Dimorphandra wilsonii Rizz. is a critically endangered tree species. It has been described for sites of higher soil fertility in the Cerrado Domain. However, it occurs nowadays in isolated areas of low natural fertility. To study species adaptation to oligotrophic conditions, plants were grown in a greenhouse in soils from oligotrophic sites but with different levels of fertility. After soil fertility analysis, the macronutrients (NPK) and lime doses to be used in each treatment were defined, resulting in a combination of two liming levels and three fertilization levels. After 220 days, the treatments that significantly increased seedling growth were the one whose substrate was limed and fertilized with twice the prescribed NPK dosage, and the one with the indicated dosage of NPK but no liming. Liming itself did not promote growth enhancement, but favored increased growth response to increasing levels of nutrient availability. Root nodules were found in all the treatments, and the results led to the conclusion that D. wilsonii nutritional requirements are consistent with its original distribution sites in the Cerrado Domain. It was also possible to highlight nitrogen biological fixation, an unusual feature in Caesalpinioideae, as an adaptive strategy for survival in areas of low nutrient availability.
biological fixation of N2; mineral nutrition; risk of extinction
