Eficiência no uso de nitrogênio por genótipos de algodoeiro arbóreo sob aplicação de fósforo

The efficient production of cotton in soils with low levels of phosphorus (P) require a better understanding of the interference of plant adaptations in relation to P stress, about the absorption, transport and use of other nutrients such as nitrogen (N). Thus, the selection of genotypes efficient in the use of N in low P supply conditions is an effective tool for proper plant development. Hear, was to evaluate the nitrogen use efficiency in Gossypium barbadense L. genotypes grown in an adequate and low phosphorus availability conditions. For that were tested 14 genotypes of pima cotton, grown in two level of P supply: adequate and low level. We evaluated the concentration and accumulation of N, as well as the N efficiency of absorption, transport and use. The genotypes grown under low P supply showed higher leaf N, indicating clear synergistic relationship between N and P. The MT 92 genotype showed a higher capacity to absorb and transport of N in low P supply in the soil conditions. The MT 105 genotype showed higher capacity of conversion N in biomass. The genotypes studied were characterized as a source of genes for adaptation to low P availability for the use of N, are indicated for genetic improvement in the cotton crop (Gossypium hirsutun L).