Physiological Effect of Kinetin on the Photosynthetic Apparatus and Antioxidant Enzymes Activities During Production of Anthurium

The results observed in the literature raise the hypothesis according to which cytokinin plays important roles in photosynthetic metabolisms and antioxidant enzymes. Thus, the study aimed to evaluate the effect of foliar application of the isolated cytokinin kinetin at the production cycle, seeking to analyze its effects on enzyme activity and photosynthetic parameters. The plants treated with CK presented reduction of leaf CO2 assimilation rate (P-n) and stomatal conductance (G(s)), while that transpiration rate (T-r) was unaffected. The internal CO2 concentrations decreased with the increase in cytokinin levels, but were maintained under CK 50 mg.L-1. The plants treated with CK 75 mg.L-1 was verified higher carboxylation efficiency (P-n/C-i), which was associated to values of CO2 assimilation and transpiration unaltered. Apparent electron transport rate showed variations in the concentration of 25 mgL(-1). Considering the study of enzyme activity, on the other hand, it cannot be stated that kinetin has an effective action in delaying oxidative damage. It presents mixed results, since an efficiency in the application of cytokinin was not observed, presenting induction levels of ascorbate peroxidase activity. Thus, further research is needed to determine more precisely the effects of kinetin on gas exchange and antioxidant enzymes in anthurium plants.