CARACTERÍSTICA MORFOLÓGICAS E PRODUTIVAS DE DIFERENTES FORRAGEIRAS SOB IRRIGAÇÃO NO NORTE DO TOCANTINS

Abstract

Warm climate conditions all year round, combined with irrigation, adequate management of soil fertility and grazing, can favor the break in the seasonality of tropical forages, increasing the productivity of pastures in the north of the state of Tocantins. The objective of this study was to evaluate the morphometric and productive characteristics of forage cultivars of the genus Megathyrsus under irrigation in Araguatins (TO). The treatments were the cultivars Mombaça, Zuri, MG-12 Paredão, Tamani and PM-175 of the species Megathyrsus maximus. The experimental design used was randomized blocks with 5 treatments and 4 replications, distributed in plots of 11 m2 each (2.75 x 4 m). The evaluation period was from May 2022 to May 2023, totaling 15 to 16 cuts between cultivars. The variables analyzed were: number of cuts (NC), neglect period (PD), tiller density (DP), green mass productivity per cut (PMVC), annual green mass productivity (PMVA), dry matter content ( TMS), dry mass productivity per cut (PMSC), annual dry mass productivity (PMSA), percentage of leaves (PF), percentage of stem (PC), leaf-stalk ratio (F/C), dry mass productivity period (PMSPS), wet season dry mass productivity (PMSPC), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF). There were significant effects for cultivars for all growth and production variables, except for PMVC, and also for cultivar x cutting interaction for ADF and NDF, with PB being affected only for cutting time. The Tamani cultivar stood out with a greater number of tillers and cuttings, shorter regrowth time, higher leaf-to-stalk ratio, however lower annual dry mass productivity due to the significant drop due to excess rainfall. Zuri presented the highest PMSA, along with Mombasa and MG-12. The use of irrigation provides shorter regrowth periods with intervals of 15 to 27 days in the dry season months. Irrigation promoted increases of 16.2 to 55.5% in the dry mass productivity per hectare of cultivars between the dry (irrigated) and rainy periods and contributed with 56.63% of the total annual dry mass production. The studied cultivars have potential for livestock intensification with the use of irrigation in the north of Tocantins, and other factors must be managed.