Read moreĪ new species of Habranthus is described and illustrated. clarazii after defoliation appear determinant incontributing to explain its greater competitive ability and defoliationtolerance when compared with the other two species.Nomenclature of taxa followed. ambigua, greater root length and dry weight increasesinS. tenuis defoliated twiceshowed a greater (p S. Defoliated plantshada similar root length and root dry weight than undefoliated plants in all threespecies, although plants of S. Root length perunitroot dry weight, however, was more than 43% greater (p S. Root length and dry weight weremorethan 96% greater on defoliated and undefoliated plants ofS. Roots were washedfrom soil, root length estimated by the line intercept method, root dry weightdetermined after oven-drying, and root length per unit root dry weightcalculated from the two measured variables. Bags were destructively harvested either 20 days after the firstdefoliation (first sampling) or 56 days after the second defoliation (secondsampling) by digging out soil very carefully around each bag. Since plants were of unequal size among species,root length and root dry weight data are reported on a per green tiller basis.Half of the plants was defoliated to 5 cm stubble height on 17September and/or 12 October, while the other half remained undefoliated(controls). Numbers of green tillers and circumference per plant hadpreviously been determined. On 17 September, soil coreswereremoved from the edge of the plant, metal structures lined with screen mesh(hereafter called bags) were buried in the holes, and root-free soil was placedinto these structures.
tenuis) and undesirable (S.ambigua)perennial grasses was studied in semiarid rangelands of Central Argentina(40☃9′S, 62★4′W) in 1998.
Root proliferation of desirable (Stipa clarazii andS.
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