PRODUCTIVITY AND NUTRITIVE VALUE OF UROCHLOA BRIZANTHA UNDER WATER SATURATION LEVELS

Resumen

Water availability in the soil can alter the productive and qualitative characteristics of pasture, but the magnitude of the response can be different between cultivars. The aim was to assess the productivity and quality of Urochloa brizantha cultivars subjected to different water saturation levels. The experimental design was in randomized blocks in a 4x5 factorial scheme, with four cultivars, Marandu, Xaraés, Piatã, and Paiaguás, and five levels of water saturation: 20, 40, 60, 80, and 100% of the maximum water retention capacity in the soil, with four replications. The grasses were sown directly into pots. After 30 days, the uniformization cut was carried out, and the water saturation levels were applied. The plant material was collected 40 days after the uniformization cut. The aerial part's dry mass and the grasses' bromatological characteristics were assessed. The data was submitted to analysis of variance and regression analysis for the water saturation levels and Tukey's test for the cultivars at 5% probability. The cultivars Marandu and Xaraés obtained the highest dry mass of the aerial part with average yields of 17.90 and 17.04 g pot^-1, respectively. The maximum contents were obtained at levels of water saturation of 28.21%, 43.09%, 43.44%, and 45.06% with 11.14%, 9.21, 9.84%, and 8.59% crude protein, respectively, for the Marandu, Xaraés, Piatã, and Paiaguás cultivars. Higher water saturation levels lead to a decrease in the crude protein content and an increase in the NDF and ADF contents.