Performance of two bean varieties under two different conditions of soil water availability. II. Stomatal diffusive resistance, to water vapor transpiration flow density, and leaf water potential

Abstract

A field trial was conducted in 1983 at Escola Superior de Agricultura "Luiz de Queiroz" (ESALQ) of Universidade Federal de São Paulo (USP) in Piracicaba, SP, Brazil, at latitude of 22.7°S, longitude 47.6°W, and altitude of 586 m a.s.l., in order to study differences in water requirements of two bean varieties (Phaseolus vulgaris L.), Aroana 80 and Aetê 3, and the influence of water stress on their development. Two different sowing times were used, at interval of 16 days. When the first plot was at bud initiation and the second plot at the pod initiation, sprinkler irrigation was suspended for a 17-day period. During this period the following parameters were measured: stomatal resistance to water vapor diffusion (Rd), density of transpiration flow (Tr) by means of a steady-state porometer (LI-COR, model 1600) and total leaf water potential using a hygrometric thermocouple (Wescor Inc. Model). Leaf adaxial faces presented higher Rd values than leaf adaxial superfaces on both varieties and sowing times over the whole period studied. The difference between leaf surfaces in relation to Rd values and flue absolute value for each leaf surface were generally higher in the variety Aroana 80. Tr values for leaf adaxial surfaces were always lower for Aeté 3 compared to Aroana 80.