Study on Hyperspectral Diagnosis of Nitrogen Nutrition Index among Different Cotton Varieties under Drip Irrigation

[Objective] To explore the feasibility of rapid and accurate diagnosis of nitrogen nutrition index investigeted nitrogen nutrition index and hyperspectral index in different varieties of drip irrigation cotton. [Method] Five cotton varieties with different characters were selected as the research object under different fertilization conditions, the correlation between nitrogen nutrient index and 17 spectral indices was explored. Then the diagnosis model of nitrogen nutrition was established and verified. [Results] The difference of nitrogen nutrition index among different cotton varieties of drip-irrigation was significant, the hybrid cotton could approach the best condition of nitrogen nutrition level more quickly. In the multiple regression model of nitrogen nutrition index based on hyperspectral analysis, Lumianyan 24 had the highest R², which reached the high level of 0.8. The precision of the model established by Lumianyan 24 was the highest under two years' data verification. [Conclusion] The hyperspectral monitoring model based on nitrogen nutrition index can be used to monitor nitrogen nutrient status of plant. The results of this experiment can provide theoretical basis for precision fertilization in later stage agriculture.