom 3 5.43 1.87 30.00 43.19 mature 2 5.36 1.40 32.36 44.01Seasonal changes in forage quality of Johnson grass on the Edwards Plateau of Texas were [103]:
Plant part Date Water (%) Ash (%) Cell wall (%) P (%) Protein (%) Digestible organic matter (%) leaves 5/24/73 71 10 55 0.38 15 73 leaves and stems 6/28/73 68 9 60 0.21 12 70 leaves 10/25/73 76 9 66 0.16 10 63When harvested at its peak, Johnson grass makes fair-quality hay, similar to timothy (Phleum pratense) hay in nutrient content [146]. In a 1928 study in an Alabama coal mine, draft horses and mules were fed oat (Avena sativa) grain and either Johnson grass or timothy hay for 3 months. The equines maintained their weight on both diets under "moderate" workloads. The animals lost weight on both diets under "heavy" workloads, but lost less weight on timothy hay and grain compared to Johnson grass hay and grain (mean losses of 10.71 and 21.78 lbs., respectively). Digestible nutrient means were [75]:
Total dry matter per 100 lbs.
Digestible nutrients per 100 lbs.
Crude protein Carbohydrates Fat Total Johnson grass hay 89.9 2.9 45.0 1.0 50.1 timothy hay 88.4 3.0 42.8 1.2 48.5Toxicity: Johnson grass is generally a good forage grass [31,47,87,91]. However, at certain developmental stages or under some adverse environmental conditions, Johnson grass may form cyanogenetic glycosides that can poison livestock. Phenologically, Johnson grass is most toxic when leaves and culms are actively growing. Seedlings and sprouts generally have higher levels of glycosides than plants that have reached the flowering stage. Secondary growth, produced after mature plants are mowed or heavily grazed, can also have high levels of glycosides. Environmentally, Johnson grass is most toxic after drought, extreme heat, frost, or when plants are wet with dew or light rain. Glycoside levels can vary considerably among Johnson grass populations. Ruminants, especially cattle, are more susceptible to glycoside poisoning than monogastric herbivores like horses [157,173]. As well as fresh plants, hay cut when Johnson grass is young or experiencing adverse environmental conditions such as drought can also be toxic [81,133,170,170]. Livestock poisoning can be prevented by waiting until new growth is 15 to 18 inches tall (38-46 cm) tall after drought, or deferring grazing until plants have dried after frost [128].
Johnson grass may sequester selenium or other elements that are toxic at high doses when growing in soils with high concentrations of toxic elements. In the Dead Sea area of Jordan, for example, selenium concentrations in Johnson grass samples were high enough to poison livestock [1].
Prolonged consumption of fresh Johnson grass can cause nitrate poisoning in ungulates [173]. Most livestock can graze Johnson grass safely when plants are at least 18 inches (46 cm) tall [170].
Cover value: No information is available on this topic.
Fire may promote Johnson grass growth. Spring prescribed burning increased Johnson grass biomass in a short-term study in Georgia. Old fields were burned on 5 March, 1970. In the 1970 postfire growing season (March-October), Johnson grass net productivity averaged 27.42 g/m² on burned plots and 0.20 g/m² on unburned control plots. Prescribed burning significantly reduced the litter layer during the first 5 postfire months, and plants on burned plots showed increased spring nitrogen uptake compared to control plots (P=0.05) [140]. Reduced litter and increased nitrogen uptake probably enhanced Johnson grass growth on burned plots.
Published information on postfire seedling establishment of Johnson grass is lacking. Studies are needed on the ability of Johnson grass to establish from seed in postfire environments.
Johnson grass reproduces from rhizomes and from seed [42,86,96].
Asexual regeneration: Once a population of Johnson grass is established, most population growth is from asexual regeneration by rhizomes [96]. Throughout most of their North American range, Johnson grass populations are strongly rhizomatous [49,71,122,184,201]. Some Johnson grass populations are weakly rhizomatous or nonrhizomatous, especially at the species' distributional limits [61,197,198]. Rhizome expression in Johnson grass is apparently controlled by multiple, dominant genes, resulting in variable degrees of rhizome development in both Johnson grass and its hybrids [209]. Extreme temperatures also inhibit Johnson grass's ability to produce rhizomes [85,175].
Rhizome development: Johnson grass plants begin growing rhizomes in the seedling stage. Primary rhizomes are initiated at the 5-leaf stage, when plants are about a foot tall. Rhizome growth continues slowly until the 10-leaf stage, then accelerates greatly. Rhizomes are well developed by 6 to 7 weeks [6,101,125]. In a greenhouse experiment, Anderson and others [6] noted extensive rhizome development on 4.5-month-old plants, with over 5,200 rhizome nodes/plant.
In older plants, last-year or primary rhizomes produce new, secondary rhizomes in spring. Secondary rhizomes in turn produce tertiary rhizomes. Secondary and tertiary rhizome growth slows or stops during flowering, then resumes with seedhead development [126]. Rhizome production peaks at seed ripening [78,97], when a single plant may produce 200 to 300 feet (60-90 m) of rhizomes [127]. Secondary and tertiary rhizomes continue growth and carbohydrate accumulation until late fall, then go dormant over winter. Primary rhizomes die each fall. In spring, secondary and tertiary rhizomes become current-year primary rhizomes [4,42,80,86,96,101].
Rhizome sprouting: Small or broken rhizomes, especially secondary rhizomes, can form new plants [6,9,42,173]. Plows spread Johnson grass by breaking up, dispersing, and replanting rhizomes [3] (see Physical/mechanical control). Small rhizomes are more likely to sprout when shallowly buried, while large rhizomes are more likely to sprout when deeply buried. In the greenhouse, 3-inch (7.6-cm) rhizome sections sprouted best when planted less than 3 inches deep. Longer, 6-inch (15.2-cm) sections sprouted best when buried deeper than 3 inches ([39] and references therein). In a Mississippi field experiment, McWhorter [125,126] found that with shallow burial (<2 inches (6 cm)), short rhizomes (<3 inches (7.6 cm)) produced more sprouts than long rhizomes (6 inches (15.2 cm)). The opposite trend occurred when rhizomes were planted deeper than 2.4 inches (6 cm). Rhizomes usually grow to a depth of 10 to 20 inches (25-50 cm) [127]. Loose, sandy or loamy soils generally allow for best rhizome expansion [126]. Clay tends to inhibit rhizome expansion [86]; however, rhizomes may penetrate several feet down cracks in clay soil [126]. Deeply buried rhizomes that do not sprout do not survive more than a year [4,80,96].
Rhizomes are somewhat drought-resistant, remaining viable after drying to 40% of initial harvest weight [6]. They are sensitive to extreme temperatures. In northern climates, rhizomes must be deeply buried in order to overwinter. In an Illinois field experiment, Johnson grass rhizomes did not survive winter temperatures less than 1.4 °F (-17 °C) unless buried 7.9 inches (20 cm) or more below ground [175]. In southern Ontario, rhizomes must be 10 inches (25 cm) or more inches below ground to overwinter ([85] and references therein).
Sexual regeneration: Although growth of established populations is primarily through rhizomes, Johnson grass establishes new populations through seed spread [96].
Breeding system: Sorghum species are mostly self-crossed, although some outcrossing occurs ([196] and references therein).
Pollination: Johnson grass is primarily self-pollinated [196]. Some pollination is effected by wind, especially when plants are <425 feet (130 m) apart [196,202].
Seed production: Johnson grass is a short-day plant, requiring 8 to 16 hours of daylight to flower [66,135]. It is a good seed producer under favorable growing conditions. A single plant may produce 80,000 or more seeds in 1 growing season [3,84]. Two seed crops may be produced under good conditions. In agricultural fields in Argentina, Johnson grass produced a large seed crop in early summer (Jan-Feb.; 60% of total seed production for the year) and a smaller seed crop in late summer-early fall (mid-March-early April; 40% of annual seed production) [66]. Johnson grass seed production is estimated at 90 gallons/acre (855 l/ha) on good sites in the South. Field trials in Mississippi showed mean seed production of 84 g/plant and 28,000 seeds/plant [127,196]. Resources are allocated to rhizomes at the expense of seeds under poor growing conditions [22,23].
Greenhouse trials using Johnson grass seed from the Northeast showed populations that grow and reproduce as annuals have faster growth rates, more rapid development, more and larger seeds, and fewer rhizomes compared to populations that sprout from overwintered rhizomes [198].
Seed dispersal: Wind, water, machinery, and animals disperse Johnson grass seeds [3,65,84,85,182]. Spikelets are readily deciduous [201] and usually disperse as a unit beneath the parent plant [3,65,70,72]. Strong winds disperse seeds longer distances. In Argentina, 28- to 31-mile/hr (45- to 50-km/hr) winds that occurred during May thunderstorms carried Johnson grass seeds 2,950 to 3,300 feet (900-1,000 m) from parent plants [65]. Water has dispersed seeds along many waterways of the United States [3,84,182]. Farming equipment also spreads seeds [65,84]. Viable Johnson grass seed is a common contaminant in hay, harvested crops, and commercial seed [3,142]. Johnson grass seed retains viability after passing through the digestive tracts of livestock [9,84,126]. The relative importance of agents that disperse Johnson grass seed is unclear [128].
Seed banking: Johnson grass builds up a soil seed bank [189]. The seeds are dormant and may remain viable for several years, although most soil-stored seeds germinate in their 1st or 2nd year [3,96,135]. In Mississippi, 1st-year stratified seed showed 82% viability in the field. After burial in the field for 2.5 years, the same seed lot showed 62% viability [53]. In California, 5-year-old buried seed showed >50% viability, but viability dropped to 2% by age 6 [120].
