Studies on In Vitro Somatic Embryogenesis of Cocos nucifera L. (COCONUT)

Abstract

In vitro somatic embryogenesis is the most important means of mass propagating high quality-planting materials in Cocos nucifera L. (coconut). Despite long-term research, undertaken to develop suitable culture conditions for in vitro somatic embryogenesis and plant regeneration from a local variety (Sri Lanka Tall) of coconut. It also included studies on markers for early detection of tissues with embryogenic potential, comparative histological and biochemical studies on zygotic and in vitro somatic embryos at different developmental stages. During the study, embryogenic callus was initiated from plumule explants excised from pre-cultured mature zygotic embryos. The basal culture media, 72, Y3 and MS were found to be suitable for callogenesis when supplemented with appropriate concentration of 2,4-D (24 pM). However, the adsorption capacity of activated charcoal present in the medium determines the level of freely available 2,4-D in the medium and therefore it plays a crucial role in callogenesis. Under the most suitable combination of charcoal and 2,4-D (0.25 % Pharmacos charcoal with 24 pM 2,4-D and 0.1 % BDH, acid-washed charcoal with 100 pM 2,4-D), about 50 % plumule explants produced embryogenic callus. The callusing frequency in charcoal-free media was found to be lower (about 29 %) than that of charcoal-containing media. Attempts were made to produce friable callus for the establishment of cell suspensions. However, it was not possible to obtain friable callus during the course of the study and thus fine suspension cultures could not be established.