基于无人机多光谱遥感的水稻冠层光谱特征和氮素营养关系研究

Research on Relationship Between Canopy Spectral Characteristics and Nitrogen Nutrient of Rice Cultivars Based on UAV Multispectral Remote Sensing

【目的】明确华南地区籼稻主栽品种冠层光谱特征与氮素营养关系,为专家决策系统和精准施肥提供理论基础。【方法】以美香占2号(MXZ2H)和吉丰优1002(JFY1002)为试材,设置施氮0 kg/hm2(N0)、150 kg/hm2(N150)、210 kg/hm2(N210)等3个处理,采用习惯施肥法,在JFY1002中增设施氮180 kg/hm2(N180+)的水稻“三控”施肥法,研究不同施肥方式下水稻叶片光谱特征与氮素营养的关系。【结果】与N0相比,N150处理下MXZ2H和JFY1002叶片氮含量分别增加16.05%和13.76%,N210处理分别增加24.29%和25.00%。N180+处理下JFY1002叶片氮含量与N210处理相比增加18.03%。随着叶片氮含量的增加,蓝光到红光(450~650 nm)波段的叶片反射率逐渐下降,红边到近红外(730~840 nm)波段的叶片反射率逐渐增加,红光650 nm、近红外840 nm处的MXZ2H和JFY1002叶片反射率差异达显著水平。相关性分析结果表明,MXZ2H叶片氮含量与归一化植被指数(NDVI)、绿波段归一化植被指数(GNDVI)、比值植被指数(RVI)、差值植被指数(DVI)和增强型植被指数(EVI)呈正相关;JFY1002叶片氮含量与RVI、EVI、改进非线性植被指数(MNLI)、DVI和NDVI呈正相关。采用多元线性回归建立了MXZ2H和JFY1002叶片氮含量反演模型,R2分别为0.817和0.973,RE分别为8.35%和3.48%。【结论】建立了华南籼稻品种叶片氮含量反演模型,可为精准施肥作业提供理论依据和技术指导。

【Objective】The relationship between canopy spectral characteristics and nitrogen nutrient of main cultivated indica rice cultivars in South China was determined,which provided theoretical basis for expert decision making system and precise fertilization.【Method】A conventional indica rice Meixiangzhan 2(MXZ2H)and a hybrid indica rice Jifengyou 1002(JFY1002)were selected as test materials,with three nitrogen levels including 0 kg/hm2(N0),150 kg/hm2(N150)and 210 kg/hm2(N210)using farmers’practice(FP).The“Three Control”fertilization technique with nitrogen rate of 180 kg/hm2(N180+)was added in the field experiment with JFY1002 rice cultivar,and the relationship between rice leaf spectral characteristics and nitrogen nutrient was explored.【Result】Compared with N0 treatment,the leaf nitrogen concentration of MXZ2H and JFY1002 were increased by 16.05%and 13.76%under N150 treatment,and by 24.29%and 25.00%under N210 treatment,respectively.Leaf nitrogen concentration of JFY1002 was increased by 18.03%under N180+treatment compared with that under N210 treatment.With the increase of leaf nitrogen concentration,the spectral reflectance of leaves from blue band to red band(450-650 nm)were decreased gradually,but that from red edge band to near infrared band(730-840 nm)were increased gradually.Significant difference was found in the spectral reflectance of MXZ2H and JFY1002 at 650 nm red band and 840 nm near infrared band.The results of correlation analysis showed that the leaf nitrogen concentration of MXZ2H was positively correlated with NDVI,GNDVI,RVI,DVI,and EVI,and that of JFY1002 was positively correlated with RVI,EVI,MNLI,DVI and NDVI.The inversion models of leaf nitrogen concentration of MXZ2H and JFY1002 were established with R2 of 0.817 and 0.973,and with RE of 8.35%and 3.48%,respectively.【Conclusion】The study established an inversion model of leaf nitrogen concentration for indica rice cultivars in South China,which provided theoretical basis and technical guidance for precise fertilization operation of rice.