Effect of medium components on in vitro plant regeneration of African violets Saintpaulia Ionantha Wendl.,).

Abstract

African violets are routinely cuttings. In vi t.ro regeneration of propagated plants including by leaf has been demonstr-ated in several crop species African violets. Opt imal in vit.ro cu Iture conelitions for Afr ican violets shoot regeneration were investigated. Su.crose, glucose and fructose were found to be satis£actor-y sources of sugar in in vitro culture and plant regene:r;ation of African violets but lactose inhibited the establishment of explants and their morphogenesis. The best sugar was sucrose for the purple blue clone but fructose and glucose promoted the highest number of shoots in the wh i te clone. Adventitious shoot formation inC'>:'8r:t:w3heedn sucrose concentration was incr-eased from 1 to 3 % but further incr-ease to 5 and 7 % resulted in reduction of shoot regeneration. High concentr-ation of sucrose tended to promote r-oot formation and also had inhibitory effects on growth of the few r-egener-ated shoots. 1orphogenic responses prior to shoot formation such as tissue thickening, expansion of leaf exp lant e and nodule for-mation were qu i te sim ilar in the purple b 11.18 arid wh i.te clones of African violets. Regeneration of either or both shoots and roots were apparent within 22 days after explant cul ture _ The best results in terms of adventitious shoot formation were obtained with the use of full strength of ni trogen in MS medium for the purple blue clone and half strength of nitrogen for the white cLone . Lowering the concentrations of NO-3 and NH+4 ions resulted in the reduction of shoot and root formation for the purple blue c Lorie . Similar results were obtained for the white clone when concentration of ni trogen was reduced below half strength _ The • number of shoots. obtained per explant significantly decreased by decreasing the concentration of nitrogen in MS medium. African violets had an obligatory requirement for inorganic nitrogen (NO-3 and NH+4) because leaf tissues died on medil~ containing organic nitrogen source in form of urea. Shoot regeneration was higher for the white clone than the purple blue one at the different MS medium pH. Itwas evident the t rhizogenesis was generally higher in the whi te clone than in the purple blue one. The number of shoots obtained per explant were significantly affected by the pH of the medium. Culture medium with L.\)mg-~ NAA and 2 _Omg-1 BAP ,,"CiS found to be optimal for shoot regeneration of African violets. There was no shoot formation in a medium without cytokinin Cind an increase in auxin (NAA) concentration resulted in promotion of root formation. Shoot regeneration w~s found to occur on the surface of leaf expLants without an intermediate callus formation.