Effects of the irrigation regimes on the physical grain characters of aerobic rice (Oryza sativa L.) genotypes in Khouzestan province

Background and objectives Rice can be irrigated like wheat and corn as an aerobic plant (1). There is a negative relation between the grain yield and quality, has various indexes in the world like Iran where the rice with long and separate seeds is preferred (2). The important factors of reducing the rice quality are increasing immature seeds, cracks on the surface, narrow and thin seeds (3). With regard to water crisis, it’s essential to increase knowledge level and awareness about water tension loss effects on qualitative and quantitative traits of seeds. This study aims at realization of this purpose and reducing the negative effects of water tension. Materials and methods An experiment was carried out to study of irrigation regimes on rice genotypes grain milling quality (Total rice recovery, degree of milling, but hull, brane, head rice, broken rice, grain width, grain length, grain length after cook and grain yield) of Khuzestan province in a split-plot arrangement using randomized complete blokes comlete bloks design with three replications in two cropping seasons (2014 and 2015) at Shavoor Agricultural Research Station, Dependent in Research Center of Agricultural and Natural Resources of Khuzestan. For exposing rice genotypes to four different irrigation regimes (1, 3, 5 and 7 days), and 12 genotypes were randomized in sub-plots. The variance and correlation analysis were carried out by using the SAS and SPSS software after ensuring the normality of the data and the mean of the data was compared to a through the Tuke test. Results and discussion The results of combined analysis of variances showed that the apart from the percentage bran and grain width that represents of them the sum was a significant different in irrigation regimes by genotypes interaction in all of trades. On the other hand, the related irrigation regimes, genotypes had different reaction. Such that past of the grain width and length decreased with increasing stress, because of adaptability genotypes and more favorable moisture, the highest of grain yield, total milled rice recovery, degree of milling, and head rice were in second irrigation regimes. But hull, bran and broken rice percentage had the lowest amount. Whereas there were a significantly positive and negative correlation between these traits and grain yield. Conclusion Totally, the results of present study showed that traits of seed quality and quantity in the second irrigation regime has the most suitable reactions in terms of reducing crust and bran as well as increasing desirable traits like efficiency conversion degree and rice. And also, they showed the role of irrigation management with regard to genotype diversity. These results indicated that the seed yield and desirable trait in the thirds irrigation with five-day irrigation have no significant relation with flooding irrigation. It can be used as a suitable method and approach to increase irrigation efficiency of aerobic rice genotypes.