Rendimento de grãos de pinhão-manso submetido a diferentes níveis de irrigação e adubação potássica

Abstract

Among the various oil plant species, the Jatropha stands out because of the possibility of achieving high levels of productivity and quality of oil. Although this productive potential, there are many uncertainties regarding the agronomic aspects that interfere in the production, making it impossible a secure fi nancial investment. In this sense, this work aim was to evaluate the second year of jatropha grain production, under different irrigation and potassium levels, in Lavras, south of Minas Gerais State, Brazil. The experimental design was randomized blocks, in spit plot design, with four replicates. It was applied four irrigation levels based on the water balance between the class A pan evaporation (ECA) and rain depths – L0 (rainfed), L40, L80 and L120 (40, 80 and 120% of the water balance respectively), and four potassium levels: K30, K60, K90 and K120 (30, 60, 90 and 120 kg ha-1 of potassium, respectively), applied by drip fertigation. The irrigation levels showed significant effect in productivity and water use efficiency for the second growing year of jatropha. The potassium dosage treatments do not affect significantly the productivity, however influenced the water use efficiency, reaching maximum value using 120 kg ha-1 of potassium.