| The peony and the tree peony are flowers like sisters. In the north central plains, the natural flowering stage of the tree peony is in the middle of April, while the natural flowering stage of the peony is in the early May. If we could cultivate the varieties of this flowering stage, they will plent the peony and tree peony garden. As Cross breeding is one of the main means to breeding new varieties, the study used Paeonia veitchii,’Fen Yu Nu’,’Zi Feng Yu’ and’Fen Xia Man Tian’ to design cross combinations, which is’Fen Yu Nu’×Paeonia veitchii,’Fen Yu Nu’×’Fen Xia Man Tian’,’Zi Feng Yu’×’Fen Yu Nu’. Then we determined the pollen viability of male parents, counted the fruiting rate of female parents, observed the cytological and morphological process of cross combinations, and obtained the below results:(1) The pollen viability showed:the wild peony rank in this order as follows:Paeonia veitchii (Gansu), Paeonia veitchii (Sichuan), P. anomala; the pollen viability of the wild peony decreased sharply after a year of storage. The highest pollen viability of peony varieties was62.8%of’Fen Xia Man Tian’, the middle pollen viability of peony varieties was17.5%of ’Yan Zi Xiang Yang’, the lowest pollen viability of peony varieties was17.5%of’Fen Yu Nu’. The pollen viability of peony varieties was higher than the wild peony’s.(2) The observations of fertilization process by fluorescence microscopy showed:the three fertilization processes differed in cross combinations.’Fen Yu Nu’×Paeonia veitchii:a large number of callose was discovered in the stigma surface and pollen tube. The generated number of pollen gains after12hours by pollination was lower, most pollen tubes circles in the stigma surface during12-24hour, and some pollen tubes could reached the middle of style, no pollen tube was observed to achieve fertilization after12hours by pollination.’Fen Yu Nu’ x’Fen Xia Man Tian’:callose reaction was discovered in pollen tube and ovule inside. Most pollen gains could adhere to the stigma surface and generated after1-4hours by pollination, most pollen tubes could reached the middle of style, while some pollen tubes could pass through the whole style, enter into the ovule to achieve fertilization.’Zi Feng Yu’x’Fen Yu Nu’:no callose was discovered during fertilization process. Most pollen gains could adhere to the stigma surface and generated after1-2hours by pollination, most pollen tubes could pass through the whole style after24hours by pollination, pollen tubes entered into the ovule along the ovule wall after48-72hours by pollination, and entered into the embryo sac via micropyle to fertilization.(3) The observations of embryonic development process showed:’Zi Feng Yu’x’Fen Yu Nu’:could went on normal embryonic development process, the zygote after dormancy divided into two cell pre-embryo in9-12day by pollination, two cell proembryo divided continually with suspensor extended after15-20days by pollination, embryo proper divided continually with globular embryo proper formed after30days by pollination, globular embryo proper divided continually with heart-shape embryo formed after40-50days by pollination, the torpedo-shape embryo proper was formed preliminarily after60days by pollination, he torpedo-shape embryo proper divided continually until the seed matured.’Fen Yu Nu’×’Fen Xia Man Tian’:the embryonic development process was un-continued and abnormal, the zygote was discovered disassembly, and the embryo sac was full of endosperm without embryo when seeds matured.(4) The morphological observations of carpel and ovule showed:’Fen Yu Nu’×Paeonia veitchii:the carpel of female parent grew slowly, while the ovule were negative growth during15days by pollination; the carpel wilted gradually, while the ovule nearly stop development after15days by pollination.’Fen Yu Nu’×’Fen Xia Man Tian’:the carpel grew sharply while the ovule grew slowly during40days by pollination, then the carpel and most ovules grew slowly with wilted and shrunk.’Zi Feng Yu’x’Fen Yu Nu’:both the carpel and the ovule could grow normally with time increased after pallination, so were the nature’Zi Feng Yu’and’Fen Yu Nu’.(5) The counting results of the fruiting rate showed:the fruiting rate of cross combinations was low.’Zi Feng Yu’×’Fen Yu Nu’:the cross combination obtained some intact seeds, with22.6%fruiting rate, which raised5%compared with female parent’s nature fruiting rate. When’Fen yu nu’was female parent, the fruiting rates of cross combinations were lower than’Fen yu nu’nature fruiting rate.’Fen Yu Nu’x’Fen Xia Man Tian’:the cross combination obtained some seeds without embryo, and the fruiting rate was9.1%,’Fen Yu Nu’x Paeonia veitchii:the fruiting rate of this cross combination was0%without seeds. The suitable female parents were’Zi Lian’,’Fen Yu Nu’,’Zi Feng Yu’ according to the fruiting rate of peony varieties in2011. Compared the fruiting rate of’Fen Yu Nu’with’Zi Feng Yu’ in two years, we discovered the fruiting rate of’Fen Yu Nu’ was above50%, while the fruiting rate of’Zi Feng Yu’was below50%. Except the formed seeds per flower, other three fruiting rates (the formed seeds per carpel, the formed seeds per ovule, the fruiting carpel rate) could show the same fruiting rate order of different peony varieties or cross combinations consistently.(6) As a early-flower peony variety, we studied’Fen Yu Nu’specially. The pollen viability was17.5%, the fruiting rate of self-pollination was0, while the fruiting rate of nature pollination was above50%. When’Fen Yu Nu’ was female parent, the fruiting rates of cross combinations were lower than’Fen Yu Nu’ nature fruiting rate, and the cross seeds was lack of embryo. When’Fen Yu Nu’ was male parent, the fruiting rates of cross combination was higher than’Fen Yu Nu’ nature fruiting rate, and the cross seeds was intact. |
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