Effects of different Nitrogen forms and osmotic stress on water use efficiency of rice (Oryza sativa)

A hydroponic experiment with simulated water stress induced by polyethylene glycol (PEG) was conducted in greenhouse to study the effects of different nitrogen (N) forms (; and the mixture of and ) on water stress tolerance and water use efficiency (WUE and WUE_T) of different rice cultivars. Two rice cultivars (cv. ‘Shanyou 63’ hybrid indica and ‘Yangdao 6’ indica, China) were grown under non‐water‐ or water‐stressed condition 10% (w/v) PEG, molecular weight 6000] with different N forms for 3 weeks. Under non‐water stress, the biomass of Shanyou 63 was 50.0% and 64.3% and of Yangdao 6 was 6.9% and 87.8% higher under the supply of mixture of and than either under the sole supply of or , respectively; under water stress, the biomass of both rice cultivars decreased in all three nitrogen forms compared with non‐water stress; however, the inhibitory effect of water stress on biomass varied between and nutrition; the reduction of dry matter was significantly higher in than in nutrition. Compared with non‐water stress, under water stressed condition, WUE of both two rice cultivars significantly decreased in supply; WUE did not vary in and the mixture supply. It is concluded that (a) the resistance of water stress of rice seedlings is related to nitrogen form; (b) under water stress, could maintain a higher WUE compared with ; (c) hybrid indica rice seedlings have a higher water stress tolerance than indica rice seedlings.