Ammonium enhances the tolerance of rice seedlings (Oryza sativa L.) to drought condition

In order to study the effects of different nitrogen (N) forms on drought tolerance of rice seedlings, both hydroponic and pot experiments were conducted in green house. In hydroponic experiments, water stress was simulated by treatment with polyethylene glycol (PEG, 10% in w/v, MW6000); in pot experiments, rice seedlings were cultivated under non-flooded conditions. The results showed that: (1) under water stress conditions, the decrease in plant growth and photosynthesis under ammonium supply was less than under nitrate supply; (2) under non-flooded cultivation, the biomass and photosynthesis in rice plants supplied with ammonium and ammonium + dicyandiamide (DCD, a nitrification inhibitor) were higher than those in nitrate fertilization; (3) in hydroponic experiments, water uptake of rice seedlings under ammonium nutrition was higher than under nitrate nutrition. It is concluded that, ammonium nutrition can enhance the tolerance of rice plants to water stress.