The present investigation was conducted in the educational-researching farm of Islamic Azad University, Miyaneh branch during the growing season of 2014 and 2015 to evaluate the effects of different treatments of leaf removal on different characteristics such as yield and yield components in two early maturing cultivars of sunflower, Megasun, and Hayson36. The experiment design was factorial based on randomized complete block design with 3 replications. In addition, shrub morphological and physiological characteristics, shrub dry weight, chlorophyll contents, leaf area index (LAI), harvesting index (HI), and oil yield were studied. The results showed a significant difference between various treatments of defoliation, yield components, and studied traits. Moreover, no statistically significant difference was observed between the cultivated cultivars in the study parameters including the head diameter, chlorophyll content, LAI, HI, the 1000-grain weight, seedlessness percentage, and seed and oil yield. In this experiment, the interaction effect of different defoliation treatments and cultivars with studied traits other than the head diameter, chlorophyll contents, HI, seed number, and the 1000-grain weight were not significantly different. The correlation coefficients traits reduce grain and oil yield treatments to remove the whole leaves in the middle one-third reduction stems from two factors filled grain percentage and grain is 1000. That appears to reduce the performance of treatment discontinuation in the middle one-third more affected seed weight in 1000 is located. In conclusion, this study revealed that damage to leaves at the flowering stage of sunflower, in particular, leaves from the top or the middle of the plant due to biotic and abiotic factors decreased seed and oil yield.
