The special conditions during in vitro culture result in the formation of plantlets of abnormal morphology, anatomy and physiology. After ex vitro transfer, these plantlets might easily be impaired by sudden changes in environmental conditions, and so need a period of acclimatization to correct the abnormalities. This review is focused upon contemporary information on the changes in leaf structure, water relations and photosynthesis during acclimatization of plantlets to ex vitro conditions. It also describes some ways of improving plant survival and for the speeding up of acclimatization.

Acclimatization of Micropropagated Plants to Ex Vitro Conditions

A substantial number of micropropagated plants do not survive transfer from in vitro conditions to greenhouse or field environment. The greenhouse and field have substantially lower relative humidity, higher light level and septic environment that are stressful to micropropagated plants compared to in vitro conditions. The benefit of any micropropagation system can, however, only be fully realized by the successful transfer of plantlets from tissue-culture vessels to the ambient conditions found ex vitro. Most species grown in vitro require an acclimatization process in order to ensure that sufficient number of plants survive and grow vigorously when transferred to soil. This article reviews current and developing methods for the acclimatization of micropropagated plantlets.

Acclimatization of tissue cultured plants

Herbaceous and woody plants propagated in vitro are frequently affected by the redundant presence of various culture factors that lead to metabolic and morphological derangements. Anatomical, morphological and physiological anomalies in tissue cultured plants have been described by diverse terminology — vitrification, translucency, hyperhydration, succulency and glassiness. Although vitrification is a misused term because it refers to a physical and not a biological process, it is the most often used one, since it describes changes in the leaves, giving rise to a glassy appearance.

Vitrification: morphological and physiological disorders of in vitro plants

Substantial numbers of micropropagated plants do not survive transfer from in vitro conditions to greenhouse or field environments. The greenhouse and field have substantially lower relative humidities, higher light levels, and septic environments that are stressful to micropropagated plants compared to in vitro conditions. Most species grown in vitro require an acclimatization process in order to insure that sufficient numbers of plants survive and grow vigorously when transferred to soil.

I. Simpkins

Papers

Abscisic Acid and the Regulation of Water Loss in Plantlets of Brassica oleracea L. var. botrytisRegenerated Through Apical Meristem Culture

Redistribution of Rubidium in Plants of Chrysanthemum morifolium Ram. cv. Snowdon Derived from Tissue Cultures and Transferred to Soil

Sodium Accumulation by Leaves of Cauliflower Plantlets and the Effect of the Mode of Plant Formation

Stomatal Responses of Phaseolus vulgaris L. Seedlings to Potassium Chloride in the Nutrient Solution

Response of Cultured Embryos of Phaseolus vulgaris and Hordeum vulgare to Farnesol