The Effects of Different Irrigation Regimes and N Fertilizer on Yield, Yield Components and the Content of Micronutrients in Brown and White Rice (cv. Hashemi and Gilaneh)

Due to the limit of water availability in rice fields, alternate wetting and drying irrigation are used instead of continuous submergence to reduce water consumption in rice fields. Therefore, this study was conducted to evaluate the effects of different irrigation regimes and N fertilizer rates on yield, and the content of micronutrients in brown and white rice at Rashat during cropping seasons of 2016-2017 and 2017-2018. Experiment was arranged in split plot based on complete randomized block design with 3 replications in which water regimes continuous submergence (I1), 7 (I2) and 15 (I3) day interval irrigation were asseigned as main factor and nitrogen fertilizer levels (50 (N1), 75 (N2), and 100 (N3) kg.ha-1) as sub factor, and cultivars, Gilanh (C1) and Hashemi (C2) as sub sub factor. Results showed that the effect of year on yield and number of panicle per m2 was significant. The interaction of different irrigation treatments and N fertilizer and cultivar on the number of panicle per m2 in 2017, yield in 2017 and 2018, and micronutrient content were significant. Increasing the irrigation intervals decreased number of panicle per m2, number of seed per panicle, weight of 1000 grain, and yield, while the consumption of 75 and 100 kg.ha-1 of nitrogen fertilizer increased these traits in all three irrigation treatments compared to the level of 50 kg.ha-1 of nitrogen fertilizer. Gilaneh in all irrigation treatments showed higher yield, number of panicle per m2, and number of seed in panicle. Also, increasing of the irrigation intervals increased the content of micronutrients in brown and white rice seeds. The consumption of 75 and 100 kg.ha-1 of nitrogen fertilizer increased these traits as compared to the other levels of nitrogen fertilizers. The highest content of Zn, Cu, Fe, and Mn was observed in brown and white rice at irrigation interval at 14 days and 100 kg.ha-1 nitrogen fertilizer application. The consumption of 100 kg.ha-1 of nitrogen fertilizer increased the quantitative and qualitative grain yield of both cultivars as compared to the other two levels of nitrogen fertilizer and to irrigation regimes. Proper level of fertilizer would compensate the adverse effects of increasing irrigation intervals.