IFEVA   02662
INSTITUTO DE INVESTIGACIONES FISIOLOGICAS Y ECOLOGICAS VINCULADAS A LA AGRICULTURA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Effects of arbuscular mycorrhiza on the growth of temperate legumes in a subtropical rangeland soil
Autor/es:
HACK CM, PORTA M, TOMEI CE, GRIMOLDI AA
Lugar:
Rosario
Reunión:
Congreso; IX International Grassland Congress; 2011
Institución organizadora:
International Grassland Federation
Resumen:
The predominance of megatermic grasses of Northeastern rangelands of Argentina caused a deficit of winter production and lower forage quality. The incorporation of temperate forage legumes could be a useful practice to improve rangeland condition, but the high phosphorus requirement of these species hinders their establishment in subtropical soils. The symbiosis with arbuscular mycorrhizal fungi (AMF) could increase the ability of plants to uptake phosphorus, and improve the nutritional status of plants. The aim of this study was to evaluate the potential effect of AMF on biomass production and mineral nutrition of two temperate forage legumes in a subtropical rangeland soil under different fertilization conditions. The species used were Melilotus alba and Medicago polymorpha, both annual species with a growing season that ranges from autumn to spring. The substrate used was an Argiudol soil with very low phosphorus and nitrogen levels, from a subtropical rangeland of Chaco Argentino. The experiment was conducted in a greenhouse using a factorial arrangement with a completely randomised design. The main factors were: phosphate fertilization (two levels: unfertilized and fertilized with the equivalent of 100 kg P.ha-1) and inoculation with AMF (two levels: non-inoculated and inoculated with a mixture of Glomus mosseae, G. intraradices and G. hoi). Plant responses were assessed in terms of mycorrhizal colonization, biomass production, phosphorus and nitrogen accumulation. Mycorrhizal inoculation showed contrasting effects on both species in all variables studied. The colonization was higher in M. alba. In this species, when soil phosphorus availability was very low, regardless of the degree of AMF colonization, the presence of mycorrhiza did not reach a significant impact on plant nutrition and biomass production. Under a relatively higher phosphorus provision, the AMF symbiosis promoted biomass production, linked to an improvement in the nitrogen and phosphorus nutrition of the plants. In M. polymorpha, AMF inoculation was negative in terms of nitrogen nutrition when phosphorus was fairly available in the soil and did not produce changes in biomass production and phosphorus accumulation.The response to AMF inoculation is variable according to species and soil phosphorus availability. In subtropical grassland, the effects of AMF inoculation on M. alba production would be positive under fertilization conditions.