不同氮水平枣树冠层光谱特征

利用FieldSpec Pro FR2500光谱仪测定不同氮素处理下的红枣冠层光谱,分析其光谱特征变化规律及其与枣叶全氮质量分数的相关关系,旨在为枣树氮素营养的无损诊断提供理论基础。结果表明:同一氮处理水平下,红枣叶片展叶期的全氮质量分数最高,摘心前期最低。随着施氮量的增加,展叶期和摘心后期枣叶全氮质量分数增加速度较快。不同氮处理的枣树冠层波谱曲线整体变化趋势为在560nm附近和750~1 100nm分别有1个反射峰,反射率值分别达0.1~0.2和0.4以上;而在450、650、1 450、1 950和2 600nm处有5个吸收谷。不同生育期枣叶全氮质量分数与冠层光谱红边参数显著相关,且摘心后期红边位置(REP)和红谷位置(Lo)更快地向短波方向移动,出现"蓝移"现象。

Study on Canopy Spectral Characteristics of Jujube Canopy in Different Nitrogen Level

Using the FieldSpec Pro FR2500 spectrometer, canopy spectra of red jujube under different nitrogen treatments were estimated, and the spectrum characteristic change rule and its correlation with red jujube and leaf total nitrogen mass fraction were analyzed. The results showed that the value of leaf total nitrogen in exhibition leaf stage was the highest, the least at the early stage of the pinching period, and with the increase of nitrogen application, the leaf total nitrogen increased quickly in exhibition leaf and the late pinching period: under same nitrigen treatment. The spectral curve had reflection peak near 560 nm in visible bands and 750 nm to 1 100 nm, respectively under different nitrogen treatments, and the reflectance was 0.1-0.2, great than 0.4, respectively. While, there were five absorption valleys in 450 nm, 650 nm 1 450 nm, 1 950 nm and 2 600 nm. The relationship between leaf total nitrogen and canopy reflectance characteristicsat different stage was significant, the red edge position(REP) and location(Lo) shift to the short wavelength direction rapidly.In conclusion,it is beneficial to jujube nitrogen prediction by using remote sensing technology, and can lay the foundation for jujube nondestructive nutrition diagnosis.