| Dudleya belongs to Crassulaceae,also known as Sedum.It consists of three sub-genuses,with a total of about 100 species and sub-species.There are a large number of rare and endangered species in this genus.In recent years,many resources of this genus have entered China.It is not easy to leaf cutting and mainly depends on seed reproduction,but little is known about its reproductive biology.After being introduced into China,we often encounter some problems,such as no flowering period,low self-pollination rate and so on.Therefore,in this study,the external characteristics of seeds,germination characteristics,comprehensive characteristics of flowers,stigma receptivity,pollen vitality,ovule ratio and other breeding characteristics of several species of Dudleya were studied;at the same time,leaves were used as explants to screen the suitable hormone ratio of primary bud induction medium,so as to further provide reference for the breeding of Dudleya plants.It can provide the basis for the development and utilization.The main results are as follows:(1)The seed color of the six species of Dudleya are dark brown in color,spindle-like in shape,rough in surface,and have vertical thin ribs.The seed individuals were very small,belonging to small seeds.The individual seeds are very small and belong to small seeds.Among them,Dudleya palmeri seeds are the largest with 1.47 mm,0.57mm,0.57 mm,and 79.86 mg in length,width,thickness and thousand-grain weight,respectively.Dudleya brittonii seeds are the smallest,with a length,width,thickness and thousand-grain weight of 0.90 mm,0.32 mm,0.34 mm and 17.26 mg respectively.(2)The seed germination experiments of different temperature treatments showed that the optimal germination temperature and germination days of different species are different;the optimum germination temperature of Dudleya anthonyi,Dudleya semiteres and Dudleya brittonii was 15?,and the days of germination potential were the fifth day,the tenth day and the sixth day,belong to low-temperature seeds.Dudleya albiflora,Dudleya palmeri and Dudleya orcuttii could germinate in the temperature range of 15?30?,and they were all widely suitable seeds;the optimum germination temperature of the first two was 25?,the optimum germination temperature of Dudleya orcuttii was 20?,and the germination days were the second day,the third day and the third day respectively.(3)The research of flower characteristics showed that all the eight plants were bisexual flowers with cymes;Sepal base connate,apex divided into 5-lobed,all 5-lobed;There are 10 stamens,which are divided into inner and outer rings,and the outer anthers are powdered before the inner anthers;5 pistils,ovary superior.Some flowers have 4pistils,8 anthers and 4 sepals.The corolla of Dudleya anthonyi,Dudleya albiflora,Dudleya semiteres,Dudleya traskiae and Dudleya caespitosa is bell shaped,with 5pistil stigmas gathered together;The corollas of Dudleya edul,Dudleya densiflora and Dudleya viscida are star shaped,and the pistils gradually separate from the style upward.The flowers of Dudleya traskiae and Dudleya caespitosa are yellow,and the other six species are white;the calyx of Dudleya traskiae is yellow green,and the calyx of the other seven species are green.(4)Studies on pollen viability,stigma receptivity,pollen ovu Le ratio and hybridization index at different flowering stages showed that all the eight tested plants had pre mature stamens;there was no overlap between pollen viability period and stigma receptivity period of Dudleya edulis and Dudleya densiflora,suggesting cross pollination;the pollen viability period of the other six species overlapped with stigma receptivity period,but the pollen activity was weak in overlapping time.According to Cruden's P/O standard,Dudleya anthonyi,Dudleya albiflora and Dudleya densiflora belonged to facultative outcrossing,and the rest belonged to obligate outcrossing;according to Dafni's OCI evaluation standard,they were all mixed mating systems which were mainly outcrossing,partially self-compatible,and sometimes needed pollinators to participate.(5)The leaves of 5 species of Dudleya were used as explants,and MS+6 g·L-1agar+3%sucrose was used as the basic medium for primary culture.The results showed that the leaf explants of five species of Dudleya were mainly induced by bud,and the difference among species was large,and the callus induction rate was low.The appropriate ratio of hormone concentration for the leaf explants of Dudleya albiflora,Dudleya densiflora and Dudleya virens was 6-BA 4mg·L-1+NAA0.4 mg·L-1;the hormone concentration ratio of Dudleya semiteres primary culture medium was 6-BA3 mg·L-1+NAA 0.4 mg·L-1;Dudleya viscida was 6-BA 3 mg·L-1+NAA 0.2?0.3 mg·L-1. |
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