小麦冠层反射光谱与植株水分状况的关系

研究了不同土壤水、氮条件下小麦冠层光谱反射特征与叶片和植株水分状况的相关性．结果表明，在小麦主要生育期，冠层叶片含水率与460～510、610～680和1480～1500nm波段范围内的光谱反射率有较高的相关性，植株含水率与810～870nm波段范围内的光谱反射率密切相关．在整个生长期内，小麦冠层叶片含水率与460～1500nm波段范围内的光谱反射率均有良好相关性，植株含水率与560～1480nm波段范围内光谱反射率的相关性均达到极显著水平．冠层叶片(CL)、上层叶(UL)和下层叶片(LL)含水率与光谱指数的相关程度为CL>LL>UL．冠层叶片和植株含水率与比值指(R(610，560))和光谱指数(R(610，560)／ND(810，610))呈极显著线性负相关，与归一化指数((R810-R610)／(R810+R610))呈极显著线性正相关．其中，用光谱指数(R(610，560)／ND(810，610))监测不同生育期小麦冠层叶片和植株含水率的效果最好。

Relationship between canopy reflectance and plant water status of wheat

The study on the relationship between canopy reflectance characteristics and plant water status of wheat under different soil water and nitrogen levels showed that the water contents of canopy leaf and plant had a significant correlation with the spectral reflectance of 460-510, 610-680, 1480-1500 and 810-870 nm bands at different growth stages and that of 460-1500 and 560-1480 nm bands over the whole growth period. The correlation degrees of canopy leaf (CL), upper-layer leaf (UL) and lower-layer leaf (LL) water content with spectral index were in the order of CL>LL>UL. In addition, the water contents of canopy leaf and plant after jointing stage were negatively linearly related to the ratio index R(610, 560) and spectral index (R(610, 560)/ND(810, 610)), but positively correlated with the normalized difference index ((R810 - R610)/(R810 + R610)), indicating that spectral index (R(610, 560)/ND(810, 610)) could be a good indicator for monitoring water status in wheat plant.