Occurrence of in vitro flowering in coconut (Cocos nucifera L.)

Immature inflorescence with outer spathe length of 5.5 cm size collected from West Coast Tall cultivar of coconut was used as the explant and rachillae bits were inoculated in Y3 media supplemented with 2, 4-D (1 mg L-1). The cultures were incubated in dark for eight months and sub-cultured into the same media at monthly interval. The white shoot like outgrowths formed were sub cultured to 1/2 MS media fortified with 1 mg L-1 each of NAA and BAP and subsequently transferred to light condition. After three months, the emerging shoot like structure was transferred to Y3 media fortified with NAA and BAP. Upon developing 3 - 4 leaves, the cultures were transferred to rooting media and root initiation was observed after two months. The transition of vegetative shoot to reproductive state was accompanied by some morphological changes including rapid emergence of long and thin leaves followed by emergence of pearly white inflorescence. Unlike normal inflorescence, the inflorescence emerged was terminal and was devoid of spathe. Prolonged subculture in the same media might have resulted in pH variation and subsequent reduction in organic and inorganic constituents of the media. The chemical stress experienced by the plantlet might have induced in vitro flowering.