Determination of Optimum Sowing Date for Bread Wheat (Triticum aestivum L.) Cultivars with Different Flowering Habits in Neishabour

To determine the optimum sowing date for bread wheat cultivars of different flowering habits (spring, facultative and winter), a field experiment was conducted in Neishabour in 2003-04 and 2004-05 cropping seasons, using split plot arrangements in a randomized complete block design with three replications. Three sowing dates were assigned to main plots Oct. 12(D1), Nov. 06(D2) and Dec. 01(D3). Six cultivars Pishtaz, Marvdasht (spring), Alvand, Toos (facultative) and Alamoot, MV17 (winter type) were randomized in sub-plots. Results of combined analysis of variance showed no significant differences for grain yield in different planting dates. However simple analysis of variance showed that in first year D1 produced more grain yield (8804 kg/ha) and in second year D3 was of higher grain yield (7707 kg/ha), due mainly to air temperatures below zero (-7 ° C) in spring in second year, and severe damages imposed to early sowing date. With delay in sowing date, grain yield of winter cultivars decreased more than others, because spikes/m2 decreased, however, 1000GW slightly increased. Honce, latter component contributed to increase in grain yield. Optimum sowing date for winter and spring wheat was determined as early October and early November, respectively. In conlusion, spring type cultivars are recommended in Neishabour for best performance, because they produce higher grain yield in comparison to winter type.