Produção e índices tecnológicos da cana-de-açúcar sob níveis de salinidade em dois ciclos de cultivo.

Abstract

Production and technological indices of sugarcane under salinity levels in two crop cycles. The sugarcane cultivation can be a viable alternative for deployment in areas with salinity problems, need for such research to this end. Therefore, the aim of this study was to evaluate the production parameters and technological indexes of sugarcane irrigated with salted water during the dry season, the first and second crop cycles. The experiment was conducted in the experimental design of randomized blocks in a factorial 2 x 5 (two cultivars of sugarcane x five levels of salinity), resulting in ten treatments and four replications in 40 lysimeters, whose share It consisted of four copse by lysimeters. The two cultivars of sugarcane were SP81-3250 and RB92579. The five levels of irrigation water salinity were: 0.9; 1.6; 2.6; 3.6 and 4.6 dS m-1 expressed in terms of electrical conductivity of irrigation water. Salinity levels were obtained with the addition of NaCl, CaCl2 and MgCl2 city water supply system, in the ratio 7: 2: 1, respectively. The evaluations consisted of growth variables (APT, DCT) production component (PCT) and technological indexes (ºBrix, polarized sucrose, purity, fiber, pol cane corrected and total recoverable sugars). The RB92579 and SP81-3250 cultivars differed in plant height per plant (APT) after 68 and 107 days after budding (DAB) and diameter of stem per plant (DCT) to 182 DAB. The increase in saline irrigation water up to 4.6 dS m-1 damaged the APT committed to 68, 107, 147, 182 and 296 DAB; but DCT obtained better value to 107 and 147 DAB with 0.9 dS m-1. The interaction between the factors "Cultivating x Salinity" was not significant for any variable analyzed. The use of irrigation with water levels up to 4.6 dS m-1, without prejudice to the weight of stems per plant (PCT) in RB92579 and SP81-3250 cultivars in the second crop cycle. °Brix, pol, fiber, PCC and ATR in the first cycle are the technological indexes of sugarcane changed by cultivating factor where RB92579 stands. In the second cycle, no technological index showed significant differentiation.