DESEMPENHO AGRONÔMICO E ATRIBUTOS TECNOLÓGICOS DE CULTIVARES DE CANA-DE-AÇÚCAR CULTIVADAS SOB DOSES DE ZINCO

Abstract

The sugarcane (Saccharum officinarum L) cultivation is progressively taking on a great importance in the Brazilian territory. Sugarcane yield is influenced by the availability of soil nutrients, so fertilization with micronutrients is important for the crop. Much of the tropical soils have low availability of micronutrients, mainly zinc. The lack of this micronutrient causes serious disturbances to the plant metabolism, generating a reduction in the productivity of temporary and perennial crops. Zinc behaves as an active ingredient in some enzymes and in a structural component of others, as well as in cellular structures. This study aimed to evaluate the zinc doses effect on biometric variables, on culm productivity, and on industrial quality of two sugarcane cultivars, in the first ratoon cane, grown in a Eutrophic Red Latosol of Cerrado (Brazilian Savannah). This study was carried out in the Sugarcane Research Unit, at the Goiano Federal Institute, Ceres Campus, Goiás State (GO), Brazil, in partnership with CRV Industrial. The experimental design was in randomized whole blocks, 4 x 2 factorial scheme, and three replicates. The treatments consisted of four zinc doses (0, 5, 10, and 15 kg ha-1 ) applied to RB92579 and SP801816 sugarcane cultivars. The zinc sulfate (20% Zn, 8.85% S, and 1% K) was applied in the soil. The soil chemical properties were checked on collected samples from the 0 to 25 cm soil deep layer before applying the doses. Zinc sulfate doses were applied in a furrow next to the planting line a few days after the sugarcane first cut. Results found were subjected to analysis of variance, applying the F test, and a regression analysis was made in case of significance for a quantitative variable (zinc dose), and a means comparison test was made for a qualitative variable (varieties). It was found that there was no significant effect of Zn doses for Wet Bagasse Weight (WBW), Purity (PRT), Brix, Apparent Sucrose Content (POL_CAN), Broth Pol (POL_BRO), Reducing Sugar (RS), and Total Reducing Sugar (TRS). There was a significant effect of varieties for the number of buds, in which the variety 1 showed the best result, and of zinc doses for the sugarcane stem diameter, whose dose 2 stood out from the others.