Germination: Johnson grass has 2 mechanisms of dormancy: mechanical dormancy imposed by the seed hull and seedcoat, which requires weathering or scarification to break; and chemical dormancy, which requires oxygen to break [100]. Diurnal fluctuations in temperature, afterripening, or both are needed to overcome both types of dormancy [26,26,64,99,181]. Seed from water-stressed plants is generally less dormant than seed from amply watered plants [23]. Benech and others [25] present a model predicting loss of seed dormancy and consequent seedling emergence based on soil temperature.
Light improves germination rate with warm temperatures (>93 °F (34 °C)) and inhibits germination with cold temperatures (<72 °F (22 °C) [100]. In the greenhouse, Taylorson and McWhorter [181] found a 63% increase in germination rate for Johnson grass seed exposed to light vs. seeds kept in the dark. Deeply buried seed remains dormant for at least 7 years [84] but does not germinate [27,64,99]. Soil upheaval such as cultivation, which brings seed closer to the soil surface, usually increases germination rates [64,99]. In the greenhouse, best germination (60-75%) occurred with surface-scattered to shallowly buried (0-1.6 inches (0-4 cm)) seed. Less than 5% germination occurred with seed buried >3 inches (8 cm) below the soil surface [27]. Litter cover or shallow burial may aid germination in the field. Prostko and others [147] present a model to predict Johnson grass seedling emergence based upon temperature and seed burial depth.
Seedling establishment/growth: Best establishment occurs on open, disturbed sites. Seed dispersed away from parent plants may show better establishment compared to seed falling beneath the parent. In an old field in Argentina, most Johnson grass seed fell near parent plants on undisturbed plots. Only 1% of seed beneath a parent plant established. On tilled plots mowed every 1 to 2 weeks by a corn (Zea mays) harvester, seed was carried 3 to 82 feet (1-25 m) from parent plants. Recruitment of tilled seed neared 100% [65]. On favorable sites, plants may produce 80 or more culms in their 1st year [3].
In areas where Johnson grass grows as a facultative annual, it shows variable ability to regenerate from seed. Johnson grass annuals in rural-interface wildlands of southern Arizona rarely reproduce either from on-site seed or from rhizomes. Seed dispersed from adjacent agricultural lands provide continual sources of seed [61]. However, some annual populations in the northern portion of Johnson grass's range successfully reproduce from seed. In southern Ontario, northern Ohio, and northern New York, annual populations have larger leaves, inflorescences, and seeds compared to perennial Johnson grass populations [198].
Johnson grass seedlings may show faster 1st-year growth than plants started from rhizome fragments. On the Mississippi Delta near Stoneville, Mississippi, Johnson grass started from seed showed greater biomass and more rapid height gain than plants started from rhizome pieces. At flowering, seed plants were producing 0.75 to 3 feet (0.23-0.9 m) of new rhizome growth per day. Plant growth patterns were as follows (data are means) [125]:
Biomass and height of Johnson grass seedlings
Date (1959)
Days after emergence
Green weight (g)
Height (in)Rhizome length (ft)
Leaves Rhizomes Roots Seedhead May 20 20 12 2 3 ----* 12 ---- May 27 27 190 30 30 ---- 23 <1 June 15 46 690 90 100 ---- 52 7 July 1 62 1990 750 220 180 74 35 Sept. 1 124 2950 5050 360 500 74 153 Sept. 29 152 3140 8070 430 680 74 212Biomass and height of Johnson grass rhizome sprouts
May 20 19 9 3 3 ---- 9 ---- May 27 26 80 14 20 ---- 13 <1 June 3 33 530 100 40 ---- 30 1 June 15 45 610 110 130 ---- 47 5 June 19 49 590 310 160 9 70 9 June 24 54 950 220 160 74 72 14 *Not present.Johnson grass is a pioneer species, and is often found on old fields [71], frequently inundated, or otherwise disturbed sites [71,83,169]. Johnson grass is not restricted to disturbed sites, however; it also invades undisturbed tallgrass and coastal prairies, savannas, and riparian zones [45,169]. In an Oklahoma study of succession in little bluestem (Schizachyrium scoparium) prairie, Johnson grass was most common in midsuccessional seres, when other weeds and woody species were succeeding to tallgrass prairie species [45]. Johnson grass's spread through rhizomes may slow succession, especially in grassland ecosystems [169].
Old fields: Johnson grass is particularly common on old bottomland fields in the South [3,17,18]. Unlike most crop weeds, which tend to decrease in the absence of irrigation and fertilization, Johnson grass tends to persist on abandoned fields. For example, in Georgia it was prevalent in 1-, 4-, and 8-year-old fertilized crop fields, but was also prevalent in 8-year-old fallow fields [139].
Shade tolerance: Johnson grass requires open sites and does not persist under closed canopies [77,190]. In a honey mesquite (Prosopis glandulosa) Texas savanna, Johnson grass associated with Texas wintergrass (Nassella lecotricha) in open areas but was not found under honey mesquite or other trees [190]. In Argentina grasslands, canopy removal increased Johnson grass germination and establishment compared to closed-canopy sites [25].
El sorgo d'Alep (en llatí Sorghum halepense) (usualment dit canyota, milloca, panissola, encara que aquests noms també s’apliquen a altres plantes), és una espècie de planta herbàcia perenne del gènere del sorgo considerada una mala herba molt important. Té un rizoma i fa llargues inflorescències en panícula de fins a 30 o 40 cm. Les fulles són llargues i amb una nervació central blanca evident Creix en herbassars, com planta ruderal i afecta principalment als conreus de regadiu els de dacsa i l’alfals.[1]
És una espècie nativa de la conca del mediterrani però actualment creix a tota Europa, Orient Mitjà i a altres parts del món.
Es multiplica tant per via sexual (per llavors) o vegetativa (pels rizomes).
La canyota s’ha utilitzat com planta farratgera i per aturar l’erosió però principalment és una mala herba nociva, considerada entre les 1o ptijors del món. per les següents raons::
El sorgo d'Alep (en llatí Sorghum halepense) (usualment dit canyota, milloca, panissola, encara que aquests noms també s’apliquen a altres plantes), és una espècie de planta herbàcia perenne del gènere del sorgo considerada una mala herba molt important. Té un rizoma i fa llargues inflorescències en panícula de fins a 30 o 40 cm. Les fulles són llargues i amb una nervació central blanca evident Creix en herbassars, com planta ruderal i afecta principalment als conreus de regadiu els de dacsa i l’alfals.
És una espècie nativa de la conca del mediterrani però actualment creix a tota Europa, Orient Mitjà i a altres parts del món.
Planhigyn blodeuol Monocotaidd a math o wair yw Sorgwm porthiant sy'n enw gwrywaidd. Mae'n perthyn i'r teulu Poaceae. Yr enw gwyddonol (Lladin) yw Sorghum halepense a'r enw Saesneg yw Johnson grass.[1]
Gall dyfu bron mewn unrhyw fan gan gynnwys gwlyptiroedd, coedwigoedd a thwndra. Dofwyd ac addaswyd y planhigyn gan ffermwyr dros y milenia; chwiorydd i'r planhigyn hwn yw: india corn, gwenith, barlys, reis ac ŷd.
Planhigyn blodeuol Monocotaidd a math o wair yw Sorgwm porthiant sy'n enw gwrywaidd. Mae'n perthyn i'r teulu Poaceae. Yr enw gwyddonol (Lladin) yw Sorghum halepense a'r enw Saesneg yw Johnson grass.
Gall dyfu bron mewn unrhyw fan gan gynnwys gwlyptiroedd, coedwigoedd a thwndra. Dofwyd ac addaswyd y planhigyn gan ffermwyr dros y milenia; chwiorydd i'r planhigyn hwn yw: india corn, gwenith, barlys, reis ac ŷd.
Sorghum halepense ist eine Pflanzenart aus der Gattung der Sorghumhirsen (Sorghum) innerhalb der Familie der Süßgräser (Poaceae). Sie ist fast weltweit verbreitet. Sie wird als „Ackerunkraut“ bewertet in landwirtschaftlichen Kulturen subtropischer bis tropischer Breiten, sie gilt aufgrund von Herbizidresistenz als Problemunkraut mit teilweise hohen Schäden. Sie kommt in Mitteleuropa, besonders im Süden, adventiv, mit Tendenz zur Einbürgerung, vor. Deutschsprachige Trivialnamen sind gelegentlich Wilde Sorghumhirse,[1] Aleppo-Mohrenhirse,[2] Wilde Mohrenhirse, Aleppohirse[3] oder (wie in Englischer Sprache) Johnsongras[4].
Sorghum halepense ist eine ausdauernde krautige Pflanze. Sie bildet relativ lange, unterirdisch kriechende Rhizome. Die oberirdischen Pflanzenteile sterben im Winter ab, das Rhizom überwintert. Dieses robuste, aufrechte Süßgras erreicht in Mitteleuropa Wuchshöhen von 140[3] bis 150[2][5] Zentimetern, in wärmeren Klimaten manchmal sogar 200 Zentimetern[6]. Der Halm ist rund, kahl, nur an den Knoten dicht hell flaumig behaart (selten kahl) und gelegentlich an der Basis verzweigt.
Jungpflanzen von Sorghum halepense können auf dem Acker leicht mit etwas schmalblättrigen Exemplaren von Mais (Zea mays) verwechselt werden. Von den Kulturpflanzen Sorghumhirse und Sudangras ist eine habituelle Unterscheidung bei jungen Pflanzen anhand der Rhizome und der viel kleineren Ährchen möglich.[7]
Die wechselständig angeordneten Laubblätter sind in Blattscheide und Blattspreite gegliedert. Die Blattscheide ist kahl. Das Blatthäutchen ist 1[5] bis 2,[2] oder sogar 6[6] Millimeter lang, gestutzt und am Rand bewimpert oder mit Hautsaum. Die einfache, glatte und kahle Blattspreite ist 80[5] bis 90[6] Zentimeter lang und 1 bis 2 oder bis zu 4[6] Zentimeter breit.
