Vol. 85 No: 4

Title:
Effect of in vitro topophysis on the growth, development, and rooting of chrysanthemum explants (Chrysanthemum × grandiflorum /Ramat./ Kitam)

Authors:
M. ZALEWSKA, N. MILER and A. WENDA-PIESIK

pp: 362-366

Abstract:
The consequences of using ex vitro, single-node explants from different topophysical positions in chrysanthemum (Chrysanthemum × grandiflorum /Ramat./ Kitam) were determined. In particular, how explant topophysis affected the rate of propagation, which is important for the successful micropropagation of chrysanthemum. Uniform shoots of five cultivars of chrysanthemum, cultured in vitro, were each divided into three equal zones: distal, central, and proximal. Two single-node explants were isolated from each zone and cultured on MS medium without any added growth regulators. After 10 weeks of culture, 50% of the shoots that had developed from axillary buds on each single-node explant were excised and measurements were taken in order to compare those shoots that had developed from explants from the different topophysical zones. The remaining shoots were sub-cultured on rooting medium. After 4 weeks, the numbers of roots per plantlet, and the total fresh weight (FW) of roots were recorded. The cultivars fell into two groups. ‘Lady Amber’, ‘Lady Orange’, and ‘Lady Vitroflora’ explants were topophysis-dependent, while ‘Lady Bronze’ and ‘Lady Rosy’ explants were topophysis-independent. For the three topophysis-dependent cultivars, the propagation rate, growth rate, shoot length, internode length, single leaf weight, and total plantlet FW values were highest for those shoots derived from the central and proximal zones. Topophysis failed to affect the number of leaves per shoot or the number of days between the appearance of two successive leaves. The effects of topophysis on the number of roots per plantlet and on root FW were inconsistent. The unequal growth of chrysanthemum plantlets during in vitro micropropagation can be an effect of topophysis, and this phenomenon is cultivar-specific in chrysanthemum.

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