不同穗型常规籼稻品种氮素吸收利用的基本特点

在群体水培条件下，以国内、外不同年代育成的常规籼稻代表品种(2001年为88个、2002年为122个)为材料，测定干物质重(包括根系)、产量及其构成因素、氮素含量等，采用组内最小平方和的动态聚类方法将供试品种按单穗重从低到高依次分为A、B、C、D、E、F 6类，研究各类品种氮素吸收利用的基本特点。结果表明，(1)供试品种单穗重差异较大，适当增加穗重有利于水稻品种产量的提高；(2)不同穗型水稻品种植株含氮率差异较小，大穗型水稻品种抽穗期、结实期、成熟期群体氮素累积量和个体(单穗)氮素累积量均显著大于小穗型品种，个体(单穗)吸氮量特别是抽穗前单穗吸氮量大，是大穗型品种主要生育阶段群体氮素累积量显著大于小穗型品种的重要因素；(3)中等偏大穗型的水稻品种氮素收获指数、氮素籽粒生产效率较高；(4)大穗型水稻品种播种到抽穗天数、全生育期天数较长；(5)氮素累积量、氮素籽粒生产效率均是影响穗重的重要因素，但氮素累积量作用较大；(6)吸氮强度尤其是个体(单穗)吸氮强度是不同穗型水稻品种群体与个体(单穗)氮素累积量差异的主要因素。

General Characteristics of Nitrogen Uptake and Utilization in Conventional Indica Rice Cultivars with Different Panicle Weight Types

A total of 88 and 122 conventional indica rice (Oryza sativa L.) cultivars with different types of panicle weight (PW) were solution-cultured in 2001 and 2002, respectively. On the basis of PW, these cultivars were classified into 6 types from low to high (i.e. A, B, C, D, E, and F, A was the lowest, F was the highest). Dry matter weight and nitrogen content of roots, culm and sheath, leaf, and panicle were measured at heading and maturity stages, and the grain yield and its components were tested after harvest. No significant difference in nitrogen content of the plant was detected between various PW types of conventional indica rice. The population nitrogen accumulation (NA) and individual NA at heading, grain filling and maturity stages were higher in cultivars with large PW than in cultivars with small PW. The effects of individual NA and panicles per area on population NA were both significant, especially the individual NA at heading stage. In cultivars with medium to large PW, nitrogen harvest index and nitrogen use efficiency for grain yield (NUEg) were higher than those in other rice types. And rice cultivars with large PW showed longer growth duration especially days from sowing to heading. The effects of NA and NUEg on PW were both signifi-cant, while the NA was more effective. The N uptake intensity of population especially N uptake intensity of individual was the main factor influencing N accumulation levels of population and individual in conventional indica rice cultivars.