Early growth of Brazilian tree Dimorphandra wilsonii is also threatened by African grass Urochloa decumbens

[摘要] The conversion of the Brazilian savannas for pastures and agricultural use has caused the species Dimorphandra wilsonii (Fabaceae-Caesalpinioideae) to become isolated and restricted to areas occupied by African grasses of Urochloa sp. This highly endangered tree species was cultivated in the presence of Bradyhizobium japonicum (symbiont 1), Glomus etunicatum (symbiont 2), and Urochloa decumbens in low nitrogen (N) availability in order to evaluate its growth in these experimental conditions. Even though the nodulation and mycorrhization was of low occurrence, the inoculated plants with symbionts had the greatest nitrogen and chlorophyll content, photosynthetic radiation use efficiency, and biomass accumulation in relation to the plants which had not been inoculated and/or cultivated in the presence of U. decumbens . The results suggest effective N 2 fixation, independent of the localization of bacteria, whether in the root tissue interior or free in the rhizosphere. Therefore, the presence of N 2 -fixing bacteria can benefit the early growth of D. wilsonii , whereas the occurrence and aggressive persistence of U. decumbens can limit this development, increasing the threat of extinction of this species in their habitat.

[学科分类] 纳米科学和纳米技术

[关键词] cerrado;conservation;photosynthesis;biological fixation