Luminosidade e giberelina no crescimento e desenvolvimento do maracujazeiro-azedo (Passiflora edulis Sims f. flavicarpa Degener)

Abstract

The cultivation of passion fruit has had marked growth in Brazil, making the Country one of the leading producer of the crop. However the country is not among the largest exporters since, domestic consumption is greater than production. The objective of this study was to evaluate the effects of lighting condition and the exogenous application of gibberellic acid on growth and development of Passiflora edulis Sims f. flavicarpa Degener. Seedlings were transplanted to pots with a capacity of 5L containing substrate, consisting of a mixture (1:1:1 by volume) of washed coarse sand, chaff of washed coal and dystroferric red latosol. Two experiments were conducted. At first, the plants were grown under light of 130, 280, 650, 750, or 1400 μmol m-2 s-1 for nine months. Light conditions between 600 and 680 μmol m-2 s-1 provided higher length of main stem and lateral highest number of lateral stems, larger plant length, greater number of nodes of the plant, higher fresh and dry weight of plants and earlier issue of the first tendril and the first leaf three-lobed. Condition 650 μmol m-2 s-1anticipated by at least 66 days the flowering compared to other lighting conditions studied. This lighting condition propitiated the largest number of flower buds and the largest number of lateral stems provided with buds. Not been recorded flowering in brightness of 130 μmol m-2 s-1. In the second experiment, plants were grown under light of 650 μmol m-2 s-1 for nine months and subjected to weekly sprays with GA3 at concentrations of 0.0; 1.5; 3.0; 15.0 or 30.0 mg L-1. The concentrations of GA3 influenced most variables except the number of lateral stems, number of main stem nodes to the insertion of the first lateral stem, number of main stem nodes to the insertion of the first tendril and the first leaf threelobes, the number of lateral stems emitted by the plant in the early flowering and number of nodes on the main stem base to the insertion of the first floral bud. Concentration of around 15 mg L-1 caused higher plant length, greater number of nodes of the plant, higher fresh and dry weight of plants. We conclude that the growth and development of P. edulis is subject to the lighting conditions and the best results were observed under 650 μmol m-2 s-1. The use of 30 mg L- 1 GA3 anticipated the issuance of the first tendril and the first leaf three-lobes and produced a greater number of flower buds. Exogenous use of GA3 at concentrations of 30 mg L-1 was more effective in inducing floral that the evocation of Passiflora edulis Sims f. flavicarpa Degener.