Multiple shoot induction and plant regeneration in litchi (Litchi chinensis Sonn)

Multiple shoot induction in Litchi chinensis Sonn. (litchi) has been achiev ed by two methods: (1) direct germination of litchi seeds in 6-benzylaminop urine (20 mg l(-1))-supplemented MS liquid medium and supported on a filter -paper bridge and (2) in planta treatment with 6-benzylaminopurine (100 mu g on alternate days) of the axillary bud regions of plants germinated and m aintained under sterile conditions. While the former :method resulted in as many as 27.5+/-8.6 shoot buds from the cotyledonary node within 4 weeks, t he latter yielded on average approximately 8 shoot buds from each treated n ode in 8 weeks. The cytokinin treatment in planta consisted of placing ster ile filter paper moistened with sterile distilled water over the node and a dding different concentrations of 6-benzylaminopurine. Both methods of mult iple shoot induction were found to be effective for the five genotypes of l itchi that were tested. The shoots elongated and rooted directly in vermicu lite after a pulse treatment with IBA (25 mg/ml) for 15 min. Fungus growth which is a serious problem in litchi tissue culture, was controlled using a fungicide, Bavistin, and by eliminating organic nutrients from the growth medium.