Níveis diferentes de nitrogênio, boro e irrigação, avaliando o desenvolvimento e produção para o girassol.

Abstract

Different levels of nitrogen, boron and irrigation, evaluating development and production for sunflower. The sunflower has wide adaptability to soil and climatic conditions in Brazil, with increased tolerance to drought, cold and heat than most species normally grown in the country. Among the micronutrients, boron is essential to the development of higher plants and its deficiency are more common than any other micronutrient. The sunflower is sensitive to low levels of boron in the soil, the less efficient absorption and symptoms of deficiency are frequently observed, especially at the stages of blossoming and ripening of the grains. While nitrogen is the macronutrient most limiting production of sunflower, its excess causes a decrease in the percentage of oil, high doses may increase the incidence of pests and diseases. Due to its importance as a potential source of renewable energy and the lack of information about the system of sunflower production in Northeast Brazil, especially under conditions of semi-arid region of Paraiba, aimed to evaluate the response of sunflower (Helianthus annuus L.) hybrid Helium 253, related to development and production under different levels of nitrogen and boron in different levels of available water. In this sense, such an experiment was conducted in the period from March to June 2012 in a greenhouse at the Federal University of Campina Grande (UFCG) campus and developed in the Laboratory of Soil characterized Irrigation and Salinity - LIS, as the physical aspects and chemical, factorial (4 x 3 x 4), consists of four levels of nitrogen (30, 60, 90, 120 kg ha-1), three doses (2, 3 and 4 kg ha-1) and four levels of water replacement (125%, 100%, 75% and 50% of field capacity (CC)), with three replications, totaling 144 experimental units composed of vessels with a capacity of 30 L. the data were statistically analyzed using -if the SISVAR program - ESAL - SE Brazil, through which the analysis of variance (ANOVA) was performed, applying the F and Tukey tests for comparison of the treatment means and regression analysis to the quantitative factor available water. Were evaluated plant height, the diameter of the rods, the head diameter, leaf area, total biomass and chapters, the number of seeds per chapter and the weight of 1000 seeds, .o volume of water applied and the efficiency of water use, it was found that irrigation with upward and associated with increasing doses of nitrogen fertilization and borácica levels increased all indices of growth and / or development of sunflower plants, as well as their productivity.