为了探讨水稻冠层光谱对叶片叶绿素含量的响应规律,以双季早稻为材料,设置不同施氮量处理的田间试验,测定水稻冠层光谱和叶片叶绿素含量,计算基于冠层反射光谱的特征变量,研究水稻冠层高光谱特征变量与叶片叶绿素含量之间的关系。结果表明：施用氮肥对反射光谱有明显的影响,在可见光范围内,不施氮处理的反射率高于施氮处理,尤其在波长550 nm左右的绿峰处显著增加,在近红外区反射率随施氮量的增加而增加;与叶绿素含量相关性较好的光谱位置参数是红边位置和红谷反射率,随着叶绿素含量的增加,红谷反射率降低,红边位置向长波方向移动;比值植被指数R800/R550、R750/R553和R990/R553,以及色素比值指数PSSRa、PSSRb与chla、chlb、chl(a+b)呈极显著正相关,可以作为水稻冠层叶片叶绿素监测的特征变量。

The aim of this paper is to explore the response regularity of canopy spectral on chlorophyll content for rice. Field trials of different nitrogen application processing are set using double-season early rice as materials. Rice canopy spectrum and chlorophyll content of leaves were measured. The characteristic variables were calculated based on canopy reflectance spectral. The relationship between rice canopy hyperspectral characteristic variables and chlorophyll content was studied. The results showed that applying nitrogen fertilizer had a significant effect on canopy reflectance spectral. The reflectance of rice without applying nitrogen fertilizer was greater than ones with nitrogen fertilizer in visible light,especially at green peak region where the wavelength was around 550 nm. The reflectance in near infrared region increased with the nitrogen fertilizer application. The characteristic variables based on spectral position such as red edge position and reflectance in red valley region presented a great correlation with chlorophyll content. Reflectance in red valley region Octreases and red edge moves to longer wavelengths with the increase of chlorophyll content. The ratio vegetation indices R800 / R550,R750 / R553 and R990/R553,the pigment specific simple ratio PSSRa,PSSRb and chla,chlb,chl (a+b) showed a significant positive correlation in the two varieties ,which can be used as characteristic variables in rice canopy chlorophyll monitoring.