Análise de crescimento, fenologia e acumulação de nutrientes de quatro genótipos de bananeira no estado do Rio de Janeiro

Abstract

This work had the objective of to analyze the development pattern and the nutrient accumulation of four genotypes of banana, with micropropagated plantlets, in the conditions of the State of Rio de Janeiro. An experiment was driven in the Department of Fitotecnia of UFRRJ, in Planossolo, in a randomized blocks design with four treatments and four repetitions of 45 plants for plot, in the spacing of 3x2 m. Four genotypes of the banana were evaluated: Thap Maeo (AAB), FHIA-18 (AAAB), SH3640 (AAAB) and Prata Anã (AAB). Only the mother plant was driven per hole, being eliminated the whole sucker. In the first stage, leaves of the four genotypes were sampled eight weeks after transplant (WAT), to determine the correction factor to estimate the leaf area from the length and width of foliar limbo. The angular coefficients of the regression revealed that there are significant differences among genotypes, indicating that in the determination of the leaf area of banana tree by ruler, the factor of correction of 0.79 should be used for cultivar SH 3640, FHIA 18 and Thap Maeo, and 0.83 for Prata Anã. The second stage, the temperature and the precipitation arise as the climate factors more related to the rate of leaf emission of the four genotypes.. The genotype Thap Maeo presented larger vegetative cycle (366 days) and total (468 days) and larger plant height (3.0 m) that the other genotypes. The genotypes didn't present differences in the reproductive cycle and in the diameter of plants. The genotype Fhia 18 presented the largest total mass of fruits for plant. The genotype Thap Maeo presented larger medium number of bunches for bunch, the largest of number of fruits for bunch, the largest relationship pulp-peel, however the smallest fruit size. The genotype SH 3640, although presented fruits of greatest weight and size, presented the smallest number of fruits for bunch and the pulp-peel ratio. In the third stage, to quantify the time variation of plant biomass and nutrient accumulation, one plant was sampled per plot on 8 harvests spaced 8 weeks, when the leaf area measured, and the mass and concentrations of N, P, K, Ca, Mg measured in each plant portion. The growth rates and of nutrient accumulation were measured through the functional plant growth analysis. The mass of rhizomes and stems increased up to 48 WAT and stabilized at 56 WAT. The leaf area, and the mass of active leaves and petioles increased up to 40 WAT and stabilizing in the last three harvests. The net assimilation rate increased between 8 and 24 WAT, and declined mainly after 32 SAT. The rates of nutrient accumulation presented the same pattern regarding with the time of maximal accumulation, varying from 30 to 33 WAT. From the total of nutrients accumulated by the banana plant, the bunch exported after fruit harvest 50% of N, 38% of P, 60% of K, 11% of Ca and 14% of Mg. The total amount of nutrient accumulated, in kg per ha, was 54.5 of N, 14.4 of P, 131.5 of K, 62,5 of Ca and 53 of Mg. .