The potential of the spectral ‘water balance index’ ( WABI ) for crop irrigation scheduling

Abstract

Summary Hyperspectral sensing can detect slight changes in plant physiology, and may offer a faster and nondestructive alternative for water status monitoring. This premise was tested in the current study using a narrow‐band ‘water balance index’ ( WABI ), which is based on independent changes in leaf water content (1500 nm) and the efficiency of the nonphotochemical quenching ( NPQ ) photo‐protective mechanism (531 nm). The hydraulic, photo‐protective and spectral behaviors of five important crops – grapevine, corn, tomato, pea and sunflower – were evaluated under water deficit conditions in order to associate the differences in stress physiology with WABI suitability. Rapid alterations in both leaf water content and NPQ were observed in grapevine, pea and sunflower, and were effectively captured by WABI . Apart from water status monitoring, the index was also successful in scheduling the irrigation of a vineyard, despite phenological and environmental variability. Conversely, corn and tomato displayed a relatively strict stomatal regime and/or mild NPQ responses and were, thus, unsuitable for WABI ‐based monitoring. WABI shows great potential for irrigation scheduling of various crops, and has a clear advantage over spectral models that focus on either of the abovementioned physiological mechanisms.

Plant phenotyping relevance

WABIというスペクトル指標を用いた植物水分状態・生理状態の非破壊推定法を複数作物で評価し、灌漑スケジューリングへの適用性も検証しており、表現型取得法が中心である。

Code and data availability

The supplied article blocks describe net house, field, and vineyard spectral-physiological experiments (WABI) but contain no data availability statement, no public phenotype/spectral dataset, no author code or model deposit, and no repository identifiers. The only URLs present are the article's own Wiley download/terms

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