Studies On In Vitro Conservation Of Some Diospyros Germplasm By Modified Droplet Vitrification

China is one of the primary origins of Diospyros spp., and there are abundance plant resource. However, planting in open field, as a traditional method for conservation of persimmon germplasm, has emerged so many faults such as diseases and insect pests, natural disasters. So it is important to establish the corollary equipment of in vitro conservation. Cryopreservation is considered as an ideal method for long-term base storage of germplasm. The procedure of cryopreservation was studied using in vitro culture and dormant bud in different genotypes of some Diospyros spp. as materials. And, the major results listed as follows:1. Comparison of the effect of CTK such as TDZ,ZT and CPPU on the proliferation of plantlets. The result proved that TDZ can shorten the period of culturing by applying it in dormant shoot-tips of five genetypes of Diospyros spp. including Date plum, 'Mopanshi', 'Eshi 1', 'Zenjimaru', 'Maegawa-jirou', After 2 weeks, the proliferation rate exceed 60.00%.2 Comparison of the effect of the three different cryopreservation protocols which were vitrification, the droplet vitrification and the modified droplet vitrification, the survival rate of cryopreserved in vitro shoot-tips of Diospyros spp. including common persimmon, 'Eshi 1', 'Youhou' was respectively 33.33%, 37.78%, 57.78%.3. An approach for cryopreservation of in vitro shoot-tips of some Diospyros spp. was established by the modified droplet vitrification. The result indicated that shoot-tips of in vitro axillary precultured on MS (1/2N) medium supplemented with 0.5mol/L sucrose for 5 days. which were derived from cold-hardened shoots on MS (1/2N) medium at alternating temperatures 25℃with 12h light/4℃12h dark. Combined with short or no photoperiod, which were loaded in loading solution for 20 min at 20℃, and incubated in PVS2 for 1.5h at 0℃prior to direct plunge into liquid nitrogen. After rapid thawing at 40℃warm water bath and rinsed, the shoot-tips were plated on the regeneration medium. In result, the survival of shoot-tips exceeded 60.00%.4. A procedure had been studied on cryopreservation of 5 genetypes including Date plum, 'Mopanshi', 'Eshi 1', 'Zenjimaru', 'Maekawa-Jirou' of dormant shoot-tips of persimmon by the modified droplet vitrification: Shoot-tips were precultured on the MS (1/2N) medium supplemented with sucrose concentrations of 0.5 mol/L for 2 days, were loaded with the MS (1/2N) medium supplemented with 2 mol/L glycerol and 0.4mol/L sucrose for 10 min at 20℃, and incubated in PVS₂ for 1.5h at 0℃prior to direct plunge into liquid nitrogen. After rapid thawing and rinsed, the shoot-tips were plated on the regeneration medium and culture. And the regeneration rate was up to 66.67%.