The plant canopy temperature provides a measure of the plant response to its environment and has been recognized as a sensitive indicator of plant water status (Jackson et al., 1981; Idso, 1982). The relationships between canopy temperature, air temperature and transpiration depend on atmospheric conditions (vapour pressure deficit, air temperature and wind velocity), the soil (mainly available soil moisture) and the plant (canopy size, canopy architecture and leaf adjustments to water deficit). Plants regulate their leaf temperatures by varying stomatal aperture to adjust the amount of water that is transpired. The evaporation of water cools the leaf. This natural system works well if there is adequate water for evaporation, and if the plant has roots to draw sufficient water into its vascular network. Plant water deficit develops when the demand exceeds the supply of water. The demand for water is set by atmospheric conditions, mainly radiation, atmospheric vapour pressure deficit and wind.

Main Research: Dr Mohd Haniff Harun