Der lockere, ausgebreitete rispige Blütenstand ist in Europa bis zu 30 Zentimeter lang,[2][8] in Nordamerika bis zu 50 Zentimeter[6] lang. Die Ährchen sind, wie typisch für die Gattung Sorghum, ungleich, jeweils ein zwittriges und ein rein männliches (oder gelegentlich steriles) Ährchen sitzen paarweise zu zweit bis fünft in einem traubenartigen Teilblütenstand. Das zwittrige Ährchen ist sitzend, abgeflacht und mit einer Länge von selten 3,8 bis, meist 5 bis 6 Millimetern elliptischem Umriss. Es sind zwei harte, ledrige, behaarte, gelbe Hüllspelzen vorhanden. Ihre häutige, zweispitzige Deckspelze trägt oft, aber nicht immer, eine gekniete Granne (die unbegrannte Form wurde als Sorghum halepense var. muticus beschrieben, dies wird von den meisten Autoren nicht mehr anerkannt). Es ist meist keine Vorspelze vorhanden. Das männliche Ährchen ist lang gestielt, ist 4,5 bis 6, selten bis zu 7 Millimeter lang, es ist oft purpurn überlaufen. Ihre Spelzen sind stets unbegrannt.
Der Fruchtstand zerfällt zur Fruchtreife, jeweils unterhalb der ungestielten Ährchen und verstreut so die Körner (Karyopsen), daran ist diese Art leicht von der Kulturpflanze Sorghumhirse (Sorghum bicolor) zu unterscheiden, bei der die Ährchen, wie typisch für Getreide, bis zum Drusch auf der Pflanze verbleiben.
Sorghum halepense wächst überwiegend als „Unkraut“ im Kulturland, insbesondere auf Getreideäckern. In der Auflistung von Leroy G. Holm: The World's Worst Weeds gehört es zu den zehn ökonomisch bedeutendsten Unkräutern weltweit,[9] mit Schwerpunkt in Kulturen von Mais, Baumwolle und Zuckerrohr. Sorghum halepense kommt weltweit in tropischen und subtropischen Breiten vor und strahlt von hier aus in die warmgemäßigten Zonen aus. Als ursprüngliche Heimat gilt das südliche Eurasien, vom östlichen Mittelmeerraum bis Indien.[10]
In Nordamerika werden Ertragsverluste von 25-50 Prozent bei Zuckerrohr, 12-33 Prozent im Mais und 23-42 Prozent in Sojabohnen angegeben.[7] Sorghum halepense bildet fruchtbare (fertile) Hybride mit der Getreideart Sorghumhirse aus, was deren Zucht durch genetische Introgression behindert. Andererseits ist Sorghum halepense ein ertragreiches und beliebtes Weidegras und Viehfutter. Ein Anbau, etwa auch zur Biomassegewinnung, wird wegen der ökonomischen Probleme als Unkraut nicht mehr so oft wie früher durchgeführt. Früher wurde die Art als Viehfutter ausgesät und so künstlich verbreitet.[7] In Afrika, so in Simbabwe wird sie als Viehfutter angebaut, sie verwildert hier an feuchten Standorten wie Flussufern.[11]
Nach Norden wird die Verbreitung durch die Frostempfindlichkeit der Rhizome begrenzt. Im Experiment überlebten diese Temperaturen unter -3 °C weniger als 24 Stunden lang. In Nordamerika überlebten Rhizome in mehr als 20 Zentimeter Bodentiefe aber Lufttemperaturen von -9 °C über längere Zeiträume.[7] Während die oberirdischen Pflanzenteile empfindlich gegenüber sehr hohen Lufttemperaturen und Dürre sind, können die Rhizome sowohl Dürrezeiten wie mehrere Wochen Überflutung ertragen. Sorghum halepense gedeiht am besten auf gut wasserversorgten, nährstoffreichen, lockeren, neutralen bis schwach sauren Böden.
In Nordamerika wurde die hier Johnsongras genannte Art um 1800 als Viehfutter eingeführt. Sie ist, neben dem Vorkommen in Äckern und Kulturland, weit verbreitet verwildert auf Weiden, in Unkrautfluren und an Ufern, immer auf gut wasserversorgten Standorten, wobei der Oberboden trocken sein kann, wenn in der Tiefe Wasser vorhanden ist. Sorghum halepense etabliert sich nur auf oft gestörten Böden und wird aus dichter, ungestörter Vegetation verdrängt. Versuche einer Bekämpfung überdauert es aber lange Zeit aufgrund der unterirdischen Rhizome. Sorghum halepense wird oft vom Weidevieh ausgebreitet, da die harten Samen die Darmpassage unbeschadet überstehen. In gemähten Beständen vermag es sich nicht zu halten.[12]
Die Erstveröffentlichung erfolgte 1753 unter dem Namen (Basionym) Holcus halepensis durch Carl von Linné in seinem Werk Species Plantarum, Tomus II, S. 1047. Die Neukombination zu Sorghum halepense wurde 1805 durch Christian Hendrik Persoon in Syn. pl. 1, S. 101 veröffentlicht.
Sorghum halepense wird mit der Sorghumhirse Sorghum bicolor sowie der ebenfalls rhizombildenden Sorghum propinquum zur Sektion Sorghum in der Untergattung Sorghum s. str. innerhalb der Gattung SorghumhirsenSorghum gestellt.[10] Im Gegensatz zu den meisten anderen Arten der Gattung Sorghum ist Sorghum halepense tetraploid mit einer Chromosomenzahl von 2n = 2x = 40. Deshalb wurde schon seit längerer Zeit vermutet, dass Sorghum halepense auf eine Hybridisierung zweier anderer Sorghum-Arten zurückgeht. Die vermuteten Eltern sind Sorghum bicolor und Sorghum propinquum. Eine ebenfalls diskutierte Beteiligung von Sorghum virgatum ist nach genetischen Untersuchungen unwahrscheinlich.[13]
Sorghum halepense ist eine Pflanzenart aus der Gattung der Sorghumhirsen (Sorghum) innerhalb der Familie der Süßgräser (Poaceae). Sie ist fast weltweit verbreitet. Sie wird als „Ackerunkraut“ bewertet in landwirtschaftlichen Kulturen subtropischer bis tropischer Breiten, sie gilt aufgrund von Herbizidresistenz als Problemunkraut mit teilweise hohen Schäden. Sie kommt in Mitteleuropa, besonders im Süden, adventiv, mit Tendenz zur Einbürgerung, vor. Deutschsprachige Trivialnamen sind gelegentlich Wilde Sorghumhirse, Aleppo-Mohrenhirse, Wilde Mohrenhirse, Aleppohirse oder (wie in Englischer Sprache) Johnsongras.
கருப்பன் புல் (ஆங்கில பெயர் : Johnson grass) என்ற இந்த புல் வகையைச் சார்ந்த போஅசி (Poaceae) என்ற குடும்பத்தைச் சார்ந்த நடுநில கடல் பகுதிகளை பூர்வீகமாகக் கொண்ட தாவரம் ஆகும். மேலும் ஐரோப்பா , மத்திய கிழக்கு நாடுகள் போன்ற இடங்களிலும் அதிகமாக காணப்படுகிறது. அது கிழங்குகள் மற்றும் விதைகள் மூலம் இனப்பெருக்கம் செய்கிறது. இத்தாவரம் களைபோல் தோன்றினாலும் உடம்பில் ஏற்படும் அரிப்பைத் தடுக்கும் சக்தி கொண்டது.[1][2]
கருப்பன் புல் (ஆங்கில பெயர் : Johnson grass) என்ற இந்த புல் வகையைச் சார்ந்த போஅசி (Poaceae) என்ற குடும்பத்தைச் சார்ந்த நடுநில கடல் பகுதிகளை பூர்வீகமாகக் கொண்ட தாவரம் ஆகும். மேலும் ஐரோப்பா , மத்திய கிழக்கு நாடுகள் போன்ற இடங்களிலும் அதிகமாக காணப்படுகிறது. அது கிழங்குகள் மற்றும் விதைகள் மூலம் இனப்பெருக்கம் செய்கிறது. இத்தாவரம் களைபோல் தோன்றினாலும் உடம்பில் ஏற்படும் அரிப்பைத் தடுக்கும் சக்தி கொண்டது.
ಗಲಗು-ಸೋರ್ಗಂ ಹ್ಯಾಲಪೆನ್ಸ್ ಎಂಬ ವೈಜ್ಞಾನಿಕ ಹೆಸರಿನ ಏಕದಳ ಸಸ್ಯ. ಪೋಯೇಸೀ ಕುಟುಂಬಕ್ಕೆ ಸೇರಿದೆ.
