Effect of pH, Sucrose Concentrations and Medium States on in vitro Root-ing of Pineapple (Ananas comosus (L) Merr) cv Queen

The effect of medium states (liquid, semi solid, solid), pH (5.0, 5.5, 6.0, 6.5) and sucrose concentrations (10, 20, 30, 40 g/l) on in vitro rooting of pineapple cultured in full strength MS enriched with IBA at 0.5 mg/l were investigated. According to average overall sucrose concentrations, overall pH adjustments, and at each combination of equal sucrose and pH, liquid medium was always super than solid and semisolid. The tallest plantlets (66 to 71 mm) obtained in liquid medium enriched with sucrose at 10 and 20 g/l both adjusted to pH 6.0; sucrose at 20 g/l and adjusted to pH 6.5 and sucrose at 30 g/l and adjusted to pH 5.0. All of the above combinations except sucrose at 20 and pH 6.0  resulted in 100% rooting. Sucrose at 30 g/l and pH 5.0 resulted in two times more (11 roots per shoot) and three times longer roots (39 mm) than the other treatments (5 roots each about 14 mm long). Each rooting parameter had different optimum combinations of medium state, sucrose and pH adjustment. For any parameter, proper pH adjustment could reduce the optimal sucrose enrichment from 30 to 20 and even to 10 g/l. Hence, pH adjustment is suggested as an important approach for reduction of in vitro rooting medium cost.