利用叶绿素计对短季棉氮素营养诊断的初步研究

A Preliminary Study on Nitrogen Nutrition Diagnosis for Short-Season Cotton with a Chlorophyll Meter

研究了以叶绿素计诊断短季棉的氮素营养。结果表明,不同生育时期功能叶叶绿素计读数与叶绿素含量、全氮含量（N_a、N_(dw)）及施氮水平呈极显著线性正相关,其中对N_a的正相关高于N_(dw);与光合强度呈极显著指数相关;与产量、三桃数呈极显著二次曲线回归。获得了不同生育时期叶绿素计诊断指标。叶绿素计变动1格的参考施氮量为23.3～25.0kgN/hm^2,可作为高产低耗施肥的配套技术之一。

A two-site experiments for five to six nitrogen levels was carried out to study the relationship between chlorophyll meter readings (SPAD value) and physiological and yield traits in short-season cotton. The result showed that there are significant linear correlations between SPAD value and both contents of nitrogen and chlorophyll at each growth stage, and the correlation of SPAD value to nitrogen concentration on a leaf area(Na) was closer than that on a dry weight(Ndw). This implies Na can be predict better from SPAD. On the other hand, significant curvilinear correlation was found between SPAD value and photosynthesis intensity, lint yield and total boll number per hectare, respectively. Furthermore, a strong linear regression existed in SPAD value to N fertilizer level, and the regression coefficients were near(0. 04~0. 043)before boll opening stage in the two different sites. This suggested that the chlorophyll meter can be used to determine the requirement of N applications. The optimum SPAD value at different stages and N topdressing amount for regulating SPAD value are also presented.