Effects of irrigation regimes on yield and quality of upland rice and paddy rice and their interaction with nitrogen rates

The study of water-nitrogen (N) interaction to improve crop drought resistance and reduce environmental pollution has increasingly become a hot topic. However, the response of yield and quality of paddy rice and upland rice to N nutrition under different irrigation regimes is little known. Continuous flooding cultivation (CF, control) and bare-dry cultivation (BD) were used to cultivate paddy rice cultivar Yangjing 687 (japonica) and upland rice cultivar Zhonghan 3 (japonica), and 3 N application rates, 140 (low N, LN), 210 (normal N, NN) and 280 kg ha−1(high N, HN), were set for each irrigation regime. The results showed that under BD and CF irrigation regimes, the yield of paddy rice was the highest at NN, while that of upland rice was the highest at BD with NN and at CF with HN, breakdown viscosity was the highest and setback viscosity was the lowest for paddy rice at LN and for upland rice at NN. Increasing N application, the chalky kernels percentage and the chalkiness of upland rice increased first and then decreased, while that of paddy rice decreased under BD and increased under CF. Compared with CF, BD made the seed setting percentage and 1000-grain weight of upland rice and paddy rice different, and improved the appearance and nutritional quality of upland rice. The correlation between the cooking and nutritional quality and leaf N content of upland rice was lower than that of paddy rice. These results suggest that the yield and cooking quality of upland rice were high under BD with NN, and the paddy rice yield was high under BD with NN or CF with NN.