Evaluation of Some Characteristics Affecting Competitiveness of Eight Iranian Wheat (Triticum aestivum L.) Cultivarswith Rocket (Eruca sativa Mill.)

Crops that better tolerate weed competition or preempt resources from weeds may reduce dependence on herbicides and benefit an integrated weed management program. A field trail was conducted to determine the morphophysiological characteristics affecting tolerance and weed suppressive ability of some winter wheat cultivars in competition with Rocket. The experimental treatments consisted of eight wheat cultivars; kept under weed free and weed infested conditions in a randomized complete block design with a factorial arrangement. The results indicated that Correspondence to: deihim59@yahoo.comand deihim@sbu.ac.ir cultivars with greater harvest index (HI) or ability to prevent HI losses in competition with Rocket could balance yield losses and consequently increase their tolerance. Height increase in more competitive cultivars in competition with Rocket, was important in the competitive ability (CA) of these cultivars (as both tolerance and suppressive ability). Those cultivars with higher CA, were taller or had greater rate of stem elongation. Enhancement rate of stem elongation caused an earlier closure of canopy in more competitive cultivars, and consequently through shading on weed, suppressed the Rocket growth. In conclusion, more competitive cultivars possessed a set of characteristics that contribute to their strong competitive ability including high leaf area and vertical leaf area distribution, taller and greater rate of stem elongation, and high early vigor (viability and speed of germination).