UTILIZING HYDROPONICS TECHNIQUE FOR ACCLIMATIZING TISSUE CULTURE DERIVED PLANTLETS UNDER DESERT ENVIRONMENT

Abstract

Most plants derived from in vitro conditions require an acclimatization process to ensure the survival of sufficient number and vigorous growth of plantlets when transferred to soil under ambient conditions. Protocols for micro propagation of many plants have been standardized but their acclimatization under harsh desert conditions continues to be a difficult task in the micropropagation industry. During in vitro culture plantlets grow under higher humidity, lower irradiance, lower water potential, higher risk of contamination and microbial activities. Addition of growth regulators to the medium may cause abnormal morphology, anatomy and physiology. When these plantlets are exposed to higher irradiance and lower humidity the plantlets may quickly wilt as water loss through transpiration is higher than that of absorption through roots. This condition is very severe in the desert regions where relative humidity is very low; irradiance and temperature are very high. For controlling water loss acclimatizing tubs are generally covered with plastic sheets, the resulting higher humidity invites fungal infestations. Heavy losses have been observed during the acclimatization process of in vitro derived plantlets in the desert regions. To overcome the above mentioned difficulties hydroponics techniques have been experimented for the acclimatization of three types of in vitro cultured plants: herb (strawberry - Fragaria × ananassa Duch.), shrub (rose - Rosa indica L.) and tree (date palm - Phoenix dactylifera L.). Results indicated that the survival rate and growth vigour was significantly higher in the hydroponically grown plantlets compared to their conventionally grown controls. Response to the two nutrient media used was also encouraging in the hydroponically grown plantlets. Transferring plantlets from the tube to a hydroponics system for a period of seven days has shown expedited establishment under ambient conditions in final soil media.