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叶色是氮素营养诊断最常用的指标,获得准确的叶色诊断指标是水稻精确定量施氮的基础。叶色诊断指标实际上就是稻谷产量最高时的最适叶色。已有报告指出,叶色诊断指标受到群体大小和结实期光照条件的影响。研究的目的是,找出叶色诊断指标随群体大小和光照条件而变化的规律,为精确定量施氮提供理论和技术依据。2004—2005年早季和晚季,在广州以两系杂交稻粤杂122为试材,设置8种不同氮肥处理,进行2年4季田间试验,抽穗期测定叶色(SPAD)和叶面积指数(LAI),成熟期测产。结果表明:(1)不同季节的最适叶色存在明显差异,4季变动于39～45之间。根据产量与叶色的定量关系,可以准确、快速地确定特定条件下的叶色诊断指标。(2)稻谷产量与抽穗期群体指数(SPAD与LAI的乘积)呈开口向下的抛物线关系。抽穗期SPAD、LAI和结实期日照时数,可以解释不同年度、季节和不同氮肥处理的稻谷产量变异的86%。最适群体指数随着结实期日照时数的增加而提高。(3)最适叶色随着日照时数的增加而提高,随着LAI的增加而降低,3者之间存在显著的定量关系。应用这一关系,可根据结实期光照条件,估计出异地异季的叶色诊断指标。
Leaf color is the most commonly used indicator of nitrogen nutrition diagnosis. Obtaining accurate leaf color diagnostic index is the basis of precise and quantitative nitrogen application. The leaf color diagnostic index is actually the most suitable leaf color when the rice yield is the highest. It has been reported that the leaf color index is influenced by the size of the population and the light conditions during the fruiting period. The purpose of this study is to find out the regularity that the diagnostic index of leaf color changes with population size and light conditions, and provide theoretical and technical basis for precise quantitative N application. 2004-2005 early and late seasons, two-line hybrid rice Yueza 122 was used as experimental materials in Guangzhou. Eight different nitrogen fertilizers treatments were set up. Field experiments were conducted in two years and four seasons. The leaf color (SPAD) and leaf area Index (LAI), mature production test. The results showed that: (1) There was a significant difference in the optimum leaf color in different seasons, and the change in 4 seasons was between 39 and 45. According to the quantitative relationship between yield and leaf color, it can accurately and quickly determine the leaf color diagnostic index under certain conditions. (2) The rice yield and heading date group index (the product of SPAD and LAI) is parabolic downward. The SPAD, LAI at heading and the number of sunshine duration at the setting stage can explain 86% of the variation of paddy yield in different years, seasons and different nitrogenous fertilizers. The optimum community index increased with the increase of sunshine hours in the seed setting stage. (3) The optimum leaf color increased with the increase of sunshine hours and decreased with the increase of LAI. There was a significant quantitative relationship among the three. Application of this relationship, according to the light conditions of the staging period, to estimate off-season leaf color diagnostic indicators.