Indicators of the nitrogen nutritional status of sugarcane submitted to nitrogen rates

Abstract

Diagnosis of the nutritional status of sugarcane is an important complementary tool for management of fertilization. The objective of this study was to evaluate nitrogen nutritional status of sugarcane submitted to nitrogen rates by conventional method and alternatives indicators. The experiment was conducted in a greenhouse with the IACSP95 5000 cultivar, grown in 20 L pots containing sand and vermiculite. The treatments consisted of six nitrogen rates (0, 5, 10, 20, 40, 80 mg dm^-3 of N) using urea as a source. From ten to fourteen days after fertilization, nine productive, nutritional and physiological parameters were evaluated and correlated (shoot dry weight, root dry weight, N content in leaves, total shoot N content, total shoot N accumulation, nitrate content in leaves, NR activity, chlorophyll index in type 0 leaf and chlorophyll index in type +1 leaf). All nutritional, physiological and productive indicators, with the exception of the root biomass, were affected by the variation in the nitrogen supply. There was a high correlation between nitrate reductase enzyme activity and chlorophyll content with leaf N content, suggesting a high potential to indicate the nutritional status of sugarcane.