冬小麦冠层光谱与土壤供氮状况相关性研究

Correlation between Soil Nitrogen Situation and Canopy Spectra of Winter Wheat

通过设置2个冬小麦品种不同氮素水平的完全随机区组试验,获取冬小麦关键生育期(返青期、拔节期、孕穗期、灌浆期)的土壤氮素、植株氮素和冠层光谱数据,通过分析土壤氮素与植株氮素间的相关关系,间接构建土壤氮素状况的光谱诊断模型。结果表明,不同施氮水平冬小麦各生育期冠层光谱与麦田土壤氮素含量差异显著,土壤硝态氮、碱解氮含量与冬小麦植株氮素含量的相关系数达到0.72以上,相关系数分别在0.72~0.84和0.75~0.82之间,均达极显著水平,而土壤全氮含量与冬小麦植株含氮量的相关性相对较差;研究证实土壤调节植被指数SAVI(1040,680)和比值植被指数RVI(1040,680)分别与土壤硝态氮、碱解氮含量具有重要的关系。另外,基于光谱参数SAVI(1040,680)的土壤硝态氮估算模型(R^2≥0.739 6)和基于RVI(1040,680)所构建的碱解氮含量估算模型(R^2≥0.810 0)具有较好的估测能力,可以实现利用冠层光谱对土壤氮素状况的实时、快速估测。

Soil nitrogen is important to crop production. The lower nitrogen efficiency is mainly caused by the reason that the nitrogen is commonly applied untimely or non-appropriately. In order to take advantage of winter wheat canopy spectra synchronous implementation indirectly and rapidly diagnose soil nitrogen status,experiment with completely randomized block was conducted for two wheat varieties with different nitrogen levels. Soil and plant nitrogen levels and real-time canopy spectra were measured at different growth stages of winter wheat, i. e., the reviving, jointing, booting and filling stages.Mathematical statistical methods were used to analyze the quantitative relationship between soil nitrogen and plant nitrogen,and build a remote monitoring model of soil nitrogen by using the canopy spectral reflectance. The results showed that the canopy spectral reflectance of winter wheat at each growth stage was significantly different from soil nitrogen content with the application of different levels of nitrogen fertilizer. There were significant relationship between soil nitrate nitrogen content,soil available nitrogen content and nitrogen content of winter wheat plants,and the correlation coefficient could exceed 0. 72.However,the relationship between soil total nitrogen content and nitrogen content of winter wheat plants was hardly relevant. The spectra parameters of SAVI（ 1040,680） and RVI（ 1040,680） were determined to have important relationship with the soil nitrate nitrogen and available nitrogen contents,respectively.Moreover,the monitoring models of soil nitrate nitrogen and available nitrogen contents based on the spectra parameters performed the best with R^2≥0. 739 6 and R^2≥0. 810 0,respectively. The research result would supply some technical reference for the real-time monitor of soil nitrogen in winter wheat fields by using the canopy spectral reflectance.