Studies On The Mutagenic Effects Of Pingyangmycin On Dendranthema × Grandiflora With Small Inflorescence In Vitro

The studies include three parts.The first one was effect of PYM on in vitro culture of D. × grandifolium with Small Inflorescence. Leaves and stem segments, which from in vitro cultural plantlets of two chrysanthemums with small inflorescence and as the explants, were treated by PYM with different concentration of 1, 2, 4, 8 mg/L. The result showed that PYM could dramatically inhibit calli induction and differetiation of explants. With the increasing of PYM concentration, both the calli induction rate and differentiation rate decreased, and reached the lowest when treated concentration was 8 mg/L. Calli induction rate and differentiation rate from stem segments culture and cultivar'Sliver Star' were higher than that from leaves culture and cultivar 'Italy Red'. The interactions between genotype and PYM concerntration, explant type and PYM concerntration, among genotype, explant type and PYM concerntration led to different effect on the calli induction and differentiation. Whereas, the F test indicated no significant difference in the interaction between genotype and explant type on both calli induction and differentiation.The second was performance of some traits in M₁ generation. An observation was made on some characters of M₁ plants regenerated from stem explants treated by PYM, a mutagenesis inducing chemical. The result showed that the average height, crown diameter, internode length and ratio of leaf length and width of the Ml plants decreased as compared to untreated ones. Whereas, flower diameter, number of tubular and ray florets all increased after PYM treatment. In addition, variations of flower color, flower type, leaf color and leaf type were also observed in M₁ generation. With the increasing of PYM concentration from 1 to 8mg/L, the ratio of variation in flower type, e.g. downwards extend or sharp tip of ray florets, was 0%, 2.5%,3.3%and 1.2%, respectively. The ratio of variation in flower color, i.e. turning pale, was 0% , 2.5%, 3.3%and 1.2%, respectively. It can be concluded that the optimal induction concentration of PYM is 4mg/L for mutagenesis of D.× morifolium 'Italy Red'.The last one was variation analysis of regenerants screened from traits via random...