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Abstract Sandalwood (Santalum album L.) is a small evergreen, hemi-parasitic tree having more than 18 woody species that are mostly distributed in South Asia, Australia, and Hawaii. Its economical importance is derived from its heartwood oil, but its difficult propagation makes conservation essential. The percentage of seed germination is poor and germination time exceeds 12 mo. Vegetative propagation can be accomplished by grafting, air layering, or with root suckers, but the production of clones is inefficient and time consuming. In this study, efficient plant regeneration was achieved via indirect organogenesis from callus cultures derived from leaf tissues of S. album. Callus induction was induced when leaf explants were cultured on woody plant media (WPM) supplemented with either thidiazuron (TDZ) or 2,4-dichlorophenoxyacetic acid. The highest callus frequency (100%) was obtained when leaf tissue was cultured in themediumwith 0.4 mgl-1 TDZ. Freshweight (141.92 mg) and dry weight (47 mg) of leaf-derived callus were highest in the medium supplemented with 0.8 mgl-1 TDZ. The WPM medium supplemented with 2.5 mgl-1 BA+0.4 mgl-1 NAA was the most effective, producing the highest number of shoot buds (24.6) per callus. The highest number of shoots per explant (20.67) and shoot length (5.17 cm) were observed in media supplemented with 5.0 mgl-1 BA and 3.0 mg1-1 Kn, respectively. Plantlets were rooted on WPM medium with different concentrations of indole-3-butyric acid (IBA). The highest rooting percentage (91.67) and survival were achieved usingWPMmedia with 1.5 mgl-1 IBA. All plantlets survived acclimatization, producing healthy plants in the greenhouse. The current investigation showed efficient in vitro regeneration capabilities of S. album from leaf explants.
Keywords Callus induction . Callus frequency . Shoot bud . Sandalwood . Acclimatization
Introduction
Sandalwood (Santalum album) is a hemi-parasitic tree, occurring in semiarid areas from India to the South Pacific and the northern coast of Australia. In India, it is mostly found in the states of Andhra Pradesh, Karnataka, Tamil Nadu, Gujarat, Madhya Pradesh, and Maharashtra. Sandalwood from the Mysore region of Karnataka in Southern India is widely considered to be of the highest quality. It grows in geographical locations that receive 850-1,350 mm annual rainfall, with temperatures ranging from 25°C to 35°C (Rao et al. 2007). The tree is medium sized, about 12-15 m tall, and reaches its...