Nitrate Reductase Activity, Productivity and Technological Quality of Sugarcane Under Molybdenum and Nitrogen Fertilization

The low uptake of nitrogen (N) by sugarcane causes reduction in productivity and technological quality of sugarcane. Molybdenum (Mo) is a nutrient directly related to the assimilation of N. The objective of this study was to evaluate the effect of Mo and N on nitrate reductase activity (NRA), productivity and technological quality of sugarcane in ratoon cane cycle under Mo and N fertilization. A field experiment was carried out using the variety SP 933,094, subjected to four doses of Mo (0, 100, 200 and 400 g ha(-1)) and three doses of N (0, 60 and 120 kg ha(-1)). Biometric growth variables, NRA, productivity and technological quality of the sugarcane were evaluated. NRA increased with the application of Mo doses at all N levels, with a maximum of 400 g ha(-1). The increase in the agricultural productivity was higher with N application of 120 kg ha(-1), equal to 17 Mg ha(-1) with Mo application of 206 g ha(-1). The maximum increments in sugar productivity caused by Mo application were 12%, 27% and 18%, respectively, with N doses of 0, 60 and 120 kg ha(-1). The combined doses of 120 kg ha(-1) of N and 200 g ha(-1) of Mo promoted greater agricultural productivity and sugar productivity. Our results suggest that Mo did not promote reduction in the use of N, but showed that nitrogen fertilization was stimulated by the use of Mo, by the increase in NRA, increasing the productivity and technological quality of sugarcane.