Gas exchange, growth, and antioxidant activity in sugarcane under biological nitrogen fixation

Abstract

The aim of this study was to characterize the key physiological aspects of three sugarcane cultivars (RB92579, RB867515 and RB872552) under biological nitrogen fixation (BNF). Plants were generated in tubes containing aseptic substrates and these plants were transferred to pots containing washed sand, but watered with a mineral fertilizer, and inoculated with a mixture of five diazotrophic bacteria three times at seven-day intervals. Under BNF, all of the cultivars contained half of their total leaf nitrogen content and 50% less shoot dry mass. The leaves of plants under BNF showed approximately 65% less of the total protein content (TP). The gas-exchange control plants had twice the CO2 assimilation rates than the BNF plants. The activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX) was increased in all cultivars under BNF when compared with the control; thus, the content of hydrogen peroxide (H2O2) was also increased in these plants. The results of this study indicate that after acclimatization, the inoculation of young plants from tissue culture with diazotrophic bacteria could supply approximately 50% of their nitrogen requirement. © 2012 Springer Science+Business Media Dordrecht.