Some morphogenic and structural characteristics of four forage grasses grown under four soil moisture conditions were assessed. The forage species were: Setaria anceps Stapf., Hemarthria altissima [Poir] Stapf. & Hubbard, Acroceras macrum Stapf. and Brachiaria purpurascens [Raddi] Henr. Soil moisture level was controlled by weighing individual pots and by relative saturation of total porosity (RSTP). A randomized block design with three replications was used. Four plants of each specie were submitted to four soil moisture levels: deficit (50% RSTP)(D), control (100% RSTP) (C), water logging 1 (120% RSTP) (W1) and water logging 2 (150% RSTP) (W2). Three tillers in each plastic pot were used for morphogenic and structural characteristics measurements of the plants: leaf appearance rate (LAR), phyllochron of individual leaves (PHYL), leaf elongation rate (LER), final length of individual leaves (FL), number of expanded leaves (EL) and number of individual green leaves (GL). LER and PHYL in Setariagrass varied linearly and inversely with soil moisture, while others grasses showed quadratic responses. Hemarthriagrass presented the highest LAR under water logged soil condition. FL on day 45 of regrowth followed the same pattern of LAR, with higher values in setariagrass, reaching up to 0.34 m. Hemarthriagrass presented the highest values of FL among the short grasses, in all of the soil moisture condition. Both EL and GL showed significant grasses and soil moisture levels interaction. Hemarthriagrass showed higher values of EL and GL under any moisture level, reaching 12 leaves per stem. The structural differences observed among the studied species may be useful criteria for the selection of grasses according to soil flooding condition throughout the year.
Acroceras; Brachiaria; flooding; Hemarthria; leaf blade; Setaria
