EVAPOTRANSPIRATION, DUAL CROP COEFFICIENT AND OFF-SEASON MAIZE YIELD IN A SINGLE AND AN INTERCROPPING SYSTEM

Abstract

This work aims to evaluate the influence of different sowing times of crotalaria in an intercropping system with off-season maize on evapotranspiration, dual Kc values and the productive characteristics of maize and crotalaria. The experiment was carried out in the experimental field of the State University of Mato Grosso (UNEMAT) in Tangará da Serra, Mato Grosso, Brazil, with six treatments: single crop maize (MS); sowing of crotalaria simultaneous with maize (MCS); sowing of crotalaria with maize in the VE stage (MCVE); sowing of crotalaria with maize in the V2 stage (MCV2); sowing of crotalaria with maize in the V4 stage (MCV4); sowing of crotalaria with maize in the V6 stage (MCV6). The crop evapotranspiration (ETc) was determined through the mass variation of the weighing lysimeters and converted into mm d^-1. The methodology used was the dual Kc of FAO bulletin 56, dividing the dual crop coefficient (dual Kc) into the soil water evaporation coefficient (Ke) and basal crop coefficient (Kcb). The phenological phases of the maize crop were determined as recommended by the FAO: initial (I), development (II), intermediate (III) and final (IV). At the end of the crop cycle, the productive characteristics of maize and crotalaria were evaluated. The soil water evaporation for single maize was 253.47 mm, 3.25% more than the average of the intercropping treatments. The ETc throughout the cycle was 497.42, 477.19, 481.95, 481.95, 480.76 and 486.71 mm and the average dual Kc obtained was 1.18, 1.11, 1, 13, 1.13, 1.11 and 1.14 for treatments MS, MCS, MCVE, MCV2, MCV4 and MCV6, respectively. The intercropped maize can be cultivated in any evaluated sowing time of crotalaria, but the sowing of crotalaria simultaneously with maize and with maize in stages VE, V2 and V4 are the most indicated.