Características produtivas e estruturais de gramíneas forrageiras em função da disponibilidade hídrica

Abstract

The experiment was carried out in a greenhouse at the Department of Agrarian Sciences of the State University of Montes Claros (UNIMONTES), Campus de Janaúba - MG. The experiment was carried out in a randomized block design in a factorial arrangement of 3 x 5, with three forage species (Andropogon gayanus cv. Planaltina; Brachiaria brizantha cv Marandu; Cenchrus ciliaris cv. 131) and five levels of water availability - 20; 40; 60; 80 and 100% of the maximum water retention capacity of the soil. They were used 45 experimental units, 15 treatments and three replicates (blocks). Each experimental plot was constituted in a vessel with a capacity of 5 dm3 of soil. The amount of water was considered in percentage terms equivalent to 100% of humidity in the soil, the other percentages were stipulated based on this principle, thus obtaining the water availability of 20, 40, 60 and 80% FC. Structural aspects were evaluated (plant height, number of tillers, number of inflorescence, yield of green matter and dry matter production). The data referring to the evaluated characteristics were submitted to regression analysis according to the soil moisture conditions and the cultivars, selecting the equations by the coefficient of determination (R²) and the significance of 5% of the coefficients according to the t test. The regression equations were adjusted based on the means of treatments. The variance analysis revealed significance for fodder effects and water availability levels (P<0,05), only for the weight of dead material variable in relation to GM, being that for the variables: plant height, number of tillers, inflorescence, shoot green mass and dry mass, aerial part had an isolated effect of forage factors × levels of water availability. With the increase of water availability, the number of basal tillers, number of aerial tillers, total number of tillers, tillers weight, tiller height and number of inflorescence showed maximum production in the volume of 100% CC and lower production in 20 % Of FC. Regardless of the grasses, the water deficit negatively influences the productive and structural characteristics evaluated.