Acclimatization Strategies for Tissue Cultured Fruit Crops: A Review

Abstract

Effective acclimatization determines whether tissue-cultured fruit crop plantlets can survive the transition from controlled culture conditions to nursery and field environments. Plantlets developed in vitro commonly possess thin cuticles, poorly regulated stomata, weak stems, limited photosynthetic competence and underdeveloped root systems, making them vulnerable to water loss, transplant shock and microbial exposure. This review synthesises the principal in vitro and ex vitro strategies used to improve plantlet survival and establishment. Pre-transfer approaches include gradual sucrose reduction, improved vessel ventilation, light acclimation, carbon dioxide enrichment, photoautotrophic or photomixotrophic culture, growth retardants, storage-organ formation and mechanical conditioning. These practices can improve photosynthetic capacity, structural strength and stress tolerance before transplantation. Post-transfer management involves the selection of suitable potting substrates, regulation of humidity and light, judicious fungicide use, balanced nutrition, growth promoters, antitranspirants, ex vitro rooting, biohardening and hydroponic cultivation. Collectively, these interventions support root development, water balance, nutrient acquisition and adaptation to non-sterile conditions. The reviewed evidence indicates that acclimatization responses vary among crops and genotypes and are strongly influenced by culture conditions, substrate properties and environmental management. Therefore, commercially useful protocols should integrate compatible physiological, environmental and microbial interventions rather than rely on a single treatment. Crop-specific, cost-effective and sustainable hardening systems are essential for improving the reliability and scalability of tissue-culture-based fruit crop propagation.