Evaluation Anatomy of Flag Leaf of Rice Cultivars Affected Different Planting Dates under Dry and Warm Climate condition in Southwest of Iran

Current research was conducted during 2006 and 2007 cropping seasons to assessment the anatomy of the flag leaf and yield of rice in the Khuzestan province according split plot experiment based on randomized complete block design with three replications. Main plot included different sowing dates at three levels (5 May, 26 May and 16 June). Hoveizeh, Hamar (Heat tolerance), Ghermez Anbori, Champa (Heat sensitive) and Danial (Relatively heat tolerant) cultivars at five levels were belonged to sub-plots. The results of combined analyses showed that was a significant different in planting date by variety interaction in all of trades. On the other hand, the related temperature condition, varieties had different reaction. Given that metabolic energy is needed to transfer sugar in this path, reduction of phloem cell surface can predispose the material preservation and shortening the transfer path by reducing the rate of respiration and transfer intervals. In the other hand, size of phloem depends on the size of source and reservoir and their relationships. Highest and lowest levels of large vascular bundles were related to 2nd and 1st planting dates; but highest and lowest levels of small vascular bundles, xylem and phloem obtained in 2nd and 1st planting dates respectively.