BIOLOGICAL RESPONSEVINESS OF BEANS UNDER DIFFERENT SOIL WATER REGIMES AT PROTECTED ENVIRONMENT CONDITIONS IN SOUTHERN BRAZIL

Abstract

Climatic conditions and soil water requirement notably impinge upon agriculture in such a way as to galvanize scientists to come up with advanced research in order to assure a more sustainable production at a given site. Under protected environmental conditions water is the main factor to be controlled aiming at maximization of yield and grade of agricultural products. The productive potential of a crop is extremely conditioned by the local atmospheric conditions along with requirements for water and nutrients in the soil. The aim of the current work was to scrutinize the effect of soil water status on the ecophysiological parameters and yield components of two cultivars of beans (Phaseolus vulgaris L.) under tropical climatic conditions. The experiment was carried out in March of 2016 at a greenhouse belonging to the Agronomic Institute of Paraná (Ponta Grossa, PR, Brazil) with beans. The experimental design taken into account herein was a completely randomized design at a factorial scheme with six replications for yield components and four replications for crop ecophysiological parameters. For such a crop, yield components of two genotypes under the influence of four levels of soil humidity were assessed for agronomical purposes. Soil humidity within the stipulated levels at this trial was monitored by means of a Time Domain Reflectometer – TDR. The ecophysiological parameters were analyzed at four distinct times through a LICOR Infrared Gas Analyzer (IRGA), model 6400-XT. By means of such an equipment net photosynthesis, stomachic conductance, transpiration, and photosynthetic water use efficiency were evaluated. Number of pods per plant, grain mass per plant and yield were to be affected linearly as a function of soil water status. A thousand grain mass and transpiration rates for the cultivar Tuiuiú were higher than those related to the cultivar Campos Gerais, regardless of soil water conditions. A part from transpiration rates, all other ecophysiological parameters did not detect effect of the studied treatments on the biological responsiveness of the crop