| The field experiment was carried out using 34 Medium-Maturing Medium Japonica Rice varieties,adopted in Huaibei area,with seven nitrogen application levels(0,150.0,187.5,225.0,262.5,300.0,337.5 kg ha-1)to investigate the differences of the nitrogen absorption and utilization.We defined the highest rice yields under different nitrogen levels as the highest population productivity of N fertilization.Then according to highest population productivity of N fertilization,rice varieties could be classified into four types including top type(TT),high type(HT),middle type(MT)and low type(LT).On this basis,the yield components,group photosynthetic material production and N absorption and utilization of the four types rice varieties were studied.The main results were as follows:(1)Optimum N levels of tested varieties which were corresponding to their highest population productivity of N fertilization converged in the range of 225.0-300.0 kg ha-1,while the highest grain yields were significant differences.With increasing productivity level,panicles per unit area increases firstly and then decreases,spikelets per panicle and the total spikelet number increases and the seed-setting rate declines.With increasing productivity level,Percentage of productive tillers,leaf area index,photosynthetic potential,ratio of leaf area of productive tillers,ratio of leaf area from flag leaf to 3rd leaf,grain-leaf ratio and total accumulation were increased.From translating to jointing stage,the ratio of nitrogen accumulation among the 4 productivity levels were as follows:LT>MT>HT>TT.(2)TT'N concentration of aboveground,steam-sheath and leaf in different levels was higher than the other 3 levels.Jointing to heading stage and heading to maturity stage,the order is:TT>HT>MT>LT.N uptake rate of the top type is fastest,low type is slowest and 36.59%,34.36%,51.85%higher in translating to jointing,Jointing to heading and heading to maturity growing stages.N translocation of and leaf was higher than steam-sheath.N translocation of steam-sheath and leaf,N translocation of leaf,increase in N of panicle,N use efficiency,and N requirement for 100 kg grain were all increased with increasing productivity level,N translocation of steam-sheath and N translocation conversion rate of vegetative organ were all decreased.According to the N use efficiency,34 varieties were divided into Low ANRE(apparent nitrogen recovery efficiency),Middle ANRE,Comparative High ANRE and High ANRE.Wuyunjing 27,Zhongdao 1,Ningjing 4 and Lianjing 7 belonged to high yield and high ANRE varieties.(3)K concentration of aboveground parts of plant steam-sheath and leaf in different types was the highest at heading stage and that was higher in TT than the other three types.K concentration of panicle was no significant difference among tested varieties.With increasing productivity level,total K accumulation increased.From transplanting to jointing stage,the K accumulation in LT was 120.56 kg ha-1 accounting for 50.56%.The K accumulation of TT was 108.02 kg ha-1,accounting for 35.99%.After jointing,the K accumulation and ratio at each growth stage of TT were higher than those of other three types.The K uptake rate showed a trend of MT>LT>HT>TT from transplanting to jointing stage,and TT>HT>MT>LT from jointing to heading stage and from heading to maturity stage.K translocation and K translocation efficiency of leaf were obviously higher than those of steam-sheath.K translocation of TT and HT's K translocation efficiency were both the highest.The increasing in K of panicle increased with increasing productivity level.From heading to maturity stage,K translocation conversion rate of vegetative organ was the highest in LT,medium in MT,and the lowest in TT.Internal nutrient efficiency and K requirement for 100 kg grain among four types were no obvious difference and K partial factor productivity and harvest index of K showed a trend of TT>HT>MT>LT. |
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