■可见光中的高光谱反射率数据,近红外和短波红外范围(VIS-NIR-SWIR,400-2500nm)通常用于无损测量植物叶片特性。我们调查了VIS-NIR-SWIR作为一种高通量工具的有用性,用于测量玉米植物的六种叶片特性,包括叶绿素含量(CHL)。叶片含水量(LWC),比叶面积(SLA),氮(N),磷(P),钾(K)。使用玉米多样性小组的品系进行该评估。数据是从温室条件下生长的植物中收集的,以及在两种施氮制度下的野外。用VIS-NIR-SWIR光谱辐射计在抽穗时收集叶级高光谱数据。两种多变量建模方法,偏最小二乘回归(PLSR)和支持向量回归(SVR),用于从高光谱数据中估计叶片特性。几种常见的植被指数(VIs:GNDVI,伦迪威,和NDWI),根据高光谱数据计算,还评估了这些叶子的特性。
■一些VI能够估计CHL和N(R2>0.68),但未能估计其他四个叶子的属性。使用PLSR和SVR开发的模型表现出彼此可比的性能,并提供了相对于VI模型提高的准确性。CHL估计最成功,R2(测定系数)>0.94,性能偏差比(RPD)>4.0。N也令人满意地预测(R2>0.85和RPD>2.6)。LWC,SLA和K的预测适中,R2为0.54至0.70,RPD为1.5至1.8。预测精度最低的是P,R2<0.5和RPD<1.4。
■这项研究表明,VIS-NIR-SWIR反射光谱是低成本,非破坏性的,和高通量分析叶片的许多生理生化特性。与基于VI的方法相比,基于全光谱的建模方法(PLSR和SVR)导致更准确的预测模型。我们呼吁建立叶片VIS-NIR-SWIR光谱库,这将极大地有利于植物表型群落,用于植物叶片性状的研究。
UNASSIGNED: Hyperspectral reflectance data in the visible, near infrared and shortwave infrared range (VIS-NIR-SWIR, 400-2500 nm) are commonly used to nondestructively measure plant leaf properties. We investigated the usefulness of VIS-NIR-SWIR as a high-throughput tool to measure six leaf properties of maize plants including chlorophyll content (CHL), leaf water content (LWC), specific leaf area (SLA), nitrogen (N), phosphorus (P), and potassium (K). This assessment was performed using the lines of the maize diversity panel. Data were collected from plants grown in greenhouse condition, as well as in the field under two nitrogen application regimes. Leaf-level
hyperspectral data were collected with a VIS-NIR-SWIR spectroradiometer at tasseling. Two multivariate modeling approaches, partial least squares regression (PLSR) and support vector regression (SVR), were employed to estimate the leaf properties from
hyperspectral data. Several common vegetation indices (VIs: GNDVI, RENDVI, and NDWI), which were calculated from
hyperspectral data, were also assessed to estimate these leaf properties.
UNASSIGNED: Some VIs were able to estimate CHL and N (R2 > 0.68), but failed to estimate the other four leaf properties. Models developed with PLSR and SVR exhibited comparable performance to each other, and provided improved accuracy relative to VI models. CHL were estimated most successfully, with R2 (coefficient of determination) > 0.94 and ratio of performance to deviation (RPD) > 4.0. N was also predicted satisfactorily (R2 > 0.85 and RPD > 2.6). LWC, SLA and K were predicted moderately well, with R2 ranging from 0.54 to 0.70 and RPD from 1.5 to 1.8. The lowest prediction accuracy was for P, with R2 < 0.5 and RPD < 1.4.
UNASSIGNED: This study showed that VIS-NIR-SWIR reflectance spectroscopy is a promising tool for low-cost, nondestructive, and high-throughput analysis of a number of leaf physiological and biochemical properties. Full-spectrum based modeling approaches (PLSR and SVR) led to more accurate prediction models compared to VI-based methods. We called for the construction of a leaf VIS-NIR-SWIR spectral library that would greatly benefit the plant phenotyping community for the research of plant leaf traits.