Morfogênese de Trachypogon plumosus sob calagem, adubação e idades de rebrota

Abstract

In Roraima´s savannas, Trachypogon plumosus is the predominant grass in plain and flood-proof areas and presents greatest forage potential for ruminant feed. Morphogenetic characterization is a very useful tool to determine the potential productivity of forage grasses and their physiological basis, allowing the proposition of management practices more efficient and sustainable. To evaluate the effects of soil fertility correction levels (control, liming, fertilization and liming + fertilization) and regrowth ages (21, 28, 35, 42, 49, 56, 63, 70, 77 and 84 days) on growth dynamic, forage yield and morphogenetic and structural characteristics of Trachypogon plumosus. The experimental design was in randomized blocks with three replicates and treatments arranged in a factorial 4 x 10. Dry matter (DM) yields, tiller population density (TPD), number of live leaves (NLL), leaf blade length (LBL), leaf area index (LAI), leaf elongation rate (LER) and leaf senescence rate (LSR) increased consistently (p<0.05) with regrowth age, while the leaf appearance rate (LApR) was inversely proportional to regrowth age. The grass showed high responsivity to the soil fertility improvement. Liming + fertilization or fertilization alone provided higher (p<0.05) DM yields (1934 and 1661 kg ha-1), NLL (4.93 and 4.85 leaf tiller-1), LApR (0.119 and 0.109 leaf day-1 tiller-1), LER (2.14 and 1.80 cm day-1 tiller-1), LBL (18,5 and 16,1 cm), LAI (2.42 and 2.14), TPD (570 and 534 tillers m-2) and LSR (0,196 and 0,178 cm day-1 tiller-1). To maximize the forage use efficiency and to prevent larges losses relative to senescence and leaves death, during rainy season, it is recommended at regrowth intervals of 56 to 63 days for liming + fertilized and fertilized pastures and, 63 to 70 days for control or liming pastures.