Evaluation of Some Characteristics Affecting Competitiveness of Eight Iranian Wheat Cultivars with Rocket Weed

Crops that better tolerate weed competition or preempt resources from weeds mayreduce dependence on berbicides and benefit an integrated weed managementprogram. A field trail was conducted to determine the morphophysiologicalcharacteristics affecting tolerance and weed suppressive ability of some winter wheatcultivars in competition with Rocket. The experimental treatments consisted of eightwheat cultivars; kept under weed free and weed infested conditions in a randomizedcomplete block design with a factorial arrangement. The results indicated that cultivars with greater harvest index (HI) or ability to prevent HI losses in competitionwith Rocket could balance yield losses and consequently increase their tolerance.Height increase in more competitive cultivars in competition with Rocket, wasimportant in the competitive ability (CA) of these cultivars (as both tolerance andsuppressive ability). Those cultivars with higher CA, were taller or had greater rate ofstem elongation. Enhancement rate of stem elongation caused an earlier closure ofcanopy in more competitive cultivars, and consequently through shading on weed,suppressed the Rocket growth. In conclusion, more competitive cultivars possessed aset of characteristics that contribute to their strong competitive ability including highleaf area and vertical leaf area distribution, taller and greater rate of stem elongation,and high early vigor (viability and speed of germination).