Atributos produtivos e morfológicos do Megathyrsus maximus cv. mombaça sob irrigação

Abstract

In Brazil, approximately 180 to 200 million hectares are occupied by pastureland, with our country leading in commercial livestock production worldwide. About 90% of the livestock are exclusively grass-fed. Given this scenario, it is essential to seek greater productivity; however, irregular rainfall distribution and low temperatures in winter typically limit forage productivity. Irrigation emerges as a means to mitigate these climatic adversities. Thus, this research aims to evaluate the productive characteristics (productivity, morphological composition, and seasonal effects) of the Megathyrsus maximus cv. Mombaça grass, with and without irrigation, over a period of two years. The experiment was conducted at the Irrigation Experimental Area of the Federal University of Grande Dourados. The experimental design adopted was randomized blocks with split plots, with four replications, each plot established with and without irrigation. Sampling occurred every 28 days, evaluating productivity, percentage of dead material, leaf/stem ratio, crude protein, and neutral detergent fiber (NDF). Mombaça grass showed higher productivity with irrigation, with values for Year 1 and Year 2 of 49,312.3 and 64,177.5 kg ha 1 yr-1, respectively. The lowest percentage of dead material was observed in Year 2 with irrigation, reaching 3.18% (spring) and 7.88% (summer). In Year 2, with irrigation, the highest average height found was 86.5 cm (spring), a value associated with increased rainfall during that season. The leaf/stem ratio (LSR) recorded the highest value of 5.29 (spring) with irrigation and 4.71 (autumn) without irrigation. For crude protein and neutral detergent fiber (NDF), the values were 10.11% and 9.79% for irrigated and non-irrigated, respectively. As for NDF values, 47.64% and 47.37% were observed for irrigated and non-irrigated, respectively. Mombaça grass showed significant variations in productivity throughout the seasons, with lower forage availability during autumn/winter compared to spring/summer. Although irrigation mitigated the effects of seasonality, it was not possible to equalize forage production capacity in different seasons of the year. Irrigation practice yielded better results, particularly in higher dry matter productivity and morphological composition. Crude protein and neutral detergent fiber levels did not differ with irrigation use.