| Self-cross, hybridization, interspecific cross and embryo rescue were performed in or between diploids D. nankingense, D. lanandulifilium, D. dichrum, tetraploid D.indicum, autotetraploid D. nankingense(4x), hexaploid D. chanetii, hexaploid D. vestitum and D. morifolium(hexaploid and its aneuploid). The results were as follows:1. Chrysanthemum posesses self-incompatibility. It was easier to obtain hybrid between the same ploidy species or between tetraploid and hexaploid species, but incongruity occurred when crosses were conducted between diploid and tetraploid or hexaploid species and it was difficult to obtain interspecific hybrid. All treatments did not effectively overcome self-incompatibility and incongruity of interspecific cross.2. The genotypes and the days of embryo were the important affect factors of rescue. 13~18 days embryo were the suitable time for rescue. Medium type had little effect on ovary culture, beneficial proportion of hormones was BA2.0 mgL-1+NAA2.0 mgL-1 and KT2.0 mgL-1+IAA2.0 mgL-1. Incubation at 21 C or 26 C was better than at 16 C, and light had no significant on culture at 21 C. The rescue result was better when diploid species used as female parents than as male parents.3. Identification of interspecific hybrid in Dendranthema by RAPD and morphology were studied . The result of RAPD analysis showed that the hybrid presented specific bands of male parent or new bands. The hybrids characteristics were generally between that of the parents and mostly resembled the higher polyploid parent. Some hybrids were characterized by specific traits of the male parent or new traits. The morphological traits of hybrids between diploids and chrysanthemum cultivars varied in a large range, which indicated that the polyploid cultivated chrysanthemum possessed complexed genetic background.4. The infecundity of self-cross and interspecific cross in Dendranthema was studied by observations of seed sets and sexual process between two varieties and two wild species . The results showed that self-incompatibility of chrysanthemum presented by low pollen adhesion and low pollen germination on the stigma, the pollen tubes abnormal growth and hand to penetrate into the stigma. The incongruity of interspecific cross showed thesame abnormal phenomenon, but it was better than that of self-cross, a few pollen tubes can penetrate into the stigma.5. The relationship of 23 wild species, cultivars and interspecific hybrids in Dendranthema was studied by RAPD analysis. The results from pairwise similarity and UPGMA cluster analysis, combining with the fecundity of hybridization and rate of plantlet of embryo rescue, suggested that when parents have closer relationship, the genetic distance was closer, the compatibility of hybridization was better, fecundity was higher and embryo rescue was easier. When parents have further relationship, the results were contrary.6. By the study of characteristics, pollen fertility and self-cross fecundity of Fj hybrids, we found that some interspecific hybrids could not flower normally, pollen was infertile and the self-cross fecundity was low. Chromosome doubling, colchicine treatment and backcross can apparently improved fecundity. Embryo rescue after backcross not only can solve the problem of low fecundity, but also can improve the rate of platelet.7. An observation was made on several flower characters of FI generation in Dendranthema, which obtained from interspecific cross or embryo rescue among wild diploid species D. lavandulifilium, D. nankingense, D. dichrum, tetraploid D .indicum, tetraploid D. nankingense(4x) and D.monfolium(hexaploid and its aueuploid). The results showed that polyploid chrysanthemum varieties had stronger flower color genetic ability than diploid and tetraploid, the purple and white color of flowers were stronger than yellow. The inflorescence diameter , number of ray florets and tubular florets appeared heterosis in F1 generation. The hybrid's mean inflorescence diameter, the number of ray florets and tubular florets were 112.4%,...
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