Study On Affecting Factors Of The Fruit Shape In 'Fuji' Apple

Fuji apple is the most important cultivar in China. The poor commodity quality was one of the problems in production, the lopsided fruits seriously affected the appearance quality and it was particularly serious in the Loess Plateau. With the purpose of resolving the lopsided fruits and improving the fruit quality, the experiment was conducted on 16～17 year old red Fuji apple trees (Malus domestica Borkh,cv Fuji) from 2009 to 2010 in the main producing area Baishui county of Shaanxi province. The experiment was systematic measurement the dynamic growth and development of Fuji apple, analysis the different cultivations, the different fruit branches, the different fruit ways affected on the fruit shape of Fuji apple, focused on the effects of the pollination and fertilization, the seed development on the fruit shape etc. The main results were as follows:1. In Shaanxi producing area, the vertical and the transverse diameter showed the same trend of the Fuji apple in the fruit growth period, and showed a single"S"type of growth curve. About 3 to 4 weeks after flowering, the fruit transverse diameter growth was always greater than the vertical diameter, from enlargement stage to harvest the transverse diