مطالعه تغییرات عملکرد دانه، بیولوژیک و شاخص برداشت لاین‌های امیدبخش گندم نان زمستانه و بینابین در شرایط بهینه و تنش خشکی پس از ظهور بساک

In order to evaluate grain yield, biological yield and harvest index of promising winter and facultative bread wheat lines in optimum and post anthesis drought stress conditions , the present investigation was conducted in split plot design using RCBD, with three replications at Torogh field station, Khorasan Agricultural Research Center, during 2008-2010 growing seasons. Main plots were water limited conditions with three levels (L1: Optimum condition, L2: water limited condition using rainshelter from milky grain stage to maturity L3: water limited condition from anthesis stage to maturity). Ten bread wheat lines, suitable for cold and dry regions (V1: (Toos) , V2: (C-81-10) , V3: (pishgam) , V4: (C-84-4) , V5: (C-84-8) , V6:(C-D-85-15) , V7:(C-D-85-9) , V8:(C-D-84-5502), V9:(C-D-85-5502), V10: (C-85-6)) were assigned to subplots. The results showed that water stress (L2 and L3 treatments) decreased grain yield (18.6% and 45.6%, respectively) and biological yield (11.9% and 45.7%, respectively) in compairin with optimum conditions. The results showed that the highest harvest index (HI) is happended in optimum condition (40.95%). The lowest harvest index(HI) was belong to (L3) water limited conditions from anthesis to maturity(36.37 %), due to reduction in water use in post anthesis staegs in compairin with optimum condition. Genotypes V5 and V4 had higher grain yield (7593 and 7170 Kg/ha, respectively) and optimum biological yield and harvest index than other genotypes.