| Nowadays, nectarine is the main project of peach producing and breeding, and studies on nectarine biological characteristics and increasing germinating rate of early ripening hybrid nectarine can make progress in variety improvement and nectarine production. So following experiment was carried on: (1) With "Beijing No. 8" as control, fruit growth and Fruit-drop curve of nectarine "Qin Guang" was observated, at the same time, with electron microscope scanning, fruit cell structure was observed. (2) Effect of some plant hormones on seed dormancy and seedling growth were studied with hybrid nectarine, P. davidan, P. kansuensis, P. ameniaca and P. Mahaleb. (3) To increase germinating rate, several factors affected embryo rescue such as culture mediums, time of low temperature treatment, kinds and concentration of hormones and methods of transplant were selected. The results are as follow: 1. The differences between "Beijing No. 8" and nectarine "Qin Guang" on fruit growth and Fruit-drop curve(1) The research showed that the fruit growth curve of nectarine "Qin Guang" is similar to that of peach "Beijing No. 8". They have three period of fruit growth, the difference is that the fruit growth of nectarine "Qin Guang" continued in the hardening stone period.(2) Fruit-drop of nectarine "Qin Guang" is very heavy in hardening stone period and that is related with "Qin Guang" continuing growth in that period.2. Fruit surface tissue, skin and flesh cell structure of nectarine have close relation to the fruit cracking (1) There is dense fine hair on the peach fruit surface, while there are little wave-like cracks on the nectarine surface besides stoma. With the fruit growth the cracks become more and more obviously, if it happens to environment stress the fruit is going to splitting. (2) Peach fruits have thick skin cell with solid structure and small gap between cell, nectarine fruits have thin skin cell with loose structure and big space between cell, so nectarine splitting easily. (3) Nectarine flesh cell grow more rapid than that of peach, also. This situation leads to the expand pressure produced by fruit is bigger than tensile stress that fruit can stand for, so fruit cracking appear.3. Promaline and GA3 can promote seed germination of peaches, apricots and Mahaleb cherry3.0μg.g-1 Promaline and 0.5μg.g-1 GA3 had most significant effect on seed dormancy and seedling growth. Germination percent could decrease with low concentration treated, while seedlings could not grow well with high concentration treated of Promaline and GA3. 1.0-5.0μg.g-1 Promaline could increase seed germination percent of Mahaleb cherries after the seeds were stratified and the concentration of 3.0μg.g-1 was most effective. GA3 and BA had not significant effect on seed dormancy of Mahaleb cherries.4. Established a series of early ripping embryo culture technology to increase the seedling production Several culture mediums were used to rescue embryos of early ripening nectarine and one of those, WPM showed the best results. The germination percentage was the highest, 95.56% when WPM was used as the culture medium. Different cultivars required different time of low temperature treatment, the earlier the cultivars ripened and the longer time they needed. 1mg/L 6-BA + 0.2mg/L IBA + 0.1mg/L GA3 broke embryo dormancy of nectarine effectively, and seedlings from treated embryos grew well. pH in medium was better from 5.7 to 6.3, and the early ripening cultivars needed relatively higher pH in medium for embryo rescue. Plastic cups were used to cover the seedlings from embryo rescue in the daytime and cups were removed at night to last for 5 to 7 days for training the seedlings. Fungicide was sprayed into the soil every 3 days, the rotten cotyledons were removed in time. With the methods above, survival percentage of the rescued seedlings could increase.
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