叶绿素仪在棉花氮肥推荐中的研究进展

叶绿素仪(SPAD-502)在监测棉花氮素营养水平和及时提供追肥所需的信息方面有快速、简便、无损的特点，但其精度受到各种因素的影响，总结了不同棉花品种上部叶片的叶绿素SPAD值全生育期变化规律以及叶位、样本量、施氮施磷水平等因素对其精度的影响。提出了通过量化SPAD读数与植株氮含量及衰老程度的关系，明确不同生育时期正常营养状态下的SPAD读数临界值，可提高棉花氮素营养诊断精度。最后进一步提出了运用叶绿素仪进行棉花氮素营养诊断尚需解决的几个问题。

A Review on Chlorophyll Meter Application on Nitrogen Fertilizer Recommendation for Cotton

SPAD-502 meter provided a simple, fast and nondestructive method to monitor cotton nitrogen status and predicted the need for fertilizer-N topdressing on time, but its precision was influenced by many factors. Because SPAD-502 meter diagnosed the nitrogen nutrient status indirectly by means of measuring color of leaves(value of SPAD), it was important to understand factors that affected SPAD readings in order to improve its application effect. In this paper, the dynamic rules of chlorophyll contents of upper leaves of cotton plants were set forth and factors which influenced SPAD readings, such as cotton variety, development stage, the leaf position, the sample number of leaves and different nitrogen and phosphorus fertilizer rates were studied. The research progress on improving the precision of cotton nitrogen diagnosis by quantifying the relationship of SPAD reading of nitrogen content and the degree of aging, as well as nitrogen recommendation by quantifying the relationship of SPAD reading and topdressing were also reviewed. For a purpose of further improving the precision of nitrogen status diagnosis by SPAD-502 meter and fertilizer recommendation, few questions need to be settled was put forward at last.