Effect of planting time on flag leaf anatomy and grain yield of rice genotypes in Khuzestan province

To study the effect of planting time on the flag leaf anatomy (stomata number, stomata diameter and surface, large and small vascular bundles surface, xylem, and phloem) of rice genotypes in Khuzestan climate a field experiment was conducted as split plot arrangements in randomized complete blocks design with three replications, in Shavoor agricultural research station 70 km north of Ahvaz, Iran, in 2010-2011. The main plots was planting time in three levels (15 March, 14 April and 26 May 2011) and the sub-plots comprised of rice genotypes; Gerde Zanjan and 3 local genotypes namely Hoveizeh, Hamar, and Gerde Ramhormoz (tolerant to heat), 4 foreign genotyes (Dollar, N22, CR547-1-2-3 and IR1567-228-3-3) and two breeding lines; No. 7 and 13. Results revealed that, for all the evaluated traits, there was a significant effect of planting time, genotype and the interaction of genotype × planting time. Hamar genotype in 26 May and IR1567-228-3-3 in 15 March had the highest and least numbers of stomata with averages of 1366 and 786, respectively. Maximum and minimum stomata diameter and surface were observed for genotype N22 in 26 May (diameter 30.3 μm and surface 484.5 μm²) and Gerde Ramhormoz in 14 April (diameter 13.6 μm and surface 97.7 μm²), respectively. The highest large vascular bundles surface was recorded for line No. 13 in second planting time with average of 1348.5 μm² and the lowest large vascular bundles surface belonged to Dollar with average of 5267.6 μm² in 26 May planting time. Maximum and minimum small vascular bundles surface belonged to Hoveizeh in 15 March with average of 2011.5 μm² and Dollar in 14 April with average of 321.2 μm², respectively. IR1567-228-3-3 (2089.7 kg.ha-1) in had the highest grain yield in 15 March and Hoveizeh (4898.1 kg.ha-1) in 14 April and Hamar genotypes (4804.4 kg.ha-1) in 26 May planting times had the highest grain yields.