Effects of water stress on photosynthesis and evapotranspiration in common bean plants.

摘要

The aim of this study was to verify the photosynthesis rate, stomatal conductance, leaf transpiration, evapotranspiration and yielding components of common bean plants (IPR Colibri cultivar) under water stress in two soil types, Dystrophic Red Nitosol and Red Latosol, from the northwest of Parana State. The experiment was carried out in a completely randomized block design with factorial scheme of 4x2x3 corresponding to four levels of water availability (100%, 75%, 50% and 25%) in pots of 20 kg with three replications. Photosynthesis rate, stomatal conductance and leaf transpiration measurements were performed with Infra Red Gas Analyzer (IRGA), and it was observed that they reduced as soil moisture was decreased. From the initial development stage to the pre-lowering the values of evapotranspiration for 100, 75, 50 and 25% of water availability treatments were, respectively, 5.40, 4.94, 4.62 and 3.07 mm d-1 for Latosol and 3.80, 3.40, 2.80 and 2.12 mm d-1 for Nitosol. The photosynthesis rate for 100% of water availability for plants in Latosol and Nitosol were 16.0 and 10.9 micro mol m-2 s-1 and more developed plants presented higher rates and produced more dry mass.