R. Bras. Zootec.01/Apr/2008;37(4):589-95.

Forage Crops

Performance of alfalfa populations under defoliation

Daniela Favero, Simone Meredith Scheffer-Basso, Miguel Dall'Agnol, Daniquelen Seco

DOI: 10.1590/S1516-35982008000400001

This work aimed to evaluate the performance of alfalfa populations in response to defoliation. Two populations of alfalfa cv. Crioula (hay-type) and one population of alfalfa cv. Alfagraze (grazing-type) were evaluated, being selected at seedling stage according to the length of the second internode (EC=1.5 cm; EL=2.5 cm). The trial was performed in pots, between February and August/2005. The populations were harvest at two cutting intensities (2 and 8 cm) and three cutting frequencies (weekly, fortnightly and monthly) during 141 days. There was no difference on shoot dry matter (DM) yield between weekly and fortnightly cuttings; the Crioula-EL, under monthly cuttings was the tallest and had higher amount of stems, surpassing the others. There was similarity between the cultivar Alfagraze and Crioula-SI regarding underground DM biomass. Alfalfa populations responded differently to defoliation management, with a gradual decline on DM yield under more frequent cuttings and a higher survival of plants from Alfagraze compared to Crioula-EC and Crioula-EC. Alfagraze cultivar differed from the Crioula populations, presenting shorter plants, higher proportion of stems originate from the crown and a higher allocation of DM to the underground parts, indicating that these characteristics belong to a grazing-type alfalfa. The length of seedling internodes could be used as a complementary morphological marker to select alfalfa populations more adapted to grazing. In this way, it is possible to obtain populations with DM yield variability and survival.