铜胁迫下玉米叶片反射光谱的红边位置变化及其与叶绿素的关系

摘要

The effects of Cuprum stress on reflectance spectra and chlorophyll content of maize leaves were studied by corn plant-ing under 5 different Cu2+concentration treatment.During the indoor experiment,hyperspectral reflectance and the correspond-ing contents of chlorophyll of leaves of maize seedling were measured and their changing trends and relationships between Cu 2+concentration,chlorophyll content and red edge position(wavelength of reflection spectra)were analyzed.Results showed that the corn leaf reflection spectra had the obvious"blue shift of red edge"phenomenon,namely the red edge position of leaf spectra moved to short wave.The red edge position significantly correlated to Cuprum concentration(R=0.76),i.e.the blue shift of red edge increased with Cuprum concentration.In the meanwhile red edge blue-shifts increased with the extension of stress time. The chlorophyll a,chlorophyll b content and their ratio(Chla/Chlb)were significantly different between the five stress treat-ments(p=0.002,0.007,0.001).The content of chlorophyll covaried with Chla/Chlb.At the same time,Chla/Chlb and the concentration of Cuprum in the culture solution showed negative and significant correlation(r= -0.898),whilst,Chla/Chlb was significant and positively correlated with the mean red edge position(r=0.814).These results indicated that the blue shift of red edge of the reflectance spectra in the leaves of maize caused by Cuprum stress should attributed to the increase of chloro-phyll b relative to chlorophyll a,which changed the leaf absorption spectrum and altered the red edge position of leaf reflectance.%采用5级梯度铜胁迫砂培试验,通过测定叶片反射光谱曲线和叶绿素含量,研究铜胁迫对玉米叶片反射光谱与叶绿素含量的影响.研究表明:玉米叶片反射光谱的红边位置与铜胁迫浓度显著相关(R2≥0.5755),且存在明显的"红边蓝移"现象,即叶片光谱红边位置向短波方向移动.随着铜胁迫浓度的升高或胁迫时间延长,红边蓝移程度增加.不同胁迫浓度之间,叶绿素a、叶绿素b含量及二者比值(Chla/Chlb)均差异显著(p分别为0.002,0.007和0.001).叶绿素a、b比值(Chla/Chlb)与培养液中铜浓度呈显著负相关(R= -0.898);Chla/Chlb与平均红边波长显著正相关(R= 0.814).这表明随着铜胁迫浓度升高,Chla/Chlb降低,叶绿素b相对于叶绿素a升高,叶片反射光谱的红边位置蓝移.铜胁迫改变了玉米叶片中Chla和Chlb含量和比值,由此导致的色素吸收光谱变化,是铜胁迫导致叶片反射光谱红边蓝移的可能的生理学成因.