Study on yield of wheat (t. Aestivum l.) Cultivars with different growth habits in two planting dates for determination of the proper type of cultivars for cold regions of dryland areas

This study was conducted on nine bread wheat genotypes from three different class of growth habit (spring, facultative and winter) in two different planting dates (early planting in early October and late planting in late November), in Maragheh region during three consecutive cropping seasons (1995-1998). Maragheh is a cold dry area with average percipitation of 365mm and altitude of 1720 m above sea level, located at 46°, 30' eastern longitude and 37°, 15' north latitude in north west of Iran. The experimental design was split plot based on R.C.B.D. with 3 replications, in which the main and sub-plots were allocated to the planting dates (First planting date, late September Second planting date, early November), and genotypes (nine genotypes) respectively. Results obtained from group comparison (orthogonal) showed that during the experimental years (3 years), the average yield of winter growth habit genotypes was significantly (?= 1%) higher than those of spring and facultative growth habits. According to the results, in dry and cold areas of north west of Iran, bread wheat lines with winter growth habit can be recommended for planting and wheat improvement strategies for such locations should be based on producing the winter type cultivars.