Características químicas dos solos e colonização radicular por fungos micorrízicos arbusculares em plantas introduzidas em clareiras da Província Petrolífera de Urucu, Amazonas

Abstract

The majority of Amazonian upland soils is considered to be of low fertility and high aluminum saturation. This situation Is found In the Petroliferous Province of the Urucu River In Coari/AM, where bare places and deposite had been opened for the exploration of petroieum and natural gas. To revert this process, they are being reforested with native and exotic tree species. Beyond low the fertility, the elimination of the soil superficial horizon resuits in low potential of beneficiai microorganisms inocuium for the plants, as the arbuscular mycorrhizai fungi (AMF), which are important for the plant growth and survival, by means of the increase of mineral nutriente and water absorption. The present study had as objective to evaluate the presence and rate of these fungi in the plants roots of the bare places and deposite of the Province of Urucu. Soils, roots and plant leaves samples of 36 forest species in 22 bare places or deposite had been collected: IMT4, LUC (36H and 34H), RUC (2, 03/06/13, 7, 8, 26, 35, 41 e 43H) Bare places (2, 12, 18/22 and 29) and Deposit (23, 25, 44, 77, 81, 83 and 87) in the periods of April, July and November of 2003, September and November of 2004 and July of 2005 for chemical analyses of soils and plants and presence of AMF in the roots. Soils showed to be highly acid, with low K, Ca and Mg contente and high of P and Al. The Fe contente had been satisfactory, while that of the Zn and Mn had been low. The root colonization by AMF varied between 0% 46%. The species with the highest rate of fungi root colonization belong to the family of the Myristicaceae (24%), while the species of the Polygonaceae family did not present this association. During the rainy season a bigger presence of vesicles was observed, while at the dry season, hyphae predominated. The accumulation of macro and micronutrients (Ca, Mg, K, P, Fe, Zn, Mn) in the plant leaves varied among the evaluated species, without presenting relationship with the root colonization by AMF. Thus, the AMF littie or no contribution is giving for a better plant nutrition at the bare places and deposits of Urucu.