The Effect of rye (Secale cereale) and Wild Mustard (Sinapis arvensis) Competition on Yield of Sayson and Alvand Wheat (Triticum aestivum) Cultivars and Seed Production Ability of Weeds

This research carried out as two separate factorial experiments based on a randomized complete block design with three replications in 2008-2009 at Agricultural Faculty of Bu-Ali Sina University. Alvand and Sayson wheat cultivars were one of the experimental treatments in both experiments. Rye density was 0، 20، 40، 60 and 80 plants m-2 and wild mustard density was 0، 8، 16، 24 and 32 plants m-2. The results showed that reduction of biological and grain yield of Alvand cv. in weed interference was les than Sayson cv. Seed production and rate of population increasing of both weed species in interference with Alvand cv. in whole densities were less than Sayson cv. Damage of wild mustard individual plant on biological and grain yield of wheat in elevated weed densities was more than grass weed of rye. Also، its ability of seed production in competition with both wheat cultivars was higher than rye. Wild mustard in interference with Alvand cv. had less biological yield، but its harvest index in competition with both cultivars was so closed to rye، and reproduction ability of wild mustard per unit of dry matter elevated weed densities in competition with both wheat cultivars was the same. Wild mustard had very higher ability of seed production than rye based on dry matter unit or weed plant density. Rate of population increasing of both weed species reduced by increasing their seed density. Biological yield of weed than its plant density was the better indicator for estimating weed seed production in interference with wheat.