Associações com fungos micorrízicos e bactérias fixadoras de nitrogênio em Allagoptera arenaria (Gomes) O. Kuntze na restinga de Marambaia, RJ

Abstract

The term sandbank, in its phytogeographical sense, designates all the vegetable formations that happens on the coastal quaternary plains current of the last marine regression and that were colonized by the flora and fauna coming from adjacent ecosystems. The sandbanks correspond to an extension of 70% of the Brazilian coast, corresponding to about 1.200 km2 of the state of Rio de Janeiro. The Allagoptera arenaria is a palm tree that has a variable height up to 3 meters, stem of the estipe type, usually undivided and underground. It can be seen from Pernambuco to Paraná, and in the state of Rio de Janeiro it has a widely occurrence, happening on all the sandbanks, from the most preserved to the most impacted. They form dense populations at certain points of the sandy string, characterizing the formation of Palmae bushes on the Marambaia sandbank. The abuscular mycorrhizal fungi (AMF) are obligatory organisms to most of the vascular plants, constituting an exception its absence. Besides, they play an important role in the nutrients cycle in tropical forests. The maximization in the obtaining of nutrients for inoculated plants contributes to the vegetable growth and the increase of your resistance to adverse situations. The FBN stands out as an important alternative to nitrogen fertilizers, and it’s important to know the associations made by this bacterium. Considering the intense destruction that it’s aware of, it is more and more important to know the floristic and the structure of the areas of sandbanks in order to help with the conservation and recovery of degraded areas. This work had the objective of evaluating and quantifying the existence of the association of abuscular mycorrhizal fungi and the fixation of nitrogen bacteria in A. arenaria on the Marambaia Sandbank. Ten samples of the pre and post-beach and five of each experimental area were collected, and they were composed of 200g of soil with roots collected in approximately 2/3 of the projection of copa. The roots were clarified and quantified according to the colonization presence of fungi. The spores were identified and quantified. A. arenaria accomplishes association with (AMF) and the nitrogen fixing bacterium, finding the largest incidence of spores on the pre and post beaches. The roots presented an average rate of colonization of 68,2%, and this factor contributes to confirm the statement above. The bacterium study allows us only to confirm its association to the palm. This research suggests what this palm tree offers to the maintenance and conservation of the sandbank soils, standing up as an excellent option for the selection of seedlings for reforestations.