ಯುರೋಪು ಮತ್ತು ಆಫ್ರಿಕದ ಮೆಡಿಟರೇನಿಯನ್ ಪ್ರದೇಶಗಳ ಮೂಲನಿವಾಸಿಯಾದ ಈ ಸಸ್ಯವನ್ನು ಮೊಟ್ಟಮೊದಲು ಕರ್ನಲ್ ಜಾನ್ಸನ್ ಎಂಬಾತ ತಂದು ಬೆಳೆಸಿದ್ದರಿಂದ ಇದನ್ನು ಜಾನ್ಸನ್ ಹುಲ್ಲು ಎಂದೂ ಕರೆಯುವುದುಂಟು. ದಪ್ಪವಾಗಿ ಎತ್ತರಕ್ಕೆ ಬೆಳೆಯುತ್ತದೆ. ಇದೊಂದು ಬಹುವಾರ್ಷಿಕ ಹುಲ್ಲು. ಇದಕ್ಕೆ ಅಗಲವಾದ ಎಲೆಗಳಿವೆ. ಎಲೆಯ ಮಧ್ಯನಾಳ ದಪ್ಪ ಮತ್ತು ಬಿಳುಪಾಗಿರುತ್ತದೆ. ಹೂಗಳು ಅಗಲವಾದ ಪ್ಯಾನಿಕಲ್ ಮಾದರಿಯ ಗೊಂಚಲಲ್ಲಿ ಜೋಡಣೆಗೊಂಡು ಅರಳಿದಾಗ ಎದ್ದುಕಾಣುತ್ತದೆ. ಬೀಜಗಳು ಬಲಿತಾಗ ಸಿಡಿದು ಪ್ರಸಾರವಾಗುತ್ತವೆ. ಇತರ ಹುಲ್ಲುಸಸ್ಯಗಳಲ್ಲಿರುವ ತೊಡಕು ಬೇರುಗಳ ಜೊತೆಗೆ ಇದಕ್ಕೆ ಅನೇಕ ಗುಪ್ತಕಾಂಡಗಳೂ ಇವೆ. ಗುಪ್ತಕಾಂಡಗಳ ಗೆಣ್ಣುಗಳಿಂದ ಕೊಂಬೆಗಳು ಹೊರಟು ಹೊಸಗಿಡಗಳಾಗಿ ಬೆಳೆಯುತ್ತವೆ. ಮಣ್ಣಿನಲ್ಲಿ 15-20 ಸೆಂ.ಮೀ ಕೆಳಕ್ಕೆ ಇವು ಅಡಗಿರುತ್ತವೆ. ಕಾಂಡ 7-15 ಸೆಂ.ಮೀ ಎತ್ತರಕ್ಕೆ ಬೆಳೆಯುತ್ತದೆ.
ನದಿಯ ಮೆಕ್ಕಲುಮಣ್ಣಿನ ಮತ್ತು ಎರೆಮಣ್ಣಿನ ಭೂಮಿಗಳಲ್ಲಿ ಗಲಗು ಚೆನ್ನಾಗಿ ಬೆಳೆಯುತ್ತದೆ. ಇದು ಚೆನ್ನಾಗಿ ಬೆಳೆಯಲು ಮಳೆ, ಹಳ್ಳಗಳಿಂದ ಉಕ್ಕುವ ನೀರು, ನೀರಾವರಿಯ ಪ್ರದೇಶ ಇತ್ಯಾದಿಗಳಿಂದ ಒದಗುವ ತೇವ ಆವಶ್ಯಕ. ಬಿಸಿಲನ್ನು ಬಯಸುವ ಈ ಸಸ್ಯ ಉಷ್ಣತೆ ಹೆಚ್ಚಾಗಿರುವೆಡೆ ಚೆನ್ನಾಗಿ ಬೆಳೆಯುತ್ತದೆ. ಸು.1/2 ಹೆಕ್ಟೇರಿಗೆ ಸುಮಾರು 10-12 ಕೆ.ಜಿ ಬೀಜ ಬಿತ್ತನೆಗೆ ಬೇಕಾಗುತ್ತದೆ. ಚೆನ್ನಾಗಿ ಬೆಳೆದು ಫಲ ಬಿಟ್ಟ ಮೇಲೆ ಪೈರನ್ನು ಕತ್ತರಿಸಿದ ಅನಂತರ ಮತ್ತೆ ಗಿಡ ಚಿಗುರಿ ಮರುಫಸಲು ನೀಡುತ್ತದೆ. ಹೀಗೆ ವರ್ಷಕ್ಕೆ ಎರಡು ಬೆಳೆ ಬೆಳೆಸಬಹುದು. ನೀರಾವರಿ ಭೂಮಿಯಲ್ಲಿ ಎಕರೆಗೆ 5-6 ಟನ್ ಫಸಲು ದೊರಕುತ್ತದೆ. ನದೀ ಬಯಲು ಭೂಮಿಯಲ್ಲಿ 3-4 ಟನ್ ಫಸಲನ್ನು ಪಡೆಯಬಹುದು. ಮಳೆ ನೀರನ್ನು ಆಶ್ರಯಿಸಿರುವೆಡೆ ಎಕರೆಗೆ 1-3 ಟನ್ ಫಸಲು ದೊರಕುವುದು. ತೆನೆ ಬಂದಾಗ ಅಥವಾ ಹಾಲು ಹಿಡಿದಾಗ ಕಟಾವು ಮಾಡುವುದರಿಂದ ಸಸಾರಜನಕಾದಿ ವಸ್ತು ಅತ್ಯಧಿಕ ಪ್ರಮಾಣದಲ್ಲೂ ನಾರು ಕಡಿಮೆ ಪ್ರಮಾಣದಲ್ಲೂ ಇರುತ್ತವೆ. ಮೇವಿನಲ್ಲಿ ಶೇ.3.9 ಭಸ್ಮಾಂಶ (ಆ್ಯಷ್), ಶೇ.7.8 ಸಸಾರಜನಕಾದಿ ವಸ್ತುವೂ ಶೇ.1.7 ಮೇದೋಭಾಗವೂ ಶೇ.32.0 ನಾರೂ ಇರುತ್ತವೆ.
Johnson grass or Johnsongrass, Sorghum halepense, is a plant in the grass family, Poaceae, native to Asia and northern Africa.[1] The plant has been introduced to all continents except Antarctica, and most larger islands and archipelagos. It reproduces by rhizomes and seeds.
Johnson grass has been used for forage and to stop erosion, but it is often considered a weed because:
This species occurs in crop fields, pastures, abandoned fields, rights-of-way, forest edges, and along streambanks. It thrives in open, disturbed, rich, bottom ground, particularly in cultivated fields. Johnson grass that is resistant to the common herbicide glyphosate has been found in Argentina and the United States.[2][3][4] It is considered to be one of the ten worst weeds in the world.[5] In the United States, Johnson grass is listed as either a noxious or quarantined weed in 19 states.[6] With Sorghum bicolor it is a parent of Sorghum × almum, a forage crop also considered a weed in places.[7]
It is named after an Alabama plantation owner, Colonel William Johnson, who sowed its seeds on river-bottom farm land circa 1840. The plant was already established in several US states a decade earlier, having been introduced as a prospective forage or accidentally as a seedlot contaminant.[8][9][10]
In early 20th century Talladega County (Alabama), feelings about Johnson grass were mixed. It was considered a nutritious, palatable and productive forage, but many farmers still found it undesirable. Fields of this grass fell into a "sod bound" state of insufficient new growth unless they were plowed every two or three seasons.[11]
A genetic study employing microsatellite markers has investigated Johnsongrass populations across 12 US states and confirmed that the weed was introduced to US from Alabama and North Carolina. Moreover, the study also detected an unreported independent introduction from Arizona. After trans-continental railroad building the two founding populations began to intermix at around Texas shifting diversity from centers of introduction.[12]
The 1889 book The Useful Native Plants of Australia records that Sorghum halepense is a "strong, erect-growing species, varying from two to ten feet high, succulent when young, a splendid grass for a cattle run, though not much sought after by sheep. It is a free seeder. The settlers on the banks of the Hawkesbury (New South Wales) look upon it as a recent importation, and seed of it has been distributed under the name of Panicum speciabile. (WooUs) Coast of Queensland, New South Wales, and Western Australia."[13]
.jpg)
.jpg)
.jpg)
.jpg)
{{cite book}}: CS1 maint: uses authors parameter (link) Johnson grass or Johnsongrass, Sorghum halepense, is a plant in the grass family, Poaceae, native to Asia and northern Africa. The plant has been introduced to all continents except Antarctica, and most larger islands and archipelagos. It reproduces by rhizomes and seeds.
Johnson grass has been used for forage and to stop erosion, but it is often considered a weed because:
Foliage that becomes wilted from frost or hot, dry weather can contain sufficient amounts of hydrogen cyanide to kill cattle and horses if it is eaten in quantity. The foliage can cause 'bloat' in such herbivores from the accumulation of excessive nitrates; otherwise, it is edible. It grows and spreads rapidly, it can 'choke out' other cash crops planted by farmers.This species occurs in crop fields, pastures, abandoned fields, rights-of-way, forest edges, and along streambanks. It thrives in open, disturbed, rich, bottom ground, particularly in cultivated fields. Johnson grass that is resistant to the common herbicide glyphosate has been found in Argentina and the United States. It is considered to be one of the ten worst weeds in the world. In the United States, Johnson grass is listed as either a noxious or quarantined weed in 19 states. With Sorghum bicolor it is a parent of Sorghum × almum, a forage crop also considered a weed in places.
It is named after an Alabama plantation owner, Colonel William Johnson, who sowed its seeds on river-bottom farm land circa 1840. The plant was already established in several US states a decade earlier, having been introduced as a prospective forage or accidentally as a seedlot contaminant.
In early 20th century Talladega County (Alabama), feelings about Johnson grass were mixed. It was considered a nutritious, palatable and productive forage, but many farmers still found it undesirable. Fields of this grass fell into a "sod bound" state of insufficient new growth unless they were plowed every two or three seasons.
A genetic study employing microsatellite markers has investigated Johnsongrass populations across 12 US states and confirmed that the weed was introduced to US from Alabama and North Carolina. Moreover, the study also detected an unreported independent introduction from Arizona. After trans-continental railroad building the two founding populations began to intermix at around Texas shifting diversity from centers of introduction.
