Crescimento de plantas jovens de leguminosas arbóreas em resposta à adubação nitrogenada e inoculação de Rizóbios em Argissolo Vermelho Amarelo e Latossolo Amarelo na Amazônia Central

Abstract

Little one knows on the efficiency of the answer of N2 fixation in legume tree native of the Amazonian when inoculated with specific or homolog rhizobia to demonstrate the use potential of microbial inoculants to stimulate biological technologies in the agricultural production and recovery of soils. The objective of this work was to evaluate the effect of the inoculation with Rhizobia about the growth and biomass distribution in three native legume trees. The selected species were: Inga thibaudiana var. thibaudiana, I. nobilis and Erythrina fusca. Two soils acid of the firm earth they were appraised: yellow oxisol collected under pasture and yellow red ultisol collected in agroforestry systems. The species were sowed in sand and transplanted for bags with 2 soil kg and led in the nursery. In the two soils three forms of supply of N were tested: control treatment (plants not inoculated and without mineral N); plants supplied with 80 kg of N hectare-1; and, plants inoculated with a cocktail of strains of Rhizobia of the INPA collection. Monthly the length of the stem of the plants was evaluated. The crop was made to the 93 days for E. fusca and 165 and 151 days for I. thibaudiana and I. nobilis, being determined the distribution of dry biomass in the leaves, roots, stem and nodules of the plant. The number of nodules was counted and made determinations of leave-N and total-N of the plants. The experimental design was it entirely random, in factorial arrangement 2 x 3 (soils x forms of supply of N), with 9 repetitions. The inoculation with Rhizobia influences the growth, biomass partition, nodulation indicators and absorption of N, having differences in the answer depending on the appraised species. The specificity character or of promiscuity in the selected legume tree is decisive in the answer of the species the inoculation. All the species of legume tree researched adapted better to the soil ultisol compared to the oxisol. It was demonstrated that the employed strains as inoculants in I. thibaudiana var. thibaudiana formed processes of fixation of more efficient N2 than when inoculated in I. nobilis. For E. fusca, considered of behavior non specific as the compatibility with native Rhizobia the practice of the inoculation favored the symbiotic processes in soil oxisol compared to ultisol. It was evidenced that the inoculation technique with Rhizobia has alternative potentiality for supply of nitrogen for the plants, compared the nitrogen fertilization.