Water deficit in common beans. IV. Micrometeorological modifications

Abstract

Micrometeorological modifications were evaluated in common bean (Phaseolus vulgaris L.) crops subject to varying conditions of soil-water availability, in an experiment conducted at Piracicaba, SP, Brazil, 22°42' south latitude and 576 m altitude. Common beans were sown in 30m x 20 m split-plots, on three dates (July 7, July 22, and August 4, 1983), each receiving two conditions of soil water availability with continued irrigation and with a period of water stress caused by an 18-day period without rain (Sept. 25 to Oct. 12). During the drought period, on days with high atmospheric evaporative demand, the temperature of the canopy surface (measured by a remote infrared sensor) was higher than air temperature close to the plants in the stressed crop, while the contrary occurred in the irrigated one. Soil water deficit increased the air temperature and the water vapor saturation deficit near the plants. Micrometeorological modifications were higher by the end of the drought period and during the warmer times of the days. They also were higher at the plots of the latest sowing date (lees developed plants). The micrometeorological conditions near the plants were in agreement with the crop energy balance.