Shoot number and shoot size as affected by growth regulators in in vitro cultures of Spathiphyllum floribundum L.

The average number and average fresh weight of Spathiphyllum floribundum cv . Petite axillary shoots grown on MS medium with three concentrations of BA (1, 2 and 5 mg l(-1)) in the absence of auxin or in combination with 0.05 mg l(-1) NAA, 0.5 and 1.0 mg l(-1) IAA or 0.005, 0.05 and 0.1 mg l(-1) 2,4- D were determined. In general, higher shoot number and fresh weight values were achieved in all tested levels of BA combined with 0.05 mg l(-1) NAA th an in combination with IAA or 2,4-D. The best response in terms of average shoot number (5.8), average fresh weight (116 mg/explant), leaf number/plan t (14.7), lateral shoot number/plant (5.3), plant diameter 14.2 cm), and pl ant height (13.0 cm) was observed in shoots cultured on medium containing 0 .05 mg l(-1) NAA+ 2 mg l(-1) BA. The shoots produced in this treatment grew vigorously when the plants were acclimatized under greenhouse conditions. When shoots were grown on MS medium with the above combinations and added o f 1 mg l(-1) Kin, the highest shoot number (11.6 shoots per explant) was ob served in the presence of 1 mg 1(-1) IAA + 2 mg l(-1) BA + 1 mg l(-1) Kin i n which an average fresh weight of 39 mg/shoot was achieved. The importance of using a particular shoot size (minimum fresh weight) for better adaptat ion of plants to soil is discussed. Micropropagated plants of 20 mm height and more than 66 mg weight grew best following acclimatization in the green house. (C) 2001 Elsevier Science B.V. All rights reserved.