Relationship of nitrogen use and nitrate reductase activity by sugarcane cultivars

Abstract

Intrinsic genetic potential of each cultivar of sugarcane may determine the absorption intensity and nitrogen assimilation. It is possible to occur a lower expression of the productive potential by limitations related to low nitrate reductase (NR) activity, since this enzyme is "key" of the N metabolism. The objectives were to compare cultivars of sugarcane as the level of NR activity and its relationship to productive and nutritional variables. The experiment was conducted under condition of a greenhouse, where were grown ten sugarcane cultivars in pots of 4 dm3, filled with sand and vermiculite plus nutrients as indicated for the crop. The variables evaluated were: plant height, NR activity, dry matter (shoot and roots), N content and N accumulation and N uptake and utilization efficiency, moreover, the correlation between the variables was evaluated. The results showed that NR activity varies with the cultivar and further, that NR activity in sugarcane leaves does not correlate with the N uptake efficiency, but is positively correlated with N content and negatively with N utilization efficiency. The NR activity is not a good physiological parameter to discriminate N efficient use sugarcane genotypes

Keywords

• saccharum spp., nitrogen fertilization, nitrogen use efficiency, genotypic variation