The 1889 book The Useful Native Plants of Australia records that Sorghum halepense is a "strong, erect-growing species, varying from two to ten feet high, succulent when young, a splendid grass for a cattle run, though not much sought after by sheep. It is a free seeder. The settlers on the banks of the Hawkesbury (New South Wales) look upon it as a recent importation, and seed of it has been distributed under the name of Panicum speciabile. (WooUs) Coast of Queensland, New South Wales, and Western Australia."
A rhizome of Sorghum halepense
El sorgo de Alepo (Sorghum halepense) es un cereal, producto de una hibridación de introgresión con otra especie del género Sorghum en la familia Poaceae.
El origen del sorgo se localiza en África central (Etiopía o Sudán), pues es en esta zona donde se encuentra la mayor diversidad varietal de la especie. Esta diversidad disminuye hacia el norte de África y Asia. Existen, sin embargo, ciertas evidencias de que surgió de forma independiente tanto en África como en la India. Es precisamente en este último país de donde datan en el siglo I d.C. las primeras referencias escritas. También se encuentran en Siria esculturas que tratan el desarrollo de dicha especie.[1]
No se sabe exactamente cuándo se introdujo la planta por primera vez en América, aunque se asume que las semillas de esta especie llegaron al Nuevo Continente en barcos que transportaban esclavos desde África. Ingresó en Estados Unidos procedente de Turquía hacia 1830. El primer informe escrito de su presencia en México es de 1913, aunque para esa fecha había llegado hasta Yucatán y era una importante maleza en Nuevo León (Alcaraz, 1913).
El nombre científico, Shorgum halepensis (L.) Pers. hace referencia a la ciudad de Haleb (Aleppo) en Siria. Recibe varios nombres comunes: cañota, millaca,[2] hierba johnson, pasto johnson, sorguillo, canuto, pasto ruso, paja johnson, zacate johnson, pasto silvestre, sorgo silvestre, sorgo de Alepo. En Argentina se lo conoce como "maicillo".
Se considera que esta maleza es autógama pero no completa, exhibiendo un 6 a 8 % de alogamia. La dispersión de las semillas puede producirse a través de distintos agentes, como es el agua de irrigación (en los sistemas bajo riego) y también por escorrentía superficial en campos con pendiente en los sistemas de producción de secano. Los herbívoros que consumen esta maleza eliminan las semillas a través de las heces, con diferente nivel de dormición, sin pérdida de viabilidad. Probablemente las aves puedan dispersar a gran distancia esta maleza.
Las dos fuentes principales de dispersión secundaria son los granos o semillas para la siembra contaminadas con esta maleza y el equipo de cosecha: muchas semillas pueden ser transportadas largas distancias desde el sitio original en los distintos enseres del equipo de cosecha (sinfines, volquetes, carros tolvas y vehículos complementarios), los que pueden incluso alojar semillas en la banda de rodamiento de sus neumáticos.
Las semillas recién dispersadas exhiben elevada viabilidad (superior al 85 %) y un alto grado de dormición. En el suelo se suelen encontrar fracciones o subpoblaciones de semillas con diferente nivel de este efecto y diferentes requerimientos para su activación. Este complejo mecanismo evolutivo permite a las semillas no solo detectar la existencia de canopeos, sino también medir la profundidad a la que se encuentran, lo cual está muy relacionado con sus probabilidades de éxito tras la emergencia.
Los rizomas constituyen un mecanismo de propagación muy eficaz y -desde el punto de vista evolutivo- constituyen uno de los pilares de la persistencia de esta mala hierba en una gran variedad de agroecosistemas y amplias latitudes, desde que replican genotipos resistentes y adaptados. Los rizomas constituyen, en promedio, el 30 % de la biomasa total que acumula una planta durante todo su ciclo.
Si se realiza una estimación periódica de la biomasa de rizomas durante todo el año, se obtiene una función de tipo sinusoidal, la cual exhibe valores máximos hacia el fin del verano e inicios del otoño y valores mínimos hacia el fin del invierno e inicios de la primavera. Tanto el consumo de sustrato por respiración durante el invierno, como la removilización de reservas para sustentar el crecimiento de estructuras aéreas (macollas) caracterizan el segmento decreciente de la biomasa de rizomas. Los procesos involucrados en el segmento creciente comprenden a la formación de fotoasimilados y su transporte hacia el sistema subterráneo, con una tasa de acumulación elevada. Durante la etapa de acumulación de biomasa subterránea las concentraciones de los carbohidratos aumentan.
Es importante recalcar que la fracción decreciente se reinicia toda vez que el sistema aéreo se destruye; como consecuencia de la perturbación del sistema de macollas por bajas temperaturas invernales (heladas), a causa de un control mecánico durante la primavera o el verano, por la acción de herbicidas de contacto o por una pobre actividad de un herbicida sistémico.
Aunque muestra marcada preferencia por los climas cálidos, aparece igualmente en zonas más frías. De hecho, tras ser introducida en el sur de Estados Unidos de América como forrajera y comprobarse su proceso de naturalización se pensó que solo afectaría a las regiones de clima templado-cálido, constatándose posteriormente su capacidad para colonizar áreas mucho más frías y extenderse hacia latitudes mucho más septentrionales, llegando actualmente al límite con Canadá. En España aparece tanto en estaciones ruderales como en campos de cultivo, especialmente en los viñedos, cultivos de cítricos, arrozales, campos de remolacha y de maíz, así como en cursos de agua (acequias, canales, etc.).
a) Temperatura: en general se sabe que el desarrollo de las plantas del pasto Johnson, tanto para el crecimiento y desarrollo de la parte aérea como para el de raíces y rizomas, es óptimo a 32 °C.
Para la formación de rizomas existe un límite mínimo de 15 a 20 °C y un límite máximo de 40 °C. Para la germinación de las yemas de los rizomas el máximo es de 39, con un óptimo de 28-30 °C y un mínimo de 15 °C. Se sabe que la temperatura máxima que soportan los rizomas es de 50 a 60 °C por espacio de 3 días, cuando se localizan a 2.5 cm de profundidad en el suelo. Su tolerancia a las bajas temperaturas aumenta con la profundidad a la que se encuentran enterrados los rizomas y bajas temperaturas edáficas limitan la expansión de la especie,[3] mientras que la floración está regulada por la temperatura y no por los factores nutricionales.[4]
Se necesita una temperatura sostenida de -9 °C para causar la muerte de los rizomas de esta especie, sobreviviendo al frío si se localizan a 20 cm o más de profundidad en el suelo.[5] Respecto a la germinación de semillas, esta es nula a 10-15 °C, siendo su óptimo de 39 °C.[6]
b) Luz: se ha podido demostrar que el sorgo tiene un desarrollo óptimo con un fotoperíodo de alrededor de 12 a 13 horas. Para un fotoperíodo de 12 horas, el crecimiento de esta gramínea es óptimo a 27 °C, pese a que en las etapas iniciales el crecimiento sea óptimo a 32 °C.
En otro estudio se encontró que mediante la interrupción del periodo oscuro de 8 h, las plantas de sorgo no florecen y su producción de rizomas disminuye grandemente, sin afectar la producción de raíces, proponiendo esta estrategia como un posible medio para evitar la diseminación de la especie.
c) Profundidad y tipo de suelo: prefiere suelos profundos, sin exceso de sales, con buen drenaje, sin capas endurecidas, de buena fertilidad y un pH que varía de ligeramente ácido a alcalino.
Existen diferencias en cuanto a la producción y distribución de los rizomas de acuerdo a la textura del suelo,[7] en un suelo franco-arenoso, la producción de rizomas fue casi el doble que en un suelo arcilloso. En un suelo franco-arcilloso-limoso la producción de rizomas fue 10% menor que en el anterior. Además se encontró que un suelo arcilloso el 80% de los rizomas se localizan en los 7.5 cm de la superficie del suelo, contrastando con el mismo estrato en un suelo franco-arenoso, siendo la emergencia de rizomas mayor en este tipo de suelos que en un suelo arcilloso.
d) Agua: Requerimiento en el ciclo:
Requerimiento en el ciclo mm Óptimo 400-550 Conveniente 350 Mínimo 250Es fundamental que el suelo tenga una adecuada humedad en el momento de la germinación para que se dé una emergencia rápida y homogénea. Las mayores exigencias en agua comienzan unos 30 días después de emergencia y continúan hasta el llenado de los granos, siendo las etapas más críticas las de panojamiento y floración.
Con frecuencia, en una campaña se cosechan dos o tres cortes de heno; es un pasto valioso, pero las plantas jóvenes pueden contener cantidades notables de HCN, y por lo tanto debe pastarse con prudencia.
Como % de materia seca[8] MS PB FB Cen. EE ELN Ref. Fresco, 6 semanas, India 15.9 16.1 29.6 11.1 2.8 40.4 190 Fresco, 10 semanas, India 20.9 12.7 34.1 9.9 2.6 40.7 190 Fresco, 14 semanas, India 27.7 7.4 38.7 9.2 1.6 43.1 190 Fresco, primer corte, India 10.3 35.9 8.2 2.3 43.3 436 Fresco, segundo corte, India 5.1 36.4 9.4 1.5 47.6 436 Heno, Estados Unidos 87.7 6.6 34.6 5.9 1.9 51.0 146 Digestibilidad heno (%) Animal PB FB EE ELN EM Ref. Caprinos 45.0 58.0 40.0 54.0 1.91 146Leyenda: MS (Materia seca), PB (Proteína bruta), Cen. (cenizas), EE (extracto etéreo), ELN (extracto libre de nitrógeno), FB (fibra bruta), Ref. (Referencia)
A pesar de ser un buen forraje, como se ha mencionado presenta el inconveniente de tener un glucósido cianogénico tóxico llamado "dhurrina" que se incrementa en condiciones de sequía, helada, alto contenido de nitrógeno y bajo contenido de fósforo en el suelo, además de ser más común en plantas jóvenes. Los casos de envenenamiento son más frecuentes en ganado vacuno y se pueden evitar mediante el ensilaje, proceso en el cual la dhurrina es inactivada. Los animales afectados por su consumo en fresco presentan dolores de abdomen. Las aves pueden consumirla sin que les produzca efectos adversos.
