芜菁营养生长期叶片光谱特性及对氮的敏感性

【目的】分析芜菁营养生长期叶片光谱反射率对N的响应,研究采用叶片光谱指数诊断N敏感时期,为新疆芜菁简便快捷的非破坏性N营养诊断提供最佳时间窗。【方法】利用Unispec-SC光谱仪测定不同芜菁幼苗期、叶片生长旺盛期、肉质根生长盛期、成熟期叶片的光谱反射率。【结果】芜菁营养生长期叶片光谱反射率波动取决于波长,在可见光波段的变异最小。芜菁营养生长期不同发育阶段光谱指数(ND₇₀₅)之间均存在显著差异(P＜0.05)或者极显著差异(P＜0.01)。【结论】叶片生长旺盛期为长黄蔓菁、新星圆蔓菁、美国小芜菁、天地禾芜菁氮素光谱营养诊断的敏感时期,叶片生长旺盛期与肉质根生长盛期为新星圆蔓菁(二代)氮素光谱营养诊断的敏感时期。幼苗期和成熟期可以作为区分几个品种芜菁氮素光谱营养诊断的敏感生育期。

Leaf Spectral Characteristics and Its Sensitivity to N in Different Vegetative Growth Stages of Turnips

【Objective】 The sensitive period of leaf spectral index was studied by analyzing the leaf spectral reflectance in the response to Nitrogen (N) fertilizer at different growing stages of different turnip cultivars in Xinjiang aiming to provide a non-invasive,simple and rapid nutrition diagnosis of N.【Method】The spectral reflectance of different turnip seedling stages, leaf growth exuberant stage, fleshy root growth peak stage and mature stage were measured by Unispec-SC spectrometer with different turnip cultivars as the test material.【Result】The fluctuation of leaf spectral reflectance of different turnip cultivars depended on the wavelengths at all the growing stages,and the least variation was in the range of visible wavelength. The leaf spectrum indexes (ND₇₀₅) of different turnip cultivars were significant (P < 0.05) and extremely significant (P < 0.01) different at all growing stages.【Conclusion】Spectral sensitive period of foliar N concentration varied during different growing stages. The sensitive period for leaf spectral nutrition diagnosis in response to N of long and yellow turnip, Xinxing round turnip, American turnip and Tiandihe turnip were leaf exuberant growth period. The sensitive period for leaf spectral nutrition diagnosis in response to N of Xinxing round turnip (second generation) turnip are leaf exuberant growth period and fleshy root growth stage. The seedling stage and fruit mature period can be used to distinguish several varieties of turnip diagnosis of nitrogen sensitive growth stage.