Water deficit in common beans. I. Growth analysis and phenology

Abstract

Growth parameters and phenology of common beans (Phaseolus vulgaris L.) were evaluated in 1983 under different soil moisture conditions in a field experiment conducted at Piracicaba, SP, Brazil, 22^o43'30" south latitude and 576 m altitude. Common beans cv. Aroana 80 were sown in three dates: July 7, July 22 and August 4. During a period without rain (Sept. 25 to Oct. 12), half of the plants, in various growth stages, were kept under soil water deficit. Water deficit by the end of the grain filling period did not affect cycle duration. However, the maturation was hastened when the stress happened after the beginning of pod setting and delayed when it occurred during the flower bud setting and flowering. Crop growth rate and net assimilation rate were reduced during a period of high precipitation, high cloudiness and low air temperature (Sept. 1 to 24). They also decreased together with leaf area index under water deficit, from the flower bud setting up to beginning of grain filling. Water deficit conditions caused reproductive organs abscision, lower leaf enlargement, and lower crop growth. This behavior was more evident in plants less developed. The specific leaf area was higher in rain periods with low solar radiation and high air humidity.