In vitro studies on S. allagophylla were carried out using, as a starting material, seeds collected from wild plants growing in "campo cerrado" vegetation at the Reserva Biológica e Estação Experimental de Moji-Guaçu, SP, Brazil. Two aspects of plant adaptation to cerrado conditions were tested in vitro: effect of pH and nutrient concentration, using the two traditional Murashige & Skoog (MS) e o de Gamborg et al. (B5) media. MS basic medium was modified in relation to pH by a gradient of initial pH values ranging from 4.2 to 5.8 at 0.2 pH unit intervals and with progressively lower concentrations of KNO3, KH2PO4 and MgSO4.7H2O. B5 medium was tested with standard or half-strength nutrients. Results shown that, in vitro, this material showed: increased growth in acid media and all explants cultivated in vitro regardless of the initial pH acidified the media; growth was not affected by the reduction of nitrate concentration and even B5 half-strength nutrients promoted growth, mainly in relation to leaf expansion; growth was the same in the complete presence or absence (in relation to the MS medium) of KH2PO4 and MgSO4.7H2O. These in vitro results are consistent with a plant well-adapted to absorbing nutrients in acid, nutrient-poor, aluminium-rich cerrado soils.
In vitro culture; acid pH; cerrado; Gesneriaceae