Remote-monitoring of physiological and ecological status of crops by means of multi-sensing, 3: Quantitative analyses of the transpiration and stomatal responses to drought stress and relationship between photosynthesis and transpiration
1991
Inoue, Y. (Agricultural Research Center, Tsukuba, Ibaraki (Japan))
The objective of this study is to develop remote monitoring methods for evaluating the physiological and ecological status of crop plants under field conditions. In the present paper, preliminary analyses were performed for remote estimation of physiological responses to drought stress and of photosynthetic activity on the basis of field experiments in wheat, corn, soybean, and cotton. 1. The responses of transpiration (Tr) and stomatal resistance (rs) to the amount of extractable water in soil and the vapor pressure deficit of thee air (VPD) were investigated in wheat under different irrigation conditions during an entire growing season. 2. The relationship between the photosynthetic and transpiration rates and related stomatal behavior were investigated quantitatively on the basis of gas and moisture exchange processes via stomata and the boundary layer. Data of photosynthetic and transpiration rates were obtained in corn, soybean and cotton under various micro-meteorological conditions including elevated atmospheric CO2 concentration. The influence of the leaf chlorophyll content on the photosynthetic rate was also examined. 3. Water use efficiency as defined from the gas and moisture exchange processes in a leaf was shown to be estimated using the leaf temperature and the difference between the ambient and substomatal CO2 concentrations (Ca-Cl)
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