Fungos micorrízicos arbusculares no crescimento de mudas de pinhão manso (Jatropha curcas L.)

• Autor(a) principal: Carvalho, André Mundstock Xavier de
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5298
• topic: Fungos micorrízicos arbusculares; Fósforo; Nutrientes; Arbuscular mycorrhizal fungi; Phosphorus; Nutrients; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO::MICROBIOLOGIA E BIOQUIMICA DO SOLO

Physic nut is a shrub of the Euphorbiaceae family that can be used as raw material for the production of biodiesel. Its rusticity, tolerance to draught, and low nutritional demand, among other traits, may be related to the mycorrhizal dependency of this plant. Thus, the objective of this work was to evaluate the occurrence and the abundance of arbuscular mycorrhizal fungi (AMFs) in physic nut plantations and to evaluate the effect of soil P levels on the nutrition and growth of mycorrhizal physic nut seedlings. Soil and root samplings were done in a nursery and in seven plantation sites located in the municipalities of Viçosa and Canaã, Minas Gerais State, Brazil. The chemical characteristics of the soils in the plantation sites did not suppress mycorrhizal colonization, always higher than 70 %, although in some cases, significant negative correlations were observed between soil fertility and root colonization and spore numbers. Spore density varied from 8.5 to 47.4 spores per gram of dry soil. Nutrition and growth of mycorrhizal physic nut seedlings were evaluated in the greenhouse under different P levels. Seedling growth responded positively to phosphate fertilization and to mycorrhizal colonization. In general, AMF inoculation favored the total nutrient content and the leaf concentrations of N, P, K, Zn, and Fe. The inoculated plants showed mycorrhizal colonization percentages varying from 41 to 96 % and higher photosynthetic and transpiration rates than the non-inoculated control plants, even in the highest P level tested. The nutrient levels in the leaves indicated that the nature of the benefits brought about by AMF inoculation is due to a better plant nutrition. These results indicate that phosphate fertilization does not inhibit mycorrhizal colonization, even at 600 mg kg-1, suggesting that physic nut plants show a considerable level of dependency on the mycorrhizal association.