棉花苗期冻害高光谱特征研究

Study on Hyperspectral Features of the Frostbite Cotton at Seedling Stage

通过盆栽、霜箱模拟冻害,结果表明:冻害棉苗叶绿素含量、光合、蒸腾速率显著低于对照组。叶绿素含量与高光谱特征相关分析表明对照组高相关波段集中在红、近红外波段,而冻害组集中在蓝、绿、红波段。根据相关系数及高光谱反射率、一阶导数、倒数后对数三类特征值差异显著性分析,反射率、一阶微分不易选取冻害胁迫诊断波段,利用反射率倒数后对数,B696、B720、B768、B845可作为诊断波段。由诊断波段的反射率值计算的植被指数与叶绿素含量相关性要比单一波段更高,由倒数对数和一阶微分值计算的植被指数与叶绿素含量相关性反而低于单一波段。利用诊断波段的倒数后对数光谱特征值用于反演苗期冻害叶片叶绿素含量。

Based on the plotted plant and frostbite simulation experiment with frost box equipment, found out that the Chlorophyll content and photosynthesis and transpiration rate were lower than those of control group, respectively. According to the correlation analysis between chlorophyll and hyperspectral reflectance ρ of the leaf, logarithm of the reciprocal of ρ, the first derivative of ρ, the highest correlation bands concentrated on red and neared bands in control group, while the frostbitten group on blue, green and red bands. In terms of distinct difference analysis, the values of the reflectance and the first derivative were difficult as frostbitten diagnosis bands, but B696, B720, B768, B845 can be as diagnosis bands while utilizing Log（1/ρ）. The correlation coefficient between vegetation index of the reflectance and Chlorophyll content was higher than single band＇s. Selected diagnosis bands can be as variables in the regression function on the Chlorophyll content in terms of the value of Log（1/ρ）.