Abstract
Potato single nodes were subcultured onto fresh MS medium gelled with 0, 1 and 2 g/l of agar + 40, 50 or 60 g/l of commercial com and potato starch (CS or PS, respectively). After 4 weeks of culture, the pH of medium supplemented with 50 or 60 g/l of CS or 60 g/l of PS was significantly decreased to 3.91 - 4.00. This reduction coincided with a significant increment in electric conductivity (EC) which was 172 - 214 kmhos/cm super(-1) for media containing 50 or 60 g/l of CS, or 60 g/l of PS. Com and potato starch had no significant effect in plantlet height nevertheless, they significantly increased the number of shoots/explant over the control treatment (2.5) which had 7 g/l of agar. The highest number of shoots/explant (6.8) was achieved in medium with 50 or 60 g/l of PS + 1 g/l of agar. Plantlets developed on media with 40 g/l of CS or PS had higher shoot fresh and dry weight (p < 0.5) compared to those in the control one. Media with 50, 60 g/l of PS or 60 g/l of CS and 50 g/l of CS + agar at 1 g/l significantly enhanced the percentage of dry weight. Moreover, 92 - 98% of plantlets were acclimatized to the greenhouse conditions regardless the type of gelling agent. The results suggest that the combination of agar and PS or CS could offer a firm support for plant tissues and could be successfully used for potato micropropagation.