| This paper explored the germplasm resources' preservation in vitro of loquat (Eriobotrya japonica Lindl.)- The study included the establishing of propagation system and the factors that affected the quality of the preservation in vitro of loquat's germplasm. The cryopreservation study of loquat was also been explored. The main results were as follows:1. Propagation system of loquatThree different propagation systems of loquat were compared, by shoot tip culture, immature embryo culture and mature embryo culture. In shoot tip culture, it was found that there were a low contamination ratio and a high survival ratio with about 75% in all the cultured materials disinfected with saturated bleaching powder for 20 minutes then 1 g-L-1 HgCl2_for 8 minutes. In this way the phenomenon of the tips' browning could be well avoided. The medium of MS+BA1.0 mg/L+NAA0.5 mg/L could well induce the germination of the plantlets. In the culture of the immature embryo and mature embryo, MS+BA2.0 mg/L+NAA0.5 mg/L was profitable for the germination of the seedlings and also arose the propagation ratio of the plantlets that germinated from axil buds. The plantlets were then transferred to the medium of MS+BA0.5 mg/L+NAA0.1-0.2 mg/L which with a reduced consistency of endocrine when they grew to some degree. In such medium the plantlets could propagate effectively and their roots could be well induced.2. Preservation in vitro of Loquat's germplasm at regulation temperatureIt was found that both the packing with white paper, then covered with polypropylene membrane and the packing with tinfoil paper were suitable for the germplasm preservation. As packing materials, cotton plug and rubber plug were obviously not suitable.Although lower intensity light may be good for the preservation of germplasm in vitro, when the light intensity was below 700 Lx the preservation in vitro results of loquat's germplasm were not as well as those of a higher light intensity.PP333, a kind of inhibitor, was in favour of the preservation in vitro of loquat's germplasm with the consistency scopes from 2 mg-L-1 to 5 mg-L-1. The existence of high consistency mannitol (>5 g-L-1) was harmful for the plantlets in vitro. CCC and ABA which also be used as inhibitors, for the preservation in vitro of loquat's germplasm, were found with suitable consistency of about 25 mg-L-1 and 10 mg-L-1 respectively.Of all the three inhibitors, PP333 was most suitable for the preservation in vitro of loquat's germplasm. Loquat's survival ratio was above 90% after being preserved for 8 months with PPaaa at the consistency of 5 mg-L-1.3. Preservation in vitro of Loquat's germplasm at low temperatureLow temperature was in favour of the preservation in vitro of loquat's germplasm. Almost all the species had pretty well effects of preservation at a low temperature of 11 ±0.5℃. The height of plantlets and the number of the leaves et al., which were as the statistic of the vital powers of preserved plantlets, were obviously below that of the check groups which preserved at the temperature of 25 + 1癈. And they were found having a high survival ratio of above 70% after being preserved in vitro for more than half a year. But it was also found that not every species preserved was adapt to this low temperature, Xiangtian, one species of loquat, being harmed at this temperature (11±1℃). This maybe mainly attributed to the different characteristics and cool-resistances of various species of loquat.4. Preliminary study of cryopreservation of Loquat's germplasmA procedure had been studied on cryopreservation of loquat pollen by the method of dry freezing. It indicated that the major factor that determined the cryopreserved loquat pollen longevity was its water content, the adequate water content for its survival was about 30%. The thaw temperature and methods after being cryopreserved were not significant to the percentage of stored pollen's germination in vitro. Staining and sprouting test indicated that the viability of cryopreserved pollen had littl...
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