Physiological characteristics of grapevine under irrigation and fertilization management

The viticulture in the semiarid region of Brazil stands out in the country due to the expansion of its cultivated area and increased production, especially in the sub-mid São Francisco Valley. However, the supplying of water and an efficient replacement of nutrients to the soil are essential for these crops, due to the intrinsic climatic conditions of this region, such as low rainfall and high evapotranspiration. This study aimed at evaluating the physiological characteristics of ‘Itália’ grapevine (Vitis vinifera L.) under irrigation and fertilization management. The experiment was conducted in a randomized block design, with four replications, in a split-plot arrangement, with four irrigation water depths (0.75, 1.00, 1.25 and 1.5 times the crop coefficient) in the plots and four fertilizer rates (100 %, 75 %, 50 % and 25 %, based on the recommended fertilizer rates for this crop) in the subplots, with addition of organic compounds. The leaf water potential, leaf chlorophyll content, relative water content, photosynthesis, stomatal conductance, internal CO2 partial pressure, leaf temperature and biomass accumulation in the berries were evaluated. The highest leaf chlorophyll contents were found in treatments with fertilizer rates of 70-85 %. Stomatal conductance decreased with the increasing irrigation water depths, thus reducing the internal CO2 partial pressure and increasing the leaf temperature and air vapor pressure deficit. The reduction of 25 % in the conventional fertilization and irrigation of 135 % of the recommended coefficient resulted in the highest average weight of berries. The highest yields were obtained with the lowest irrigation water depths and fertilizer rates of 50-65 %.