Effect of Nutrient Media and KNO3 on <i>in Vitro</i> Plant Regeneration in <i>Saraca asoca</i> (Roxb.) Willd

Abstract

Forest trees in general and those belonging to family Fabaceae in particular, have proved to be recalcitrant for propagation through tissue culture. Saraca asoca (Roxb.) Willd. (Family-Caesalpinaceae) is one such tree which has become vulnerable in nature due to over exploitation of its bark. Four nutrient media [MS (Murashige and Skoog Medium), WPM (Woody Plant Medium), B5 (Gamborg’s Medium) and NN (Nitsch and Nitsch Medium, 1969)] and five doses of BA (N 6 -Benzyladenine) (0, 2.2, 4.4, 8.8 and 17.8 μM) and their all possible interactions were tested for shoot induction and proliferation from nodal segments of 3-year-old plants. B 5 medium supplemented with 2.2 μM BA was screened out as the most suitable medium shoot induction, proliferation and elongation of regenerated shoots. In order to enhance shoot number, the nitrogen source in B5 medium was modified and five strengths of KNO 3 (0.25×, 0.5×, 1.0×, 1.25× and 1.5×) were tested. The different strengths of KNO 3 (Potassium nitrate) had statistically significant effect on number of shoots and on 0.25× strength of KNO3, maximum number of shoots (1.92) were obtained. The modified strengths of KNO 3 did not significantly affect the elongation of shoots. Effect of 5 durations (quick dip, transfer of shoots after 1 day, after 3 days, after 5 days and after 7 days) of pulse treatment with 200 μM IBA (Indole-3-butyric acid) in 1/2 strength MS liquid medium was tested. Thereafter, the shoots were transferred to semi-solid half strength MS medium supplemented with 0.2 μM IBA and 3.96 μM phloroglucinol. Pulse treatment of 5 days duration resulted in 37.5% in vitro rooting of shoots. Plantlets were hardened in soilrite soaked with half strength MS medium in culture room and later shifted to a soil mixture in shade house.