اثر تاريخ كاشت بر فنولوژي ، اجزاي عملكرد و عملكرد دانه دو رقم آفتابگردان

Effect of planting date on phonology, grain yield and its components of two sunflower cultivars

Effects of different planting on phonology , grain yield and its components of two sunflower cultivars were investigated . In 1996, an experiment was conducted in the experimental field of Azad Islamic University of Gonabad. The experiment was arranged in a randomized complete block design with a split plot layout and four replication .The main plot consist of four planting date ( April 24th , May 9th , May 24th and June 8th ) and sub plots were arranged for two sunflower cultivars ( Record and zaria ) . The results of this experiment showed that there were developmental stages with delay in planting. The Record and zaria required 1755 and 1653 growing degree days (GDD) for their physiological maturity respectively .Effect of planting date on biological yield and number of seeds per head were significant and delay in planting reduced them. However, seed weight was affected by planting date and increased as planting delayed. The maximum grain yield was obtained in April 24 cfor Record and the minimum grain yield was obtained in June 8 th for zaria. On the average, Record and zaria yielded 4773 and 4520 kg/ha, respectively . With the respect to the under condition, planting of Record cultivars in April 21th, is recommended.