Effects of low light intensity and high air humidity on morphology and permeability of plant cuticles, with special respect to plants cultured in vitro

Abstract

It has become something of an established fact that plants cultured in vitro from tissue explants have less cuticular waxes than normal plants. This appears plausible, for in the virtually water vapour-saturated atmosphere of the culture vessel they don’t ‘need’ a good water barrier on their surface, and thus wax synthesis is more or less superfluous. When plantlets are removed from the culture vessels after some weeks and exposed to the greenhouse atmosphere for further cultivation, rapid desiccation and eventually death occur frequently and cause great economic losses at this stage. It was found that with carnation plantlets the survival rate after removal from the culture vessels was 25 times higher if the plantlets had formed glaucous leaves in vitro, as compared to the majority of plantlets which had formed non-glaucous leaves [33]. From findings such as this, the general conclusion has been made that high cuticular water loss contributes substantially to the desiccation problem, in addition to transpiration through non-functional stomata and water uptake problems due to underdeveloped or absent roots.