不同供氮水平下水稻高光谱及其红边特征研究

Hyperspectral Data and Their Relationships Correlative to the Pigment Contents for Rice Under Different Nitrogen Support Level

通过大田和室内试验 ,测定了 3个供氮水平下 2个品种的水稻冠层、主茎叶片在不同发育期的高光谱反射率及对应的叶绿素、类胡萝卜素含量。结果表明 :不同供氮水平的水稻冠层和叶片光谱差异明显 ,其光谱反射率随供氮水平的提高在可见光范围降低 ,在近红外区域增高 ;拔节期和孕穗期主茎倒三叶反射率在可见光和近红外区域均高于倒一叶 ;冠层光谱红边位置λred、红边幅值Dλred和红边面积Sred孕穗前呈“红移” ,抽穗后呈“蓝移”现象 ;叶面积指数LAI、地上鲜生物量AFM、地上干生物量ADM和鲜叶重FLM与冠层光谱变量R12 0 0 /R550 ,R990 /R550 ,R80 0 /R550 ,R750 /R550 ,λred,Sred之间有极显著相关 ,冠层和叶片色素含量与其光谱变量R80 0 /R550 和λred之间也存在显著相关。这说明用合适的高光谱变量来估算水稻LAI,AFM ,ADM ,FLM和冠层。

The hyperspectral reflectances of the canopy, the leaf on the main stem of two varieties of rice are measured by a ASD FieldSpec Pro FR FM in field and indoor under 3 nitrogen support levels in different stages. The contents of chlorophyll and carotenoid of canopies and leaves corresponding to the spectra were determined. The spectral difference are clear for the canopy and leaves of rice under different nitrogen levels, and the spectral reflectance are gradually getting smaller in the visible region and bigger in the near infrared region along with nitrogen level increasing. The spectral reflectance of the third unfolding leaf from the top on the main stem were bigger than that of the first one from the top in the visible region and the near infrared region at jointing stage and booting stage. There were `red shift' phenomena before booting and `blue shift' after heading for the position of red edge λ red, slope of red edge Dλ red and area of red edge S red of the canopy spectra. The leaf area indices(LAI), above ground fresh biomass(AFM), above ground dry biomass(ADM) and fresh leaf mass(FLM) were very significantly correlative to the spectral variables R 1200/R 550, R 990/R 550, R 800/R 550, R 750/R 550, λ red and S red. The pigment contents of canopies and leaves were also significantly correlative to the spectral variables R 800/R 550 and λ red. This indicated that some right spectral variables would be used to estimate the LAI, AFM, ADM, FLM and the pigment contents of canopy and leaf for rice.