The influence of source of nitrogen and aluminium on the growth of florest trees
Al, N, nitrogen fixation
The growing demand for technology to exploit the potential of native forest species requires information on the silviculture of native species in the various fields of knowledge, including mineral nutrition. Among the elements essential nitrogen (N) is one of the most required by plants and Al causes phytotoxicity. Biological nitrogen fixation (BNF) is an important resource for N acquisition, occurring through the interaction between a plant host, mainly leguminous plants, with bacteria (rhizobia). Some tree species take more than 20 days to form the nodule, in this case, for good initial development a nitrogen fertilization may be recommended. The different source of N can actively change the pH of the rhizosphere, with acidity or alkalinity generation, a process that is directly influenced by the unbalanced absorption of ions: NH4 + acidifies, NO3 - increases pH. The plant using N2 also acidifies the rhizosphere. The initial process of growth and development of legumes can be influenced by nitrogen sources and it is not yet clear how this occurs, especially in forest species. In addition to nitrogen, in tropical soils, the presence of aluminum at toxic levels can affect growth. The toxicity caused by Al + 3 causes delayed nodulation, reduction in nodule number and dry mass of nodules. The objective of this work is to study the interaction between N and Al3 + in the growth and development of seedlings and to verify the nodulation in tree legumes.