基于光谱水分指数的核桃叶片含水量估算模型  

Estimation Models for Water Content of Walnut Leaves Based on Spectral Moisture Index

作　　者：胡珍珠[1] 潘存德[1] 潘鑫[1] 朱白雪 

机构地区：[1]新疆农业大学林学与园艺学院新疆教育厅干旱区林业生态与产业技术重点实验室,乌鲁木齐830052

出　　处：《林业科学》2016年第12期39-49,共11页Scientia Silvae Sinicae

基　　金：新疆维吾尔自治区"十二五"重大科技专项课题(201130102-2);新疆研究生科研创新项目(XJGRI2014082)

摘　　要：【目的】采用光谱技术定量反演果实不同生育时期叶片含水量,为新疆南疆盆地人工绿洲核桃节水灌溉与水分管理提供技术支持。【方法】以‘温185’核桃叶片为研究对象,利用Uni Spec-SC便携式光谱仪测定核桃果实不同生育时期的叶片光谱反射率,以水分指数(WI)、水分波段指数(WBI)、归一化水分指数(NDWI)、比值指数(WI/NDWI)、中心波长比值指数(Ratio975)和光化/生理反射(PRI)6种光谱水分指数为自变量,分别采用一元线性回归(MLR)、多元线性逐步回归(SMLR)、主成分回归(PCR)和偏最小二乘回归(SPLR)构建‘温185’核桃果实坐果期、速生生长期、硬核期、脂化期和近成熟期叶片含水量的光谱估算模型,并利用独立样本对模型精度进行检验和评价。【结果】在可见光波段,光谱反射率随叶片含水量的增加而增大,而在近红外波段,随叶片含水量的增加光谱反射率则呈减弱趋势,且绿光、黄光、红光、近红外光波段均是‘温185’核桃叶片水分含量的光谱敏感波段。果实不同生育时期叶片含水量与光谱水分指数的相关性虽均达极显著水平(P<0.01),但相关系数绝对值的大小有较大差异。采用不同方法所构建的叶片含水量光谱估算模型中,果实坐果期、硬核期、脂化期和近成熟期以SMLR模型拟合度(R^2)最高,均在0.82以上,果实速生生长期则以PCR模型拟合度(R^2)最高,达到0.877 4,且采用独立样本对2种回归模型检验的均方根误差(0.613 7 g·kg^(-1)≤RMSE≤5.774 6 g·kg^(-1))和相对误差(0.818 2%≤RE≤2.977 5%)均较小,并均通过置信椭圆检验,模型估算值与实测值一致;而构建的果实不同生育时期叶片含水量MLR和SPLR模型拟合度(R^2)均较低,且均方根误差(1.021 0 g·kg^(-1)≤RMSE≤11.205 6 g·kg^(-1))和相对误差(1.109 7%≤RE≤3.680 8%)较大,表明模型估算效果均较差。【结论】所筛选的‘温185’核桃果实坐果期、硬核�【Objective】Foliar water content of walnut was monitored quantitatively by the spectral technique to provide the technical support for water-saving agricultural production and water management in artificial oasis in southern Xinjiang basin. 【Method】Based on both spectral reflectance measurement by Uni Spec-SC portable spectrometer and foliar water content measured by dry-weight method in laboratory,the foliar water content estimation models for Juglans regia‘Wen185＇at the fruit setting period,fruit rapid-growth period,fruit hard-core period,fruit fat-change period and fruit near-mature period were established with monadic linear regression model,stepwise multiple linear regression model,principle component regression model and partial least squares regression model. The six water indexes of spectral indices：water index（ WI）,water band index（ WBI）,normalized difference water index（ NDWI）,the ratio index（ WI / NDWI）,center wavelength water index（ Ratio975） were used for constructing the estimation models. The accuracy of these models was tested and evaluated by independent samples. 【Result】The results showed that the spectral reflectance of J. regia‘Wen185＇increased with leaf water content increasing in visible waveband,while weaken with the foliar water content increasing in the near infrared wave band. In addition,the green light,yellow light,red light and near infrared light were the sensitive spectral bands for the J. regia ‘Wen185 ＇. There were significant correlations（ P〈0. 01） between foliar water content and spectral water index but with different values of correlation coefficients. The results also showed that stepwise multiple linear regression model was suitable for fruit setting period,fruit rapid growth period,fruit hard-core period and fruit fat-change period with R^2 all above 0. 82,while principle component regression model had the highest determination coefficient R^2 of 0. 877 4 at the fruit near-mature period. Independent samples were used to tes

关 键 词：核桃 叶片 含水量 光谱 光谱水分指数 回归分析 估算模型 

分 类 号：S664.1[农业科学—果树学]