Abstract. We investigated changes in physiological characteristics of micropropagated juvenile avocado (Persea americana Mill.) cultured in three different sucrose concentrations (5, 30 and 50 g/l) for 4 weeks and subsequently acclimatized to ex vitro conditions. No significant differences in foliar concentrations of total chlorophylls, Nmass, flavonoids and total soluble proteins were observed during in vitro growth or after acclimatization. However, ex vitro transfer exerted multiple effects on foliar ratios of chlorophyll a to b, total chlorophylls to carotenoids and stem N and C/N ratio. Both varying sucrose concentrations during in vitro growth and ex vitro transfer, affected the concentration of rubisco subunits independent of other photosynthetic components, viz. total chlorophylls, foliar N and total soluble proteins. These results suggest that preconditioning juvenile avocado microplants at different concentrations of sucrose modify several physiological parameters during ex vitro acclimatization, like concentrations of carotenoids and rubisco, which can improve vigour of plants in autotrophic conditions.
