تاثیر تغییرات مبدا و مقصد بر عملکرد دانه و میزان روغن آفتابگردان

In order to investigate the effect of variation assimilates supply on grain yield and its component, a field experiment was conducted in 2010 at the College of Agriculture in Shiraz University. The experimental design was randomized complete block design (RCBD) with four replications. Treatments were a combination of leaf defoliation (D1= 1/3 lower leaves and D2= 1/3 central leaves) and grain removal (S1= 1/3 marginal and S2= 1/3 central seeds). A check treatment (without leaf defoliation and grain removal) also included in the experiment. Result indicated that seed yield reduced as a result of partial defoliation or grain removal, as well as that the position of removed leaves and grain play an important role in yield. Seed oil percentage of sunflower significantly decreased as a result of grain removal of central, while grain removal marginal had no significant effect on grain yield. Middle leaves removal caused greater reduction in 1000 grain weight and grain yield. Seed yield had a positive and significant (p<0.01) relationship with seed number per head in both leaf (r=0.89) and grain (r=0.91) removal. Seed thinning (great source per each sink) caused lower percentage of empty seed and increased remained-seed weight, it shows that sunflower is source limited in seed developing.