低温胁迫下毛竹叶片色素质量分数与反射光谱的相关性

为了探讨低温处理后毛竹Phyllostachys edulis叶片反射光谱特性与色素质量分数的相互关系,筛选出能够准确监测低温胁迫下毛竹伤害程度的光谱参数。测定了低温处理后毛竹叶片色素质量分数与反射光谱的变化参数,分析叶片光谱反射率、微分光谱及特征参数与色素质量分数的相关性。结果表明:随着温度的降低,叶绿素a和类胡萝卜素质量分数呈下降趋势(P<0.01)。反射光谱参数光谱反射指数、改良红边比、色素比值指数、归一化植被指数、红边归一化指数、改良类胡萝卜素指数和光化学反射指数等均随着温度的降低而降低(P<0.01);红边面积随着胁迫加深不断减小,红边位置向短波方向移动。在绿光区和红光区,叶绿素a和类胡萝卜素质量分数与光谱反射率及微分光谱显著相关(P<0.05),且与大部分光谱参数达到极显著相关(P<0.01),说明反射光谱特征及其参数可用来估算叶片色素质量分数。图4表5参40

Pigment content correlated to reflectance spectrums in Phyllostachys edulis leaves stressed by low temperature

The reflectance spectrum for photosynthetic pigments of Phyllostachys edulis，a widely distributed，important bamboo with high economic value in China，has a close relationship to the growth process of P. edulis leaves. To evaluate the relationship between reflectance spectra characteristics and pigment content，and to seek sensitive spectral parameters for exact estimations of damage in P. edulis leaves stressed by low temperature，pigment content and reflectance spectra indexes，such as spectral reflectance index wavelength of 705 nm（SR₇₀₅），modified spectral ratio（mSR），pigment-specific simple ratio（PSSR），normalized difference vegetation index（NDVI），red NDVI（rNDVI），memory carotenoid reflectance index （Mcri），and photochemical reflectance index（PRI），in P. edulis leaves under low temperature stress were tested and a correlation analysis was used for comparison. Results showed that as temperature deceased， chlorophyll a content and carotenoids in the leaves significantly decreased（P＜0.01）. As the stress level increased，reflectance spectrum parameters（SR₇₀₅，mSR，PSSR，NDVI，rNDVI，Mcri，and PRI）significantly decreased（P＜0.01）. The red-edge area（S_red）decreased，and the red-edge inflection（λ_red）position moved toward the short-wave direction with increasing stress. Significant correlations（P＜0.05）were found for chlorophyll a content, carotenoids in the leaves and reflectance spectra characteristics, and first derivative of reflectance spectra at the wavelength regions for blue edge and red edge. Moreover, correlations were significant（P＜0.01） between pigment content and spectral characteristic parameters of SR₇₀₅（r = 0.709），rNDVI（r = 0.724），Mcri（r = 0.706），and S_red（r = 0.706）. These reflectance spectrum parameters（PSSR，NDVI，rNDVI，and Sred）could be used to evaluate leaf pigment content.［Ch，4 fig. 5 tab. 40 ref.］