Adubação nitrogenada e molíbdica em cana planta inoculada com bactéria promotora de crescimento

Abstract

Nitrogen fertilizer has low performance in the first cycle of sugarcane (Saccharum spp.). Plant promote-growth bacteria can supply part of nitrogen (N) demanded of plant through biological nitrogen fixation (BNF). Molybdenum (Mo) stimulates BNF, which increases N availability, stalk growth and productivity. This study aimed to evaluate the interaction of molybdenum (0 and 0.4 Kg ha-1) and nitrogen (0 and 60 Kg ha-1) fertilization together with the inoculation of plant promote-growth bacteria Stenotrophomonas sp. (without and with) on BNF and development of varieties RB867515 and RB92579 in the planted cane cycle. The experiment was carried out in randomized block design and in a 2x2x2 factorial scheme, with four replications. The biometric and nutritional variables of sugarcane was evaluated at 140 days after planting (DAP) and at the end of the growth cycle. BNF was quantified by the 15N natural abundance method, using sunflower and sorghum as reference plants. The interaction of factors N, Mo and inoculation did not increase BNF and did not promote the growth of planted cane. Mo increased nitrogen content on leaf +1 and above ground nitrogen content at 140 DAP, and the root biomass of sugarcane. Inoculation does not increase BNF whose average contribution of BNF in the planted cane was 25% regardless of management. Mo increased BNF on RB867515 but not modify it on RB92579. The interaction between nitrogen and inoculation increased biomass production and height of RB92579. Nitrogen fertilization increased height, biomass and stalk production, and the industrial quality of planted cane.