evaluation of improvement of rate and duration of grain filling duration inbreeding processes in wheat cultivars

in order to evaluation of the process of genetic improvement rate and duration of grain filling among wheat cultivars, the field experiments were conducted at the agricultural and natural resource research center of golestan province in the growing seasons of 2007-2008 and 2008-2009. the 16 cultivars were sown in a randomized complete blocks design with three replications. the results showed that wheat cultivars had not changed during breeding activities in order to improve yield in grain weight and duration of grain filling while rate of grain filling was increased. also rate of grain filling was improved %26.19, in 38 years of the release, was observed %0.7 and it improvement. this increase was due to increasing grain number per unit area. in order to positive and significant correlation between grain filling rate and grain yield it seems that selection for high yield and grain filling rate is possible without the need to increase of grain filling duration.