Realization of agricultural crop condition through field survey is quite expensive, time consuming and sometimes not practical for remote locations. Optical remote sensing techniques can provide information on real condition of the crops by observing spectral reflectance at different crop growth phases and is less expensive and less time consuming. Hyperspectral remote sensing provides a unique opportunity for non-destructive, timely and accurate estimation of crop biophysical and biochemical properties. In this study, a field experiment was conducted to identify the water and nitrogen stress indicative spectral bands using ground-based hyperspectral data and to assess the predictive capability of selective bands on yield of maize under water and nitrogen stress environment. The experiment comprised of three irrigation scheduling treatments based on IW/CPE ration of 0.6, 0.8 and 1.2 and three nitrogen level treatments, i.e., 100, 200 and 300 kg of N ha−1, respectively, with three replications in a split plot design. The spectral reflectance was measured before irrigation at tasseling and dough stage of the maize crop using portable field spectroradiometer. The results of stepwise multiple linear regression indicated the highest predicting capability of spectral bands 540 nm, 780 nm and 860 nm for leaf nitrogen and 700 nm, 740 nm and 860 nm for leaf water content. The derived biophysical parameters based on spectral reflectance viz. relative leaf water content (%), leaf area index and leaf nitrogen contentment (%) at tasseling stage of maize crop accounted for 80%, 61% and 66% variation in grain yield, respectively.

中文翻译：

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利用高光谱遥感在后季风季节识别玉米水分和氮胁迫指示光谱带

通过实地调查了解农作物状况非常昂贵、耗时，有时对于偏远地区来说不切实际。光学遥感技术可以通过观察作物不同生长阶段的光谱反射率来提供作物真实状况的信息，并且成本更低、耗时更少。高光谱遥感为非破坏性、及时和准确估计作物生物物理和生化特性提供了独特的机会。本研究通过田间试验，利用地基高光谱数据识别水氮胁迫指示谱带，并评估选择性谱带对水氮胁迫环境下玉米产量的预测能力。试验包括基于 0.6、0.8 和 1.2 的 IW/CPE 配比的三种灌溉调度处理和三种氮水平处理，即分别为 100、200 和 300 kg N ha-1，在裂区设计中重复三次. 使用便携式现场光谱辐射计测量玉米作物在雄蕊和面团阶段灌溉前的光谱反射率。逐步多元线性回归结果表明，540 nm、780 nm 和860 nm 波段对叶氮含量的预测能力最高，在700 nm、740 nm 和860 nm 波段对叶片含水量的预测能力最高。基于光谱反射率的衍生生物物理参数，即。玉米抽穗期的相对叶含水量(%)、叶面积指数和叶氮含量(%)分别占籽粒产量的80%、61%和66%的变异。