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【目的】对不同株型小麦冠层叶片垂直分布的方向光谱响应进行研究,探索精确描述小麦冠层空间信息的途径,为农田作物快速、无损的光谱监测提供新的理论与技术。【方法】以2个株型不同的小麦品种为材料,采用自下向上分层切片方法,分析冠层不同部位叶片对冠层方向光谱的影响。【结果】去除不同叶位叶片后,小麦冠层光谱在300～700,800～1300,1400～1800nm波段差别明显;不同观测角度中,与传统90°视角获得反射信息比较,30°和60°视角反射光谱包含较多下部叶片信息,下部叶片对冠层光谱反射率贡献较大,0°视角反射光谱包含较多上部叶片信息,上部叶片对冠层光谱反射率贡献较大;小麦冠层的穗层和倒1叶对方向光谱产生很大影响。不同的2个小麦品种,ZY9844上部叶片对反射率的影响比P7弱。【结论】小麦冠层不同部位叶片,对冠层方向光谱影响不同,根据冠层特点,通过改变光谱观测角度,可以提高作物冠层光谱监测的精度。
【Objective】 The aim of this study is to study the vertical and directional spectral response of canopy leaves in different plant types and to explore ways to accurately describe wheat canopy spatial information so as to provide new theories and techniques for fast and nondestructive spectral monitoring of farm crops. 【Method】 Two wheat cultivars with different plant types were used as materials to analyze the influence of leaves in different parts of the canopy on the canopy orientation with a slice-by-slice method. 【Result】 The results showed that the canopy spectra of wheat differed significantly between 300 ~ 700, 800 ~ 1300 and 1400 ~ 1800 nm after removing leaves with different leaf positions. Compared with the traditional 90 ° angle of view, the reflectance at 30 ° and 60 ° The spectra contained more information of the lower leaves. The lower leaves contributed more to the spectral reflectance of the canopy. The reflectance spectra at 0 ° included more information of the upper leaves, and the upper leaves contributed more to the spectral reflectance of the canopy. And inverted 1 leaves have a significant effect on the direction of the spectrum. Different two wheat varieties, ZY9844 upper leaves on the reflectivity than P7 weaker. 【Conclusion】 The effects of different parts of canopy on the canopy spectral directions are different. According to the characteristics of canopy, the precision of crop canopy spectral monitoring can be improved by changing the spectral observation angle.