PRODUCTIVE PERFORMANCE OF GRASS-LEGUME ASSOCIATIONS UNDER GRAZING CONDITIONS

Abstract

With the aim to maximize dry matter (DM) yield, several associations of two grasses (orchard grass, Dactylis glomerata, and perennial ryegrass, Lolium perenne), and one legume (white clover, Trifolium repens) were studied. Five proportions (%) of white clover, orchard grass and perennial ryegrass were utilized: 40:30:30; 40:0:60; 40:60:0; 40:20:40 and 40:40:20, and allocated in 20 experimental units, under a randomized block design with four replications. The measured variables were dry matter yield, growth rate, plant height, and botanical composition. Swards were grazed by sheep Suffolk x Dorset, every four weeks in spring-summer and every six weeks in autumn-winter. The 40:20:40 association showed the highest DM yield, wich was 52 % higher than that of 40:60:0 with the lowest value (P ≤ 0.05). In all the associations, the highest DM yield was observed in spring-summer and the lowest in autumn-winter, with 65 and 35 % of the annual yield. On average, white clover, orchard grass and perennial ryegrass contributed 51, 31 and 17 % of the total DM yield, respectively. The best associations were 40:20:40 and 40:30:30. From the mixture analysis, the ideal proportion that maximizes DM yield was 40, 23, and 37 % of white clover, orchard grass and perennial ryegrass, respectively. These values were obtained using the following regression equation: DM yield (kg ha^-1) = 11906 (orchard grass proportion) + 14913 (perennial ryegrass proportion) + 12770 (orchard grass proportion) x (perennial ryegrass proportion).