The preparation of micropropagated plantlets for transfer to soil without acclimatization

Plantlets cultured in vitro on agar-based media in a water-saturated atmosphere wilt rapidly when transferred to normal greenhouse or field conditions. Water is rapidly lost from the leaves because stomata fail to respond to those stimuli that normally induce closure (1-4), and poor development of epicuticular wax results in loss of water through the cuticle (5-7). Uptake of water by the roots is limited by damage incurred during transplantation and by poor contact with the substrate. Problems of transplantation are accentuated in vitrified plantlets, which grow slowly and wilt rapidly. Reduced deposition of cellulose and lignin in these plantlets causes reduced cell wall pressure, leading to increased water uptake by the cells and a glassy turgescence of leaves and stems (8,9).