Effect of different nitrogen nutrition and soil water potential on physiological parameters and yield of hybrid rice

Super hybrid rice “Liangyou Peijiu” was used as experimental material to study the effect of different nitrogen nutrition and soil water potential on physiological characteristics, yield and agronomic efficiency of nitrogen. The results showed that: 1)Dry weight of shoot and total dry weight of plant increased as nitrogen levels increased at the same soil water potential, but root-shoot ratio was the opposite. 2) Net photosynthetic rate, chlorophyll a, b and total content, leaf SPAD readings and leaf water potential decreased as soil water stress strengthened at the same nitrogen level, while chlorophyll a/b, MDA content and activities of peroxidase were enhanced. Chlorophyll a, b and total content, leaf SPAD readings increased with nitrogen level at the same soil water potential, but leaf water potential and MDA content decreased. 3) Yield decreased with soil water potential at the same nitrogen level. When soil water potential was medium, yield was HN NNLN, while yield was NNHNLN under the conditions of well-watered soil or severe soil drought. Nitrogen agronomy efficiency of rice under NN and HN conditions decreased with soil water stress. The result indicated that rice yield increased significantly at 225 kg/hm2 and 0 kPa soil water potential, and there was negative effect on grain yield and nitrogen agronomy efficiency under excessive nitrogen conditions.