Response of immature inflorescence for in vitro regeneration on coconut (cocos nucifera L)

Abstract

Investigations on 'Response of immature inflorescence for in vitro regeneration in coconut (Cocos nucifera L.)' were carried out at the Centre for Plant Biotechnology and Molecular Biology, College of Horticulture, Vellanikkara during 2005 to 2006. Y3 medium was found to be the best basal medium for in vitro culture of immature inflorescence of coconut. Inflorescence of length 40 to 50 cm was found to posses male flowers at pollen mother cell stage of microsporogenesis. Wiping the spathe with 70 per cent ethyl alcohol before excising the immature inflorescence parts could effectively control contamination with 100 per cent culture establishment. The young inflorescence parts could survive up to 12 minutes treatment with 0.1 per cent HgCl2. Among the different explants tried, anthers at premeiotic stage and immature rachillae were found to be the best for callus induction and embryo formation. When the explants were inoculated the exudation of polyphenols from the explants adversely affected their survival. Polyphenol exudation was checked by incorporating PVP 0.1 per cent and activated charcoal 0.2 per cent in the medium and by incubation under dark condition. 2,4-D at 15 to 30 mgl-1 was found to be the most effective auxin for callus induction and proliferation. Y3 basal medium with growth regulator combinations of 15 mg l-1 2,4-D, 0.5 mg l-1 picloram, 1mg l-1 NAA and 0.1 mg l-1 TDZ was identified as the best medium for callus induction and embryogenesis of immature anther. Sucrose at 5 per cent concentration was identified as the optimum concentration for callus induction. Pretreatment of inflorescence at 4°C for 24 hrs or 30 hrs doubled the callus induction and reduced the browning of explant. Callus induction was observed from rachillae tissue in Y3 medium containing15 mg l-1 2,4-D, 1 mg l-1 picloram, 1 mg l-1 IAA and 0.1 mg l-1 TDZ.