Grazing resistance mechanisms in alfalfas of different aptitude in the juvenile stage

Abstract

-This study aimed at verifying whether juvenile plants of alfalfa cultivars with different aptitude (grazingtype: Alfagraze and ABT 805; hay-type: Crioula) show morphophysiological differences in order to develop a protocol for early selection for grazing persistence. Two experiments were conducted in a greenhouse, in completely randomized design and three repeplicates. In Experiment 1, plants were evaluated from successive destructive harvests at 60, 90, 120 and 150 days of age. In Experiment 2, plants at 150 days of age were cut to a 10-cm stubble and harvested at 15 and 30 days of regrowth. In Experiment 1, Alfagraze showed the lowest height (19 cm), internode length (1.4 cm) and apical bud accessibility (15.3 cm). Grazing-type cultivars did not differ significantly for subterranean hypocotyl diameter (3.5 mm) on the mean ages, and at 120 days of age they had lower number of leaves (56/ Para estes caracteres a seleção precoce é possível e a Alfagraze pode ser utilizada como testemunha.Palavras-chave: ABT 805, Alfagraze, Crioula, evitamento (escape), tolerância R. Bras.