Alterações no perfil de frações nitrogenadas em calos de cana-de-açúcar induzidas por deficit hídrico

Abstract

The aim of this work was to evaluate the use of physiological and biochemical parameters, in the characterization of water stress in sugarcane (Sacharum sp.) calluses, cultivars RB 72454 (sensible) and SP 813250 (resistant), differing in drought resistance in the field. The experimental design was completely randomized with a factorial scheme 2x5 [cultivar x concentrations of polyethylene glycol (PEG)], with ten treatments and three replicates. Calluses were submitted to PEG concentrations corresponding to osmotic potentials of 0, -0.3, -0.6, -0.9 and -1.2 MPa, during 120 hours. The variation of relative water content and humidity showed no significant differences between the cultivars. However, it was observed a trend of increase in electrolyte leakage, in the resistant cultivar related to diminishig of the osmotic potential in resistant cultivar. In the sensible cultivar, it was observed a trend of increase in proline, while the resistant one showed decrease, though proline levels were not affected by the water deficit. The amino acid concentrations were bigger in the sensible cultivar. There was a decrease of ammonia in both cultivars. Protein levels were not affected by the PEG. The protein profile evaluated by SDS-PAGE showed no PEG-induced increase in the intensity of bands corresponding to peptides between 14 and 66 kDa. The physiological and biochemical parameters were not related to differential degree of resistance observed in cultivars under field conditions.