夏玉米红边参数特征及与叶绿素、干物质相关性的研究

Study on the Red Edge Characteristics of Summer Maize and Their Correlation to Chrolophyll and Dry Matter

分析不同氮素水平下夏玉米红边参数特征及其与叶绿素含量、干物质积累之间的相关性,建立基于红边参数的5种函数形式的色素含量、干物质积累估算模型。结果表明,玉米的冠层光谱红边具有"双峰"现象,随生育期推移,"双峰"现象先增强后减弱,开花期达到最大。红边位置随生育期向长波方向移动,呈现"红移"现象;开花后开始减小,呈现"蓝移"现象,且在施氮水平下,开花期至灌浆期之间出现"红边平台"现象。随着氮素水平的增加,红边位置(λred)变化不大,而红边幅值(D red)呈现逐渐增加的趋势。在相关分析中,红边位置与叶绿素a、叶绿素b、类胡萝卜素及叶绿素总量呈显著或极显著相关;红边幅值与干物质、叶绿素b相关性显著。通过建立的5种函数形式的估算模型得知,二项式函数回归模型优于线性、幂函数、指数以及对数回归模型等,估测精度较高,具有较好的预测能力。

The red edge characteristics of summer maize at different nitrogen levels and their relationships with the dry matter accumulation above ground and chlorophyll content were analyzed. Meanwhile, five function pattern of the chlorophyll content and dry matter accumulation modeling based on the red edge of summer maize was established. The results showed that there was ＂double peak＂ phenomenon for the red edge of canopy spectra in the summer maize, reaching its highest in the flowering period. There was ＂red shift＂ phenomenon for the position of red edge along with the growth period. While after the flowering period, presenting ＂blue shift＂. There was a red edge platform phe- nomenon for the position of red edge between the flowering period and filling period in nitrogen treatment. Along with the increase of nitrogen level, the position of red edge changed a little, but the slope of red edge appeared to be an in- creasing trend. The correlation between the position of red edge and chlorophyll content,chlorophyll a content, chlorophyll b content, carotenoid content was significant. Meanwhile, the significant correlation between the slope of red edge and the dry matter accumulation and chlorophyll b content was also shown. The results showed that the bino- mial function regression model was better than the model of liner, the power function, index and logarithm function, and it had good prediction ability.