Effects of watering regime and nitrogen application rate on the photosynthetic parameters, physiological characteristics, and agronomic traits of rice
,?2017,39(6)135.
10.1007/s11738-017-2432-7
Abstract
Water and nitrogen (N) are two of the most important abiotic factors limiting rice yield. However, a little information is available on why a moderate water and N interaction significantly increase rice biomass, from the point of view of photosynthetic physiology. A pot experiment with three water regimes [continued flood (CF), alternate wetting and moderate drying (WMD), and alternate wetting and severe drying (WSD)] and four N application levels (no nitrogen, N0; 90 kg hm?2, N1; 180 kg hm?2, N2; 270 kg hm?2, N3) was carried out to investigate this problem. Results demonstrated that WSD significantly inhibited rice height, leaf area, chlorophyll content, photosynthesis, and yield at the four different N levels, as compared to that with CF and WMD. However, WMD substantially alleviated these reductions, and their values were not significantly different from those of CF. Contents of leaf soluble protein and total chlorophyll in WMD were increased compared to the WSD, and this mitigating effect was beneficial to the increase of rice photosynthesis and yield development. Photosynthesis in rice leaf was significantly affected by water status but not N level. Analysis of variance demonstrated a significant effect of water on spikelet number, which indicates that the reduction of spikelet number under water stress may be the major reason for its low yield. Therefore, we concluded that WMD could be considered as an effective water management regime to obtain high yield in rice production, and its strengthened drought tolerance was closely associated with the higher dry matter and in the physiological characteristics including an increase in spikelet number, chlorophyll and soluble protein contents, and photosynthetic rate.