Culture medium pH and growth of brazilian ginseng in vitro cultured plantlets

The present research aimed to evaluate the effect of culture medium pH on some growth parameter of Pfaffia glomerata (Spreng.) Pedersen in vitro cultured plantlets, as well as to check whether the explant's growth alters the culture medium pH. Four treatments consisted of different values (3.7; 5.0; 6.0 and 7.5) of culture medium pH were tested. The culture medium pH was adjusted prior to the addition of agar (6g L(-1) - Merck) and autoclaving. Nodal segments front asseptic plants grown in MS medium were used as explants. Front 9 to 15 days after inoculation (DAI) of nodal segments, the higher number of roots was obtained at pH 6.0, and the lower at pH 7.5. At 35 DAI, both length of the higher sprout and total number of nodal segments per plantlet were greater at about pH 6.0. At 35 DAI, roots biomass was lower at pH 3.7. On the other hand, shoots biomass was lower at pH 7.5. Fresh and dry matter of the whole plantlet was greater at pH around 6.0. In conclusion, values of culture medium pH near to 6.0, adjusted prior to autoclaving, are ideal for the growth of P. glomerata in vitro cultured plantlets. Moreover the in vitro growth of plantlet modified significantly the culture medium pH.