Fixação biológica de nitrogênio em soqueira de cana-de-açúcar com Azospirillum brasilense e na compatibilidade com agroquímicos.

Abstract

Biological nitrogen fixation by bacteria, as Azospirillum brasilense, in sugarcane crop, has been presented as an economic and environmental sustainable alternative, as it can reduce the need of nitrogenous fertilizers without yield loss. The objective of this study was to verify the response for spraying Azospirillum brasilense with or without nitrogen fertilization in ratoon cane. The experiment was established in two producing units located in Tupaciguara-MG and Guaíra-SP, in ratoon areas of RB855156 and RB966928 varieties, respectively. The experimental design was completely randomized block with eight treatments and four replications with the combined applications of 60 kg ha-1 N with different doses (0.2, 0.4, 0.6 and 0.8 L ha-1) of solution containing the bacteria, only N doses (60 and 120 kg ha-1), only bacteria solution dose (0.8 L ha-1) and the control without N and the bacteria application. It was evaluated the amount of tillers 60, 90 and 120 days after application, foliar N content and N extracted by the plant, cane and sugar yield and quality parameters as TRS. Foliar bacteria application did not affected foliar N content, TRS, total soluble solids, fiber and sucrose content, in the two varieties studied. The variety RB966928 was responsive to the leaf spraying of the product containing Azospirillum brasilense obtaining a significantly increase in the cane and sugar yield in relation to the control. The Azospirillum brasilense leaf spraying in sugarcane ratoon presents potential of use, indicating to be an alternative of use to reduce cost of nitrogen fertilization.