ارزیابی عملکرد دانه و اجزای آن در ژنوتیپ‌های گندم تحت تأثیر تنش خشکی پس از گل‌دهی

Drought stress is one of the major limiting factors of crop yield. A field experiment was conducted to study the effects of drought stress on yield and yield components of nine bread wheat and one durum wheat genotypes during 2003-2004 growing season. The experiment was designed as two separate randomized complete blocks design with three replicates under well-watered and unwatered conditions during the post-anthesis period. Post-anthesis drought stress reduced the grain yield and yield components in all genotypes. Mean of each trait significantly(p≤%5) decreased under drought stress conditions, except for spikeletes number per spike and ear number per square meter. The highest yield loss was caused by the grain number per ear and 1000- grain weight reduction under drought stress conditions.“Gahar” genotype had the highest grain yield (4149 kg/ha) under drought stress conditions, whereas the highest grain yield (6674 kg/ha) was obtained for “Nikenejad” genotype under optimum conditions. Based on stress susceptibility index, “Koohdasht” and “Boholh-15” genotypes showed the lowest and the highest yield loss in response to drought stress, respectively. Correlation analysis of yield and yield components indicated that, under drought stress conditions, ear number per square meter (r=0.751) and biological yield (r=0.707) had the highest correlation with the grain yield(p≤%5), whereas these traits were grains number per ear(r=0.864) and biological yield (r=0.848) for the well-watered conditions. Therefore, it might be possible to select genotypes for greater grain yield with the means of the traits which have the highest correlation coeficient with the grain yield under each moisture regime. Generally, it appeared that “Gahar”and “Nikenejad” genotypes with greater yield potential might be recommended for agronomic conditions similar to the present investigation.