基于Greenseeker光谱法的棉花氮素营养诊断研究

Study on diagnosing nitrogen status of cotton using Greenseeker

利用主动遥感光谱仪(Greenseeker)对新疆2个主栽棉花品种4个施氮量条件下2年生育期间的冠层归一化植被指数(NDVI)值进行测试,研究不同施氮量对棉花冠层NDVI值、植株氮素积累速率和叶片全氮含量的影响以及田间条件下简便、快速、非接触性的作物氮素营养状况诊断方法。结果表明:在棉花生育期内,冠层NDVI值呈单峰曲线变化,峰值出现在出苗后90d左右,以后逐渐降低;NDVI值和棉株氮素积累速率呈正相关关系,决定系数R^2在盛花期达到最大,为0.844.7;NDVI值变化趋势与叶片全氮含量呈正相关,决定系数R^2在盛花期达到0.7980。棉花冠层NDVI值随着施氮量增加而提高,不同氮素处理间NDVI值在盛花期和花铃期达极显著差异;主动遥感光谱仪在棉花生长的盛花期和花铃期可以预测棉花氮素养分状况。

Field experiments were carried out on two cultivars of cotton at different growth stages under different nitrogen levels using portable active remote sensing spectrometer Greenseeker to study the effects of different nitrogen application rate on cotton canopy NDVI, nitrogen accumulation rate and leaf nitrogen content. Diagnostic methods for crop nitrogen nutritional status which was simple, rapid, noncontact under field conditions were also studied. The result indicated that canopy NDVI showed in a single peak curve change at cotton growth stage, and peaked at around 90 days after emergence and then gradually reduced. Canopy NDVI increased with increasing nitrogen fertilizer in proper range of nitrogen level, but when nitrogen level was higher than N2, the NDVI was not affected significantly with the increasing of nitrogen level. NDVI was positively correlated with nitrogen accumulate rate and leaf nitrogen contents. The coefficients of determination for the stepwise regression were 0.844 7 and 0.798 0 during flowering stage. Greenseeker provides an effective means for diagnosis of nitrogen in cotton.