| Resumo: |
In Cauquenes (35º58' S lat., 72º17' W long.), VII Region, Chile, in a granitic soil, the productivity and persistence of six mixtures with different percentages of annual legumes were evaluated: M1 Trifolium subterraneum (Ts); M2: Ts and Medicago polymorpha (Mp); M3: Ts, Mp and Trifolium michelianum (Tb); M4: Ts, Mp, Tb and Ornithopus compressus (Op); M5: Ts, Mp, Tb, Op and Biserrula pelecinus (Bp) and M6: 20% of each species. The replacement of 50% of the initial seeding rate of Ts by other legumes reduced the population of Ts, particularly in the second and third year. The higher seed production of Mp in mixtures of two or more species in the first two years contributed to the great regeneration of Mp in the third year (1,000-2,000 seedlings m-2 of Mp vs. 100-240 seedlings m-2 of Ts). As a consequence, specific contribution and biomass production of Mp in mixtures (M2-M6) were higher than Ts in the second and third year. The specific contribution of Tb in the mixtures was low (between 4.3 to 17%) in the three years; and that of Op and Bp was almost null in all years. Total aerial biomass fluctuated between 1,673 to 2,020 (P ≥ 0,05) and 3,520 to 4,395 (P ≥ 0,05) kg DM ha-1 in the first and second year, respectively. In the third year, the mixtures with two and five species (M2: 5,838; M5: 5,643 and M6: 5,678 kg DM ha-1) exceeded (P ≤ 0,05) the treatment with Ts only (3,905 kg DM ha-1).
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