Biophysical controls of evapotranspiration in cowpea cultivation under different water regimes

Abstract

The objective of this study was to analyze the variations of the decoupling factor and the aerodynamic and stomatal conductances for cowpea subjected to different levels of water availability during the reproductive phenological stages of the crop. The study was conducted in the municipality of Castanhal located in the northeast of the state of Pará, Brazil, in an area planted with cowpea, in 2013, 2014 and 2015 with four irrigation treatments: T100 - replacement of 100% of the crop evapotranspiration (ETc); T50 - replacement of 50% ETc; T25 - replacement of 25% ETc; and T0 - without any replacement (without irrigation). The interaction between the crop and the atmosphere in water vapor exchange was estimated through the decoupling factor (Ω), which was between 0.5 and 1, except for the treatment without irrigation, indicating a moderate to high decoupling between the crop and the atmosphere, so that the water vapor exchange process was controlled by the energy supply, instead of stomatal control.

Crop Water Stress Index of Cowpea Under Different Water Availability Levels in Castanhal-Pa

“…Environmental conditions have great interference in plant development (FARIAS et al, 2017;SOUZA et al, 2019), and water deficit is one of the main factors that limit crop yield, since the stomata are the main route for CO 2 assimilation and water loss through transpiration (TAIZ; ZEIGER, 2017).…”

“…The absence of adequate amount of water in the soil affects the physiological activities of the plant, varying according to frequency, intensity and genotype (SOUZA et al, 2019), and to avoid water loss to the atmosphere, crops use strategies such as leaf area reduction, leaf abscission and stomatal closure (FREITAS et al, 2017). These strategies reduce photosynthesis and transpiration, compromising the production of photoassimilates and decreasing the dissipation of plant heat to the atmosphere, thus causing a thermal stress in the plant (JAGADISH et al, 2021).…”