evaluation empirical models of feral rye and wild mustard to predict yield loss of two winter wheat cultivars

this study was carried out to evaluate empirical models of competition, as two separated experiments based on a randomized complete block design with 3 replications at agricultural faculty of bu-ali sina university, in 2008-2009. in both experiments, alvand and sayson cultivar were planted with densities of 450 plants m-2. in the 1st experiment, feral rye (secale cereale) with densities of 0, 20, 40, 60 and 80 plants m-2 were planted. in the 2nd experiment, wild mustard (sinapis arvensis) density was 0, 8, 16, 24 and 32 plants m-2. the results showed that biological and grain yield of sayson in interference with both weed species, were reduced more than alvand. wild mustard in evaluated density treatments showed more damage on wheat in compared to feral rye. study of values observed and predicted of weed density, one and two parameter models of relative leaf area and relative dry weight indicated that two parameter models of relative leaf area and relative dry weight of both weed species was more appropriate factor to predict wheat yield loss.