A Study Of Physiology And Biochemistry On Germplasm Preservation In Vitro Of Loquat (Eriobotrya Japonica Lindl.)

This study explored the germplasm resources preservation and Physiology and Biochemistry of loquat ( Erilbotrya japonica Lind I ) in vitro. It included the establishing of rapid propagation system, Physiology and Biochemistry of limiting the growth with normal temperature and low temperature , Cryopreservation of loquat pollens, dehydrogenase activity of excised embryos of loquat.1. Rapid propagation system of loquatTwo different rapid propagation system of loquat were compared by shoot tip culture, immature embryo culture. In shoot tip culture, it was important to use the saturated bleaching powder to preceding treat and choose the appropriate size explant for avoiding browning. The medium of BA1.0mg/l+NAAO. 5mg/l can increase shoot tip growth effectively. In immature embryo culture, the medium MS+6-BA2.0mg/l+IAAO. 5mg/ lcan promote sprouting effectively. Moreover, when using the medium MS+ BA1.0mg/l+ the NAA0.2mg/l, the buds were higher and grew better, so this medium was the most suitable to multiplication.2. Physiology and biochemistry study of limiting the growth in normal temperature and low temperature preservationPreservation of Loquat used MS medium. In low temperature (11 ± 1 ℃) medium was added cane sugar 2. 5%, agar 0. 75% , in normal temperature for limiting growth the medium was added plant growth depressant PP333 5 mg/l, agar 0. 75%, the cane sugar was 2. 5% and 5% respectively. It is hope to understand the effects of cane sugar and temperature on the seedlings of loquat.In six months preservation of loquat, respiratory rate, chlorophyll, soluble protein, PPO activity and POD activity were determined. They had relation to plant adverse circumstances physiology and metabolic adjustment. It was shown that respiratory rate of the loquat plantlets was lower with preservation time prolonged; Chlorophyll attained the highest value in the third month and declined then; The soluble protein content was related to preservation temperature and cane sugar concentration, it increased before descending or made a slow descent; The PPO activity declined the trend after rising first, the temperature as to its activity influence was bigger, but the cane sugar smaller; the activity of the POD was to descend the trend , however cane sugar as to its influence was bigger, and temperature was smaller .3. Cryopreservation of loquat pollensDehydrated loquat pollens with different water content were stored in super-low temperature(-196℃) .The results indicated that the survival rate of pollen preservated in LN was related to water content. For the loquat, 12. 9% pollen water content was appropriate. The pollens were preserved in LN for 2 h, 8 h, 24 h, its germination rate had no obvious difference than before preservation. 4. Dehydrogenase activity study of excised embryo of loquatThe young embryos were treated with vitrification protector, then preservated in LN. After thawing, dehydrogenase activity was determined. The result showed that the water content of excised embryo was important factor to affect loquat cryopreservation. In excised embryo with 15% and 20% water content the TTCH activity was high, it can conserve and maintenance the excised embryo vitality. At cryopreservation the effect of freezing speed on dehydrogenase activity was smaller, but the effect of thawing was bigger.