HIGH-EFFICIENCY PLANT-REGENERATION FROM COTYLEDONS OF WATERMELON (CITRULLUS-VULGARIS SCHRAD)

Cotyledons of various ages from seedlings of eight watermelon (Citrullus vulgaris) cultivars were cultured on MS medium supplemented with different combinations of phytohormones. High frequency shoot regeneration (60.0-92.0%) was induced from 5-day-old cotyledons of cultivars cultured on MS medium containing 5.0 mg/l 6-benzylaminopurine (BA) and 0.5 mg/1 indole-3-acetic acid (IAA). Multiple shoot buds elongated on MS medium containing 0.2 mg/l kinetin (KT) and 5-10 shoots per explant could be recovered depending on the cultivars. Elongated shoots rooted on MS medium with 0.1 mg/l alpha-naphthalene acetic acid (NAA). Zeatin riboside (ZT) had a similar efficiency as BA in shoot than 2-isopentenyladenine (2iP) or kinetin (KT). Cotyledons from 5-day-old seedlings were the most responsive to shoot induction.