Superior Tree Selection Of Ziziphus Jujuba Cv. Jiaochengjunzao And Studies On Its Fruit Development

Based on the resources of the Ziziphus jujuba cv. Junzao in its natural distributed area Jiaocheng county, Shanxi province. 12 superior trees were selected by the methods of preliminary selection, secondary selection and final selection. Through the application of fuzzy mathematics comprehensively estimating optimization method, the tree No.3 was chosen as the best one and could be reproduced and extended. In addition, the pricipal component analysis shows that the basic indexes for a superior tree are: mean yield per area of crown shadow, rate of flesh weight to fruit weight, Vc content, sugar content.Two kinds of selected superior trees and the common fruit trees were used to explore the fruit development law and we have studied the variation taw of length, transverse diameter, fresh weight, sugar content, vitamin C and organic acid of the fruit and the variation law of Poly-phenol oxidase (PPO), Peroxidase (POD), superoxide dismutase (SOD) and Hydrogen Peroxidase (GAT) activity of the fruit and leaves in different fruit growth stage. We also compared four kinds of enzyme in the fruit with those in the leaves and analyzed the vitamin C and gross sugar with gray relationship. The results show: (1) the fruit growth curves of fresh weight, length and transverse diameter are all double "S" shape. (2) The Vc content is least in the stage of fruit setting, and then increases rapidly. Near the stage the fruit-stone is hardening the Vc content is highest and then decreases gradually. (3) The gross sugar content takes an increasing trend during the whole fruit growth stage. Before the stage the fruit is whitening the sugar is mainly composed of glueose and fructose, and the sucrose is high comparatively in the later growth stage. (4) The organic acid curves are low-high-low in the course of fruit development and the content reaches the highest in the fruit maturation. (5) The fruit SOD activity curves have one peak, and the activity is highest when the fruit-stone is hardening; the fruit PPO activity curves take a "W" shape and have two peaks on July 10th and August 9th; the fruit POD activity is highest and lowest respectively on July 10th and July 25th; the fruit CAT activity curves take a inverted "Z" shape and the activity reaches the highest on July 25th. The leaves SOD activity curves have one peak too, and the peak is formed on August 24th; the curves take double peak, inverted "Z" and one peak shape respectively for PPO, POD and CAT activity. Comparing the enzyme activity between the fruit and leaves shows that the enzyme activity in leaves are higher than those in the fruit. (6) During the whole fruit growth stage the order of relationship with Vc is: CAT>SOD>POD>PPO>fruit fresh weight>chlorophyll>organic acid, and the order of relationship with sugar is: fruit fresh weight>chlorophyll>organic acid>PPO>POD>SOD>CAT>Vc. This shows the fruit Vc content is related to the fruit resistance ability, and the fruit fresh weight, organic acid and chlorophyll relate to the accumulation of sugar greatly. In addition, the value of relationship shows the fruit sugar content is related to the fruit resistance ability too.