Culture of Immature Embryos of Coconut, Cocos nucifera L: Callus Proliferation and Somatic Embryogenesis

The culture of immature embryos of coconut (Cocos nucifera L var. typica) was attemptedwith a view to developing a technique for clonal propagation. Embryos, 6-7 monthspostanthesis produced whitish, compact, embryogenic callus tissues in the presence of 12-20uM 2,4-D. Callus was maintained by subculture on a medium of the same composition.About 50% of the callus cultures produced globular embryos when transferred to 8 pM 2,4-D.Embryos in 22% of these cultures germinated and produced shoots, 6 mm long, when 6-benzylamino purine and kinetin (10 p.M each) were incorporated into the culture medium.The age of the embryo was an important factor determining callus proliferation andsubsequent embryogenesis. More than 50% of embryos excised from 6-7-month-old nutsproduced embryogenic callus tissues. Five to six-month-old nuts were not mature enough forexcising the embryos. Embryos from older nuts (8 months and above) germinated in culture.Only a small portion of the immature embryo produced embryogenic callus tissues. Thefuture root region proliferated into a brownish callus which in turn produced roots profusely.The cotyledon of the immature embryo expanded and developed into a haustorium withoutany sign of callus formation. The shoot apex produced a few plumular leaves but no callusingwas observed.