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

Tal Rapaport, Uri Hochberg, Amnon Cochavi, Arnon Karnieli, Shimon Rachmilevitch

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


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.

Original languageEnglish
Pages (from-to)741-757
Number of pages17
JournalNew Phytologist
Issue number3
StatePublished - 1 Nov 2017


  • crop physiology
  • hyperspectral spectroscopy
  • irrigation
  • precision agriculture
  • water balance index (WABI)

ASJC Scopus subject areas

  • Physiology
  • Plant Science


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