Studies On Inheritance And Hybridization Breeding Of Male Sterile Two-Type Lines In Zinnia Elegans

As an important ornamental plant throughout summer and autumn months, common zinnia(Zinnia elegans Jacq.) is an extremely popular annual plant that includes a wide variety of flower types and flower colors, and has a long-lasting bloom. Although hybridization using male sterile lines is common practice in commercial applications of Zinnia elegans overseas, there has been no systematical report on the inheritance and hybrid breeding of male sterile two-type lines in the species. Consequently, future breeding efforts will largely focus on male sterile lines. In this study, the inheritance, morphology and cytology of male sterile two-type lines J16AB was investigated, and NCII incomplete diallel crossing was carried out with five male sterile lines of the male sterile two-type lines as female, and fourteen inbred lines as male, the combining ability, heritability and principal component of twelve ornamental characters were analyzed. The results were presented as following:(1) The inheritance of J16AB The segregation ratio of progenies by sibmating, selfing and test cross confirmed that the male sterile two-type line J16AB was controlled by a pair of recessive nuclear gene, the male fertile plants were dominant heterozygote, whose genotype were Msms; the male sterile plants were recessive homozygote, with the genotype of msms. There were no dominant morphological differences between male fertile plants and male sterile plants until the color bud stage; in the color bud stage, we can see curling petals of ray florets at the top of floral organs in male fertile plants, but there were only exposed filaments at the top of floral organs in male sterile plants; in the flower stage, the male fertile plants showed stretching ray florets, big and full anthers of disc florets, and pollens which were keeping normal fertility, but in the male sterile plants, the petals of ray florets were degenerated, the stamens were also degenerated and became filamentous and villous without pollen inside, and the pistils developed normally. In the male fertile plants, development of the mature pollen grains was followed through the initiation of the archesporial cell, sporogenous cell, microsporocyte formation, tetrad stage and uninucleate developmental period; in the male sterile plants, the anther was not have the differentiation to produce the microsporocyte formation and pollen; in a word, J16AB is male sterility of structural type.(2) Analysis of combining ability, heritability and principal component of NCII incomplete diallel crossing The analysis of combining ability, principal components and heritability of twelve horticultural characters indicated that the additive effects of Plant height, Crown size and Length of node were bigger than the non-additive effects, and both the broad sense heritability and narrow sense heritability were high, so they could be effectively selected in the early generations; Pedicel length showed approximately equivalent maternal and paternal additive effects, high broad sense heritability and medium narrow sense heritability, it also could be effectively selected in the early generations; the other eight traits displayed bigger non-additive effects, got more environmental influencement, could be hybridization by heterosis; there was no causal relationship between general combining ability and specific combining ability effects; in the hybrid breeding of male sterile two-type line of common zinnia, the improvement and selection of male sterile two-type lines should be a particular focus of attention; it is feasible that we can forecast the Diameter of center disk and Pedicel length by the determination of Plant height, Crown size, Number of branches, Leaf length and Leaf width, when using the phenotype characters on the classification of F1 generations of common zinnia, we should consider the plant’s vegetative growth conditions and pedicel length first, followed by petals of flower organ size and strength as the standard.(3) Investigation of parents and hybrid combinations of NCII incomplete diallel crossing S5001AB, AH002AB and inbred lines A1-GH, A3, J14 were chosen as ideal parents for potted flowering plants; AH209AB, J16AB and inbred lines S5, J10, J17 were chosen as ideal parents for cut flowers; the crosses AH002A×J17, AH209A×A1-GH, S5001A×J6 and AH002A×S5, AH003A×A3, J16A×J6 were chosen as primary and secondary promising combination for producing potted plant characteristics, respectively; AH209A×S5, AH209A×J17, J16A×J17 and AH209A×J9, S5001A×J10 were the primary and secondary hybrid obtained in this study for cut flower traits; we should ordering AH002A×A3, AH003A×J6 and J16A×J9 priority when we want to attain big and double flower hybrids.