COMPARISON OF EFFECT OF OSMOREGULATORS AND GROWTH INHIBITORS ON in vitro CONSERVATION OF SUGARCANE

In vitro conservation systems are an option for preserving sugarcane germplasm (Saccharum sp.). The objective of this study was to assess the effect of the osmoregulators manitol and sorbitol (0, 15, 30 and 45 g L-1) and the plant growth inhibitors abscisic acid (ABA) and padobutrazol (PAC) (0, 1, 2 and 3 mg L-1) on in vitro growth of sugarcane. The plants used were 2 cm tall in vitro shoots of the variety Mex-69-290 obtained in the multiplication phase. In all cases MS (Murashige and Skoog) medium was used. The experimental design was completely random with 10 explants per treatment. Data were analyzed with an analysis of variance (ANOVA) and means were compared with the Tukey test (p <= 0.05). After 180 d of culture, survival percentage, number and length of the shoots, number of leaves, and number and length of roots were assessed. Analysis of the results showed that an increase in concentrations of osmoreg-ulators produced a decrease in all of the variables assessed. For the inhibitors, the PAC treatments maintained 100 % survival and promoted more shoots per explant. This contrasted with the ABA treatments in which the assessed variables decreased. Reduction in height and presence of axillary shoots observed in treatments with PAC may be of interest for in vitro conservation, and, it is concluded that the use of PAC would be a new option for in vitro conservation of sugarcane germplasm.