WATER REQUIREMENTS OF Dipteryx alata VOGEL SEEDLINGS AT DIFFERENT SOLAR RADIATION LEVELS IN CERRADO-AMAZON TRANSITION

Abstract

Background. Water and energy availability are factors that determine the maintenance, growth and development of plants and, consequently, affect its productivity. knowledge what water requirements of forest species during the initial growth stage under different energy levels are essential for technical and economic planning and the proper management of irrigation in forest nurseries, aiming at the production of healthy seedlings. Objective. The evapotranspiration potential (ETc) and crop coefficients (Kc) of baru plants (Dipteryx alata Vogel) were set at the early plant development stage, at increasing shading (black polyolefin screens) and spectral solar radiation levels (colored polyolefin screens), in order to subsidize irrigation and management projects focused on forest nurseries. Methodology. The experiment was conducted in the Center-Northern region of Mato Grosso State, during the dry season (from June to October 2017), for 125 days. ETc was measured through capillary lysimeters, whereas reference evapotranspiration (ETo) was set through the FAO-56 Penman-Monteith equation - Kc values were defined through the ETc/ETo ratio. Destructive growth analysis was performed 125 days after transplantation in order to determine the morphometric variables of the plants. Results. Increased shading levels decreased ETc, Kc and seedling stem diameter, besides increasing the leaf area. The herein adopted quantitative and spectral shading levels did not affect growth (in height) and dry mass accumulation in different D. alata seedling partitions. Implications. The results obtained allow defining improvements in the management of irrigation of forest nurseries. The adoption of irrigations systems with design errors and/or with water requirements inadequate for the production of forest seedlings may lead to yields lower than the genetic potential of the species, favor the establishment of diseases increased the consumption of nutrients and water. Conclusion.The production of D. alata seedlings depends on the cost-benefit ratio of shading screens and local water availability - production in full sun condition is recommended whenever water is not a limiting factor.