Indian Journal of Plant Physiology

The present study was focussed on micropropagation of Centella asiatica, its stomatal characteristics and percent water loss of in vitro grown leaves at culture establishment (CE), shoot multiplication (SM) and rooting (RT) stages in relation to acclimatization (AC) and field (FD) grown plants. Microscopic observations on the abaxial and adaxial leaf surfaces of AC and FD-grown plants showed elliptical stomata (length of 11–13 μm) with narrow apertures (2–4 μm pore width). In comparison, the stomata of leaves for in vitro cultured shoots and plantlets showed circular stomata (diameter of 13–15 μm) with widely opened apertures (6–7 μm pore width). Stomata on the either of leaf surfaces were not found to vary with respect to morphology especially shape and sizes. Abaxial leaf surface imprints have lowest stomatal index (SI) values when compared to adaxial leaf surface imprints. Leaves of CE, SM and RT had higher SI as compared to leaves of AC and FD. The percent moisture loss of in vitro leaves of CE, SM and RT was considerably greater than that of leaves of AC and FD. This holds true at each of 30, 60, 90 and 120 min interval of air-drying. The present study followed a simple acclimatization method to transfer rooted shoots from culture vessels to growth chamber under high humidity. Despite having stomata on both sides of the leaf, about 90% of the in vitro grown C. asiatica plantlets recovered from transpiration stress after 4-weeks of acclimatization. Reproducible micropropagation protocols with higher rates of survival are beneficial for the cost-effective production of medicinally important herbs like C. asiatica through saving resources in terms of time, labor and money.