小麦叶片氮素状况与光谱特性的相关性研究  

CORRELATION BETWEEN LEAF NITROGEN STATUS AND CANOPY SPECTRAL CHARACTERISTICS IN WHEAT

作　　者：薛利红[1] 曹卫星[1] 罗卫红[1] 张宪[1] 

机构地区：[1]南京农业大学农业部作物生长调控重点开放实验室,南京210095

出　　处：《植物生态学报》2004年第2期172-177,共6页Chinese Journal of Plant Ecology

基　　金：国家自然科学基金重点项目 ( 3 0 0 3 0 0 90 );国家 863计划项目 ( 2 0 0 2AA2 43 0 11)

摘　　要：系统分析了不同时相下两个小麦 (Triticumaestivium)品种叶片含氮量及叶片氮积累量与冠层光谱反射特征的关系。结果表明 ,随施氮水平的增加 ,小麦冠层在可见光区的反射率逐渐降低 ,而近红外波段的反射率逐渐升高。小麦叶片氮素状况与比值指数或归一化指数显著相关 ,两个品种表现极为一致 ,可以用一个指数方程来拟合。分阶段建模并没有提高模型的精度 ,因此可以建立一个适用于整个生育时期的通用氮素诊断方程。叶片含氮量同光谱指数在整个生育期内的关系要优于叶片氮积累量的 ,其中 ,与叶片含氮量关系最佳的指数为红波段 (6 6 0nm)和蓝波段 (4 6 0nm)的组合 (R2 >0 .80 ) ;与叶片氮积累量关系最佳的光谱指数为中红外波段 (1 2 2 0nm)与红波段 (6 6 0nm)的组合 (R2 >0 .6 2 )。Non_destructive monitoring and diagnosis of plant nitrogen (N) status is necessary for precision N management. The present study was conducted to determine if canopy reflectance could be used to evaluate leaf N status in wheat ( Triticum aestivium ) of two cultivars, `Huaimai 18' and `Xuzhou 26'. Ground_based canopy spectral reflectance, leaf N concentration and leaf N accumulation were measured at seven growth stages (jointing, booting, heading, anthesis, initial filling, mid_filling and late filling) under four different treatments of N fertilization (0, 12, 21 and 30 g N·m -2 ). Analyses were made on the relationships of seasonal canopy spectral reflectance, ratio indices ( R(λ 1,λ 2)=ρ λ 1 /ρ λ 2 ) and normalized difference indices ( ND(λ 1,λ 2)=|ρ λ 1 -ρ λ 2 |ρ λ 1 +ρ λ 2 ) to leaf N concentration and N accumulation in wheat under different N treatments at different growth stages and during the whole growing season. The results showed that canopy spectral reflectance in the near infrared increased with increasing N content, whereas reflectance in the visible band decreased. Leaf N status was significantly correlated with the ratio or normalized difference indices in both cultivars. Regression models of leaf N status to spectral indices based on single growth stages did not improve the prediction over whole growth cycle; hence, a single regression model based on the whole growth cycle should be adequate for diagnosing N status in wheat plants. The relationships between leaf N concentration and spectral indices were better than those of leaf N accumulation. The best indices were the combination of a MIR (mid_infrared) band (1 220 nm) and red band (660 nm) for leaf N concentration ( LNC=3.894 5×R(660, 460) -1.028 7 , R 2=0.834 2; LNC=3.918 7×e -2.179 6ND(660,460) , R 2=0.835 2) and the combination of the red band (660 nm) and blue band (460 nm) for leaf N accumulation LNA=1.55×e 0.115 3R(1 220, 660) , R 2=0.724 2; LNA=0.219 4�

关 键 词：小麦 叶片 氮素 光谱特性 相关性 比值指数 归一化指数 回归模型 生育期 

分 类 号：S512.1[农业科学—作物学]