El sorgo de Alepo es una de las 10 malas hierbas más dañinas a la agricultura mundial,[9] ocupando esta el sexto lugar, localizándose en áreas templadas, subtropicales y tropicales del sur de Estados Unidos, México, centro y Sudamérica, zona mediterránea de Europa, África, India y Australia.
Las plantas que cuentan con este tipo de asimilación toleran altas intensidades lumínicas, altas temperaturas, baja concentración de CO2 y alta concentración de O2 en la atmósfera sin afectar su proceso fotosintético, además de que no presentan el fenómeno de fotorrespiración por lo que son altamente competitivas.
Estos sorgos son plantas C4, debiendo en gran parte su agresividad a esta cualidad. De esta forma, algunas autores afirman que una ingesta de sorgo de Alepo en maíz reduce 2/3 partes del peso seco del grano,[10] y 60-100 kg/ha de potasio. De la misma manera, las infecciones de esta hierba parásita en maíz reducen el crecimiento y tamaño del cultivo retardando la diferenciación de los órganos vegetativos y reproductivos,[11] y reduce el área de las hojas y el tamaño de las mazorcas, causando esterilidad de muchas flores debido a la competencia entre ambas. El pasto de Johnson puede reducir en más del 45 % los rendimientos de caña de azúcar y soya.[12]
Actúa como hospedante de un díptero plaga conocido como mosquito del sorgo (Contarinia sorghicola,[13] Cecidomyiidae) bastante específico del sorgo cultivado que hiberna en las semillas de la mala hierba, desde donde infecta al cultivo. Se considera también un contaminante del polen del sorgo cultivado y un hospedante del virus del mosaico de la caña de azúcar (de ahí la bajada de rendimiento). Además es hospedera alternante de otras importantes plagas y enfermedades como son: el mildiú velloso (Aclerospora sorghi) y el antracnosis (Colletotrichum graminicolum).
Debido a que su presencia se circunscribe a entornos agrícolas es suficiente con considerar las prácticas llevadas a cabo habitualmente en este tipo de medios. Es esencial desarrollar estrategias preventivas que contemplen el uso de semillas o mezclas de éstas (como las empleadas habitualmente en la creación de céspedes forrajeros) y de sustratos absolutamente exentos de propágulos de esta especie.
El arranque manual puede efectuarse por medio de herramientas agrícolas, tales como cultivadoras azadas, arados, rotator y etc. Este tipo de control arranca la hierba a la vez que se remueve el suelo pudiendo beneficiar al cultivo al extraer los rizomas. No obstante, el uso de control mecánico en especies de malas hierbas perennes es limitado debido a que se reproducen vegetativamente. Con el sorgo de Alepo las posibilidades de éxito con este tipo de control son muy limitadas ya que se ha demostrado que una planta proveniente de semilla o rizoma, de más de 20 días de edad, soporta 8 cortes semanales consecutivos sin morir.
En algunos terrenos se acostumbra rastrear los terrenos infestados con esta maleza para exponer sus rizomas al medio y causar su muerte por desecación o daños de heladas.[3] Sin embargo, se ha observado que los rizomas de esta especie soportan una desecación de hasta un 75% de su peso fresco sin perder su viabilidad. Además estos órganos toleran -9 °C sin morir, por lo que este tipo de prácticas no aseguran un buen control de esta maleza y pese a que pueden ser eficientes, se requiere de una cantidad extraordinaria de mano de obra, lo cual se refleja en un mayor coste.
La inundación es una opción viable en algunas zonas.[14] Hasta el momento no se conocen agentes de control biológicos específicos y efectivos.
El estudio de ciertos biotipos de EE. UU. exhibe resistencia simple y cruzada a los herbicidas graminicidas tipo ACCASE, además de ALS (imidazolinonas) y dinitroanilinas (trifluralina).
En países donde aparece como planta parásita de otros cultivos, principalmente soja, se está convirtiendo en los últimos años en un auténtico problema por los altos niveles de resistencia que presenta a herbicidas, y concretamente, a glifosato. En la siguiente publicación argentina de alertas de malezas[15] se puede leer lo siguiente:
El control debe asentarse en el cumplimiento oportuno y sistemático de cuatro objetivos básicos:
a) Destruir la población de yemas existentes en los rizomas. b) Impedir la formación de nuevos rizomas. c) Impedir la producción y/o aportes de semillas. d) Disminuir la población de semillas en el banco, y en los productores de semillas.
Los cuatro objetivos deben enmarcarse en el programa de rotaciones o secuencias de cultivos y sus respectivos barbechos, de manera de optimizar tanto las tácticas de control como la habilidad competitiva de los cultivos. La detección y eliminación temprana de los focos de invasión y la prevención constituyen las mejores inversiones, las que bajo formas y metodologías relativamente sencillas, pueden evitar la diseminación de la maleza en todo el campo.
Datos: Q858360
Multimedia:
Especies: Sorghum halepense
El sorgo de Alepo (Sorghum halepense) es un cereal, producto de una hibridación de introgresión con otra especie del género Sorghum en la familia Poaceae.
Jonsonindurra (Sorghum halepense) on 1–2 metriä korkeaksi kasvava heinälaji, joka muistuttaa viljana viljeltyä durraa eli kirjodurraa (Sorghum bicolor). Siitä poiketen jonsonindurra on monivuotinen ja tekee maarönsyjä. Sen tähkylät varisevat röyhystä jyvien kypsyessä.[1]
Jonsonindurra kasvaa alkuperäisenä Pohjois-Afrikassa ja Aasian länsiosassa. Suomessa lajia on tavattu satunnaistulokkaana muutamia kymmeniä kertoja, varsinkin 2010-luvulla.[2]
Jonsonindurra (Sorghum halepense) on 1–2 metriä korkeaksi kasvava heinälaji, joka muistuttaa viljana viljeltyä durraa eli kirjodurraa (Sorghum bicolor). Siitä poiketen jonsonindurra on monivuotinen ja tekee maarönsyjä. Sen tähkylät varisevat röyhystä jyvien kypsyessä.
Jonsonindurra kasvaa alkuperäisenä Pohjois-Afrikassa ja Aasian länsiosassa. Suomessa lajia on tavattu satunnaistulokkaana muutamia kymmeniä kertoja, varsinkin 2010-luvulla.
Sorghum halepense, le sorgho d'Alep, est une espèce de plantes monocotylédones de la famille des Poaceae (Graminées), sous-famille des Panicoideae, originaire du bassin méditerranéen.
Le sorgho d'Alep est une plante herbacée vivace à répartition quasi-cosmopolite, qui est parfois cultivée comme plante fourragère, mais qui est surtout une mauvaise herbe des cultures très envahissante et très difficile à combattre, considérée comme particulièrement nuisible dans 53 pays.
Elle se caractérise par son système de rhizomes très expansif et par sa forte capacité à se reproduire par graines. Cette plante a des effets néfastes sur la production agricole, par sa très forte compétitivité vis-à-vis des plantes cultivées et sa toxicité pour les herbivores. Elle tend à réduire la fertilité des sols et peut servir d'hôte-réservoir pour divers agents phytopathogènes. En outre, ses peuplements présentent des risques d'incendie en période sèche.
Noms vernaculaires : herbe de Cuba, herbe de Guinée, houlque d'Alep, sorgho d'Alep, sorgho fourrager[1].
Le sorgho d'Alep est une plante herbacée (graminée) généralement vivace par ses rhizomes robustes. Ceux-ci se situent dans la couche superficielle du sol, à moins de 20 cm de profondeur, mais peuvent descendre plus bas dans les sols profonds. Ils peuvent atteindre 2 m de long, avec un diamètre de 1 à 2 cm. Ils s'enracinent souvent au niveau des nœuds et forment un tapis enchevêtré, dense et résistant. Les rhizomes servent d'organe de stockage de glucides et permettent la régénération de la plante. Cependant, l'espèce présente une grande variabilité, avec de nombreux écotypes, et peut se développer comme une plante annuelle dans les climats chauds et arides et à la limite nord de son aire de répartition[2].
Les tiges (chaumes), dressées, tomenteuses au niveau des nœuds, peuvent atteindre 1,5 m de haut. Toutefois la hauteur totale de la plante en période de floraison peut atteindre jusqu'à 3,5 m[2].
Les feuilles au limbe très allongé, de 1 à 1,5 cm de large en moyenne, à la nervure centrale proéminente, ont une gaine glabre et une ligule ciliée-membraneuse de 2 mm de long[3].
L'inflorescence est une panicule de 15 à 60 cm de long. Elle regroupe de 35 à 350 épillets selon les écotypes. . Ces épillets, aigus, longs de 5 à 7 mm, sont jumelés, l'un est sessile et parfait, l'autre est pédicellé et staminé. La première glume est raide. Les lemmes fertiles sont aristées, avec une arête courte de 1 à 15 mm, ou sans arête.
Les grains ovales-oblongs, de 4 à 7 mm de long sur 2 à 3 mm de large, conservent leurs glumes, de couleur brun rougeâtre à noir brillant, à maturité (grains vêtus)[3].
