Evaluation of the Effect of Current Assimilation on Aerobic Rice Grain Yield under Different Irrigation Intervals in Northern Region of Khuzestan

This study aimed at establishing the effect of different irrigation intervals on current assimilation and yield of rice genotypes. This research was conducted in Khuzestan Province for two years (2014 and 2015) using four irrigation intervals (1, 3, 5, and 7 days) in the main plots and 12 rice genotypes in the sub-plots, with three replications. The combined analysis results showed that the main levels of irrigation interval, genotypes, and their interaction effect had a significant (P< .01) effect on all attributes. The amount and contribution of current assimilation of the three-day interval with an average yield of 4586.9 kg per hectare and 89.3 percent share had the highest relative value. Moreover, considering the highly positive correlation of grain yield with amount and contribution of current assimilation that were, respectively, (R=0.9**) and (R= 0.5**), we could conclude that the main reason for the increase in rice grain yield in this irrigation treatment was due to the increase in current assimilation – related attributes and allocation of more photosynthesis products to the main plant source. Consequently, IR 81025-B-327-3 genotype in the 3-day interval, which had the highest current assimilation, had relatively high share and efficiency of current assimilation and the highest grain yield with the average of 6555.1 kg per hectare. In general, the increased yield of rice genotypes with greater resistance to drought, especially regarding the three-day interval, can be attributed to the ability of leaf source to increase the considered attributes and the high volume of the tank in fully receiving the assimilated matter produced by processes connected to attributes associated with these properties.