Effect of Delayed Sowing on Grain Yield and Some Agronomic Traits of Wheat Genotypes

To assess the response of differen wheat genotypes to delayed sowing field experiments were conducted in Khorramabad research station during 2008-2010 growing seasons. Two sowing dates (Nov.10 and Dec.11) as main plots and 16 wheat genotypes as sub-plots were arranged as split plot in randomized complete block design with three replications. Results showed that effect of year, year × sowing date and year × genotype was significant on some characteristics, but the effect of sowing date and genotype was significant for most of traits. Delayed sowing caused reduction of grain m-2, spike m-2, plant height, days to heading and days to maturity and grain yield. Deleyed sowing reduced grain yield about 29 kg ha-1d-1. Durum wheat cv. Dena and bread wheat lines S-83-3, S-83-4 and S-84-14 with average grain yeild of 6148, 6412, 6679 and 6036 kg ha-1, respectively, were suitable for delayed and optimum sowing dates. There was significant positive correlation between grain yield and some of the traits. The highest correlation coefficeint was observed between grain yield and grain m-2 (r = 0.70**). Although there was no significant difference between the average grain yield of durum and bread wheat, genotypes however, changes (%) in grain yield of durum wheat was less than bread wheat in delayed sowing date.