PEANUT CULTIVARS SUBMITTED TO IRRIGATION LEVELS AND NITROGEN ADUBATION IN TROPICAL CLIMATE

Abstract

ABSTRACT: The objective of this study was to define the best irrigation level in a sprinkler system, submitted to nitrogen doses in covering in the municipality of Tangara da Serra - MT, for two cultivars of peanut (Arachis hypogaea L.). The experiment was carried out in the experimental field of the State University of Mato Grosso (UNEMAT), located geographically in latitude 14°39′S; Longitude 57°25′W, at 440 meters of altitude. The climate is classified as tropical humid megathermal (Aw), with annual average rainfall of 1,830 mm and average temperature of the air 24.4°C. The soil is classified as Dystroferric Red Latosol. The experimental design was in randomized blocks where 4 levels (30, 70, 110 and 150% of the reference evapotranspiration, ET0) were determined. In each level, 0, 30, 60, 90 and 120 Kg ha-1 of nitrogen were applied in two peanut cultivars IAC Tatu ST and IAC Runner 886. Each plot had 24 lines per 12 m length, 4 lines for each dose of N in each level and cultivar with 0.45 m spacing between lines. The irrigation level that provided the highest productivity in the development cycle for both peanut cultivars was 110% of ET0. While the levels of 30 and 70% of the ET0 allowed greater growth in height, but smaller productivities, the 150% ET0 level showed higher yields in the husk, and lower grain yield due to the high germination rate of the grain yet in the plant. For Tatu cultivar, doses of 60 to 90 kg ha-1 of N increase productivity, whereas for Runner cultivar nitrogen fertilization did not affect productivity.