Impact of sowing date on bread wheat kernel quantitative and qualitative traits under Middle East climate conditions

The current study explored the effects of six spring wheat (Triticum aestivum L.) cultivars, four sowing dates (early, timely, late and very late) and their interactions on quantitative and qualitative traits during two cropping years. A combined analysis of variance (ANOVA) indicated that the effect of sowing date was significant on kernel yield and filling period. The quality traits were not significantly affected by the sowing date. Interaction of sowing date x cultivar x year was significant for some quantity and quality traits including yield, filling period, sedimentation value and gluten index. Average kernel yield reduction of all the cultivars, measured under late and very late planting, was 34% and 50% of optimum sown (November) in 2013-2014, and 25% and 38% in 2014-2015, respectively. For most of the studied traits, the effect of year was confirmed on higher level compared to the effect of cultivar or sowing date. The range for cultivar effect was high for thousand kernel weight, medium for gluten index and low for the other traits. The sowing date had the highest contribution to kernel yield followed by filling period and wet gluten, respectively. Negative relationship was observed between quality traits and kernel yield, but quality traits significantly and positively correlated with each other. In summary, the quality and quantity potential of wheat can be exploited by planting it at optimum time.