数字图像诊断技术在冬小麦氮素营养诊断中的应用

本文应用数码相机获取冬小麦冠层图像并对其进行相应色彩参数处理, 结合土壤、植株快速测试技术, 分析了色彩参数与传统氮素营养参数之间的数量关系, 研究了应用数字图像技术进行冬小麦氮素营养诊断的可行性, 建立了应用数字图像技术诊断冬小麦氮素营养状况的图像获取方法, 筛选出了适宜于冬小麦氮素营养诊断的最佳色彩参数以及最佳诊断时期, 建立了冬小麦氮素营养诊断指标体系和推荐施肥方程。研究结果表明, 数字图像技术可以作为冬小麦氮素营养诊断的方法。数字图像获取时, 可将数码相机与冬小麦冠层呈30°~60°角度进行拍摄。在冬小麦拔节期和孕穗期多数冠层图像色彩参数与施氮量、叶片SPAD 值、植株硝酸盐浓度、植株全氮含量、0~90 cm 土壤硝态氮含量之间存在显著或极显著相关关系; 在众多色彩参数中, 拔节期冠层图像绿光标准化值G/(R+G+B)与各项氮素指标的相关性最好, 可作为冬小麦氮素营养诊断的最佳色彩参数指标；拔节期可作为应用数字图像技术进行氮素诊断的关键时期。

Diagnosis of the state of N in wheat via digital image processing technique

This study used digital image acquisition via digital camera and analysis method in combination with rapid soil and plant N test to diagnose the state of N in wheat crops and recommend N fertilization modes in wheat fields. The relationship between color parameters and N nutrient indices was analyzed and the possibility of using digital image analysis method to diagnose the state of plant N evaluated. Then a standard method for digital image acquisition and application in plant N diagnosis was established. The best mode for diagnosing the state of plant N via digital image analysis method was also determined. The study further established a N diagnosis index system and an equation for recommending N application. The result indicated that digital image processing technique was usable in detecting the N state in winter wheat. The best angle between digital camera and wheat canopy in the field was 30°~60°. Significant correlations were noted among color parameters and N application rate, SPAD, plant nitrate content, plant total N content and nitrate contents in the 0~90 cm soil depth at wheat jointing and booting stages. Compared with other plant canopy color parameters, normalized greenness intensity (NGI), calculated as G/(R+G+B), was much better as it produced better correlations with plant total N, SPAD, nitrate content and soil nitrate content at jointing stage. While NGI was the best diagnosis index, jointing was the key diagnosis stage of the state of N in winter wheat crops.