CALCIUM-MEDIATED CALLUS INDUCTION IN IMPATIENS-FLANAGANIAE

Previous studies have reported very low survival rate in vitro of youn g leaf explants of Impatiens flanaganiae (a rare plant of medicinal an d horticultural importance) as they suffered early senescence and subs equent death. B5 medium supplemented with 2.6 mg l(-1) 2,4-D and 1.25 mg l(-1) BA medium, (recommended for callus induction from leaf explan ts of I. flanaganiae) was modified by the addition of 0.0 mmol l(-1) 1 .02 mmol l(-1) or 5.1 mmol l(-1) Ca (treatment 1, 2 & 3 respectively) to study the effect of Ca on improving callus induction in this specie s. Treatment 3 induced callus formation in 3 weeks time, prevented ear ly senescence and enhanced the survival rate of explants to more than 80%. Peroxidase (POD) activity in explants cultured on all media was g reater than in intact leaves. Weekly analysis of POD activity in expla nts cultured on medium 3 Showed an initial low level of peroxidase, wh ich turned highest by the 5(th) week in comparison to the explants on other media.