In vitro rooting of PR 204/84 rootstock (Prunus persica x P. amygdalus) as influenced by mineral concentration of the culture medium and exposure to darkness for a period

Reduction of the mineral concentration of MS medium to half the normal value increased the rooting percentage of PR 204/84 explants when IBA concentration was 2.5 µM, and mean root number when IBA concentrations were 2.5 and 5 µM. Root elongation was stimulated at all IBA levels on both full and half strength media. By increasing IBA concentration from 0 to 10 µM, an increase in the mean root number per shoot was observed in both media (full and half strength). The mean length of roots was not significantly affected by IBA and mineral concentration of the culture media. In a second experiment, after 12 days of culture of shoots in a dark room followed by 12 days in standard growth room conditions, rooting percentage of shoots increased in comparison to shoots grown for 24 days in standard growth room conditions with IBA concentrations 1 and 2.5 µM.