Cette espèce compte deux types de variétés qui se distinguent par leur nombre chromosomique, soit 2n = 20 ou 40[3].
Cette espèce est considérée comme étant autogame, mais pas complètement, avec une part de 6 à 8 % d'allogamie.
La dispersion des graines se fait naturellement par l'intermédiaire de différents agents, comme les eaux de ruissellement dans les terrains en pente, ou les eaux d'irrigation. Les herbivores qui mangent ces graines peuvent les éliminer dans leurs selles, avec différents niveaux de dormance sans perte de viabilité. Les oiseaux peuvent probablement contribuer à les disperser à grande distance.
Les deux principales causes de dispersion secondaire, souvent à très grande distance, sont le fait de l'homme, par les semences contaminées par ces graines de mauvaise herbe d'une part, et les matériels de culture et de récolte, qui s'ils sont mal nettoyés peuvent transporter des graines d'un site à un autre, par exemple par l'intermédiaire des pneumatiques.
Les graines qui viennent d'arriver à maturité et sont dispersées dans le sol présentent une viabilité élevée (plus de 85 %) et un degré élevé de dormance. Dans le sol, on trouve généralement différentes fractions ou sous-populations de graines qui sont à des stades différents de dormance et qui requièrent des exigences différentes pour leur activation. Ce mécanisme évolutif complexe entraîne une réaction adaptée des graines présentes dans le sol en fonction de la présence ou non d'un ouvert végétal, de leur profondeur d'enfouissement, facteurs qui conditionnent la réussite en cas de germination.
Les rhizomes sont un mécanisme de propagation très efficace et, du point de vue de l'évolution, ils constituent l'un des piliers de la persistance de cette mauvaise herbe dans différents écosystèmes agricoles à des latitudes diverses, car ils reproduisent des génotypes résistants et adaptés. Les rhizomes représentent, en moyenne, 30 % de la biomasse totale accumulée par une plante tout au long de son cycle biologique.
La biomasse des rhizomes varie en cours d'année, selon une fonction de type sinusoïdal, qui présente des valeurs maximales à la fin de l'été et au début de l'automne et des valeurs minimales vers la fin de l'hiver et le début du printemps. La consommation de substrat par la respiration pendant l'hiver, comme la remobilisation des réserves pour soutenir la croissance des structures aériennes (talles) caractérisent la phase de diminution de la biomasse des rhizomes. Les processus impliqués dans la phase de croissance comprennent la formation de photoassimilés et le transport vers le système racinaire, avec un taux élevé d'accumulation. pendant la phase d'accumulation de la biomasse souterraine, les concentrations d'hydrates de carbone augmentent.
La phase décroissante redémarre chaque fois que le système aérien est détruit, du fait de la perturbation du système des talles par les gelées d'hiver, par des coupes mécaniques au cours du printemps ou en été, par l'action d'herbicides.
Selon Catalogue of Life (23 février 2016)[4] :
Le sorgho d'Alep est originaire du bassin méditerranéen (Europe méridionale, Afrique du Nord et vraisemblablement Asie Mineure et Proche-Orient). Il s'est répandu et naturalisé dans le monde entier dans les régions de climat tempéré chaud et subtropical, entre les latitude 55 ° N et 45 ° S. Il est largement introduit en Amérique du Nord, en Europe, en Afrique et en Asie sud-occidentale, ainsi qu'en Amérique du Sud (Brésil, Argentine) et dans le nord de l'Australie.
En Amérique du Nord, on le rencontre dans la presque totalité des États-Unis (sauf dans le Maine), au Canada en Ontario et au Mexique de la région du delta du Rio Grande (Tamaulipas) à la région du Cap (Basse-Californie du Sud). Il s'est établi également dans les Antilles et à Hawaï[2].
Cette espèce a été introduite en Caroline du Sud depuis la Turquie vers 1830. Son nom anglais de Johnson grass fait référence au colonel William Johnson de Selma (Alabama), qui en fit la culture comme plante fourragère dans la vallée de la rivière Alabama dans les années 1840[2].
Sorghum halepense, le sorgho d'Alep, est une espèce de plantes monocotylédones de la famille des Poaceae (Graminées), sous-famille des Panicoideae, originaire du bassin méditerranéen.
Le sorgho d'Alep est une plante herbacée vivace à répartition quasi-cosmopolite, qui est parfois cultivée comme plante fourragère, mais qui est surtout une mauvaise herbe des cultures très envahissante et très difficile à combattre, considérée comme particulièrement nuisible dans 53 pays.
Elle se caractérise par son système de rhizomes très expansif et par sa forte capacité à se reproduire par graines. Cette plante a des effets néfastes sur la production agricole, par sa très forte compétitivité vis-à-vis des plantes cultivées et sa toxicité pour les herbivores. Elle tend à réduire la fertilité des sols et peut servir d'hôte-réservoir pour divers agents phytopathogènes. En outre, ses peuplements présentent des risques d'incendie en période sèche.
Noms vernaculaires : herbe de Cuba, herbe de Guinée, houlque d'Alep, sorgho d'Alep, sorgho fourrager.
Piramidalni sirak (kukuruzar, alepski sirak, piramidasti sirak, lat. Sorghum halepense), trajnica iz porodice trava, rod sirak, raširena od Makaronezije preko sjeverne Afrike, jugozapadne i središnje Azije do Indokine, a danas se nalazi gotovo po cijelom svijetu.
Ima uspravnu glatku stabljiku koja naraste do 2 metra visine. Ime je dobila po metličastim cvatovima na vrhovima stabljika koji su piramidalnog oblika. Cvate od lipnja do rujna. Plod je pšeno, a jedna biljka u sezoni proizvede 1500 do 1800 sjemenki. Kako je česta na kultiviranim zemljištima smatraju je korovom. Štetna je za kukuruzišta jer je domaćin nekim biljnim ušima i nematodama koje parazitiraju na kukuruzu. Piramidalni sirak luči i tvari koje sprječavaju klijanje drugih biljaka a djeluje inhibitorno i na bakterije koje ispuštaju dušik u tlo.[1]
S. halepense
S. halepense
S. halepense
S. halepense
S. halepense
S. halepense
Sorgo selvatico o Sorghetta, Sorghum halepense, è una pianta erbacea della famiglia delle Poaceae, originaria del Mediterraneo che si è diffusa in Europa e Medio Oriente. È stata introdotta in tutti i continenti ad eccezione dell'Antartide. Si riproduce attraverso rizoma e seme.
È stata a volte utilizzata come foraggio e per arrestare l'erosione del suolo, ma è considerata una specie infestante:
È comune in colture, pascoli e campi abbandonati, margini delle strade, argini fluviali e ai bordi di boschi e siepi. Ama suoli smossi, lavorati, fertili e profondi, comuni nelle culture erbacee. È resistente a molti diserbanti comuni, e sono emerse varietà resistenti al glifosato in Argentina e Stati Uniti.[1][2][3] È considerata una delle peggiori specie invasive al mondo.[4]
Il nome americano Johnson grass è legato a quello del Colonnello William Johnson, che la piantò in Alabama nel 1840. La pianta si era già affermata in molti degli Stati Uniti già il decennio successivo.[5][6]
Sorgo selvatico o Sorghetta, Sorghum halepense, è una pianta erbacea della famiglia delle Poaceae, originaria del Mediterraneo che si è diffusa in Europa e Medio Oriente. È stata introdotta in tutti i continenti ad eccezione dell'Antartide. Si riproduce attraverso rizoma e seme.
È stata a volte utilizzata come foraggio e per arrestare l'erosione del suolo, ma è considerata una specie infestante:
Le foglie danneggiate da freddo o caldo intensi sono fonte di acido cianidrico dannoso per gli animali Le foglie possono causare accumulo di gas nell'apparato digerente degli erbivori a causa di un eccessivo accumulo di nitrato È una specie invasiva a rapida crescita che sottrae nutrienti e acqua alle coltureÈ comune in colture, pascoli e campi abbandonati, margini delle strade, argini fluviali e ai bordi di boschi e siepi. Ama suoli smossi, lavorati, fertili e profondi, comuni nelle culture erbacee. È resistente a molti diserbanti comuni, e sono emerse varietà resistenti al glifosato in Argentina e Stati Uniti. È considerata una delle peggiori specie invasive al mondo.
Il nome americano Johnson grass è legato a quello del Colonnello William Johnson, che la piantò in Alabama nel 1840. La pianta si era già affermata in molti degli Stati Uniti già il decennio successivo.
Sorghum halepense é uma espécie de planta com flor pertencente à família Poaceae.
A autoridade científica da espécie é (L.) Pers., tendo sido publicada em Synopsis Plantarum 1: 101. 1805.[1]
É conhecido popularmente como maçambará, peripomonga e sorgo-de-alepo. É uma gramínea que ocorre em regiões tropicais. Possui colmos altos e grossos e folhas compridas com cerca de oitenta centímetros de comprimento por dois a quatro centímetros de largura. Suas flores formam panículas piramidais que florescem no primeiro ano. Pode ser de cultivo anual ou perene.[2]
"Maçambará" é oriundo do termo quimbundo masã'bala.[3] "Peripomonga" deriva do tupi peripo'mong, "junco pegajoso".[4] "Sorgo-de-alepo" é uma referência à cidade de Alepo, na Síria.
Trata-se de uma espécie presente no território português, nomeadamente em Portugal Continental, no Arquipélago dos Açores e no Arquipélago da Madeira.
Em termos de naturalidade é introduzida nas três regiões atrás referidas.
Encontra-se/Não se encontra protegida por legislação portuguesa ou da Comunidade Europeia, nomeadadamente pelo Anexo da Directiva Habitats e pelo Anexo da Convenção sobre a Vida Selvagem e os Habitats Naturais na Europa e pelo .
Sorghum halepense é uma espécie de planta com flor pertencente à família Poaceae.
A autoridade científica da espécie é (L.) Pers., tendo sido publicada em Synopsis Plantarum 1: 101. 1805.
É conhecido popularmente como maçambará, peripomonga e sorgo-de-alepo. É uma gramínea que ocorre em regiões tropicais. Possui colmos altos e grossos e folhas compridas com cerca de oitenta centímetros de comprimento por dois a quatro centímetros de largura. Suas flores formam panículas piramidais que florescem no primeiro ano. Pode ser de cultivo anual ou perene.
Ogräsdurra (Sorghum halepense) är en art i familjen gräs. Ogräsdurran förekommer i Medelhavet, Europa och Mellanöstern.
Ogräsdurra används för att binda mark och minska erosion. Den uppfattas som ett ogräs eftersom;
I Argentina orsakar plantan problem till följd av ökad resistens.[1]
Ogräsdurra (Sorghum halepense) är en art i familjen gräs. Ogräsdurran förekommer i Medelhavet, Europa och Mellanöstern.
Ogräsdurra används för att binda mark och minska erosion. Den uppfattas som ett ogräs eftersom;
Om det utsätts för frost eller hetta kan det bilda blåsyra i tillräckligt stor mängd för att vara dödligt för boskap och hästar. Bladverket kan orsaka blåsor för växtätare på grund av nitrater. Det sprider sig snabbt och kan kväva planterade grödor.I Argentina orsakar plantan problem till följd av ökad resistens.
Со́рго але́пське або гума́й (Sorghum halepense (L.) Pers.) — рослина родини тонконогових (Poaceae)/
Багаторічний коренепаростковий бур'ян, теплолюбний, віддає перевагу пухким, родючим ґрунтам, не витримує засолених, сухих і щільних ґрунтів. Батьківщина гумаю — країни Середземномор'я, Близький Схід. широко розповсюджене в країнах з тропічним і субтропічним кліматом. Засмічує всі культури, сади, виноградники. Рослина отруйна.
Цвіте з першого року життя в липні-серпні. Плодоносить у серпні-жовтні. Одна рослина утворює до 10 000 зернівок. Насіння має глибокий і розтягнутий період спокою, завдяки щільній оболонці зберігають життєздатність до 5 років. При зберіганні насіння в гної, силосі чи у воді, вони втрачають здатність до проростання. Розмножується як насінням, так і корневищами.
Входить до 18-ти найбільш шкідливих бур'янів світового землеробства. Використовується у світі на фураж та у боротьбі з ерозією. Молоді пагони насичені ціанистими сполуками можуть викликати падіж великої рогатої худоби та коней. Через велику швидкість росту здатен до заміщення інших злаків у біоценозах.
Головний шлях розростання бур'яну — відростання з кореневищ, тому заходи боротьби повинні враховувати необхідність знищення і насіння, і кореневищ. Глибока зяблева оранка в результаті якої кореневища вивертаються на поверхню і засихають (в теплий період року), або вимерзають (зимою) — один з найефективніших методів знищення бур'яну. При температурі -30°—35ºС протягом 7 днів та —10°—12ºС декілька днів кореневища повністю втрачають здатність до життєдіяльності. Одночасно з цим використовується розрізування дискуванням та глибоке загортання кореневищ а також пригнічення бур'яну посівами високо конкурентних культур: озимої пшениці, озимої вики, люцерни.
З гербіцидів для боротьби з бур'яном використовуються: Фурорі супер А (для боротьби лише з сорго алепським), гліфосати та їх аналоги — Раундап, Утал, Фарсі, Фосуленд, Глісол, що застосовуються чітко за інструкціями до них. Гліфосати та їх аналоги знищують також свинорий, пирій повзучий та більшість дводольних бур'янів. Препарати діють краще за умови, коли висота стебла бур'яну 20—30 см, листова поверхня його велика (частіше це червень). При обробках необхідно, щоб гербіцид потрапляв лише на рослини бур'яну інакше він зашкодить і культурним рослинам.
Останнім часом спостерігається проблема розвитку резістентних до гліфосатів форм, наприклад в Аргентині[1][2].
В Україні вперше було накладено карантин по даному бур'яну в Одеській області в 1 господарстві на площі 55 га, у 2003 році. В результаті обстежень у 2006 році виявлено нові осередки сорго алепського у Тарутинському та Арцизькому районах, де і надалі можливе розширення ареалу цього бур'яну. Площа зараження бур'яном склала 760 га.
Це незавершена стаття про Тонконогові.Sorghum halepense là một loài thực vật có hoa trong họ Hòa thảo. Loài này được (L.) Pers. miêu tả khoa học đầu tiên năm 1805.[1]
Sorghum halepense là một loài thực vật có hoa trong họ Hòa thảo. Loài này được (L.) Pers. miêu tả khoa học đầu tiên năm 1805.
Sorghum halepense (L.) Pers., 1805
Сорго алеппское (лат. Sórghum halepénse), также гума́й, Джонсонова трава, — травянистое растение, вид рода Сорго (Sorghum).
Многолетний злак, выращиваемый на фуражное зерно. Обременительный сорняк, в ряде регионов признан инвазивным видом.
Многолетнее травянистое растение с мясистыми ползучими корневищами до 1 см толщиной. Стебли до 3 м высотой, то 2 см толщиной, в нижней части нередко с придаточными корнями, в узлах иногда волосистые.
Листья 20—60 см длиной, 1—3 см шириной, голые, с ясно выраженными жилками. Влагалища голые, ребристые, открытые, с налегающими друг на друга краями. Язычок плёнчатый, по краю реснитчатый, до 5 мм длиной.
Соцветие — крупная многократно разветвлённая продолговатая метёлка 15—50 см длиной, часто с фиолетовым оттенком. Веточки метёлки до 25 см длиной, на ближайших к основанию нескольких сантиметрах обычно без колосков. Колоски обычно в парах, на верхних веточках часто по три. Один из колосков в группе сидячий, с обоеполым цветком, а другие — бесполые или с тычиночным цветком, на ножках. Плодущий колосок волосистый, яйцевидный, около 5 мм длиной, обычно с изогнутой остью 1—2 см длиной. Бесплодные колоски более узкие, 5—7 мм длиной. Колосковые чешуи, покрывающие зерновку, красно-коричневые до чёрных, блестящие.
Первоначальный ареал растения точно не установлен. Наиболее узкая область, указываемая в качестве предположительного исконного ареала растения — Юго-Восточная Европа. Другие авторы включают сюда также Средиземноморье (включая Северную Африку) и Западную Азию.
В настоящее время растение распространилось по всем континентам (кроме Антарктиды). Даты интродукции растения в Европу и Северную Америку не установлены. К началу XIX века растение, по-видимому, изредка выращивалось на юго-востоке США, к 1830-м годам стало весьма популярным кормовым растением в США. К началу XX века растение стало считаться опасным сорняком в США. В Северной Европе сорго алеппское впервые появилось в 1914 году в Дании. В Австралии впервые стало выращиваться в 1871 году в Ботаническом саду Аделаиды, в 1883 году впервые отмечено одичавшим в Новом Южном Уэльсе.
Растение признано инвазивным видом в Индонезии, Таиланде, на Филиппинах, в ряде штатов США, на Кубе, в Никарагуа, Чили, Колумбии, Перу, в Новой Зеландии, на ряде островов Тихого океана.
Во многих субтропических регионов выращивается на фуражное зерно. В некоторых регионах используется для противоэрозионной стабилизации грунтов.
Пыльца растения является аллергеном.
Гомотипные:
Гетеротипные:
и другие.
Сорго алеппское (лат. Sórghum halepénse), также гума́й, Джонсонова трава, — травянистое растение, вид рода Сорго (Sorghum).
Многолетний злак, выращиваемый на фуражное зерно. Обременительный сорняк, в ряде регионов признан инвазивным видом.
石茅（学名：Sorghum halepense）又名约翰逊草(英语：Johnson grass)、假高梁，为禾本科高粱属下的一个种。
.jpg)
.jpg)
.jpg)
.jpg)
|access-date=中的日期值 (帮助)
这是一篇與植物相關的小作品。你可以通过编辑或修订扩充其内容。 
S. halepense (L.) Pers. var. propinquum (Kunth) Ohwi
S. propinquum (Kunth) Hitchc.
セイバンモロコシ（学名：Sorghum halepense）（西播蜀黍）はイネ科の普通に見られる雑草の一つ。英語名はジョンソングラス。
セイバンモロコシは単子葉植物イネ科モロコシ属の多年生植物である。草丈は0.5-2m程度になり、地下の根茎を伸ばして群生する。葉は細長く縁はざらつかない。夏から秋に円錐花序の多数の小穂をつけた15-50cmの穂を出す。小穂には毛があり、長さ4-6mmで有柄と無柄のものが混じる。
一般的に使用されるグリホサート除草剤に薬剤抵抗性をもつものの出現がアルゼンチンとアメリカ合衆国で報告されている[1][2][3]。
地中海地域のヨーロッパ中東原産で1945年頃に侵入した帰化植物である。日本では東北以南に分布し、畑地、牧草地、道端、河川敷、果樹園、荒地などに生え、世界の熱帯から温帯地域に分布する。
霜や乾燥などのストレスによりシアン化水素を植物体内に生産することや、硝酸塩を含むことから、日本では飼料としてほとんど栽培されない[4]。根茎、種子の両方で繁殖するため、畑地・牧草地の強害雑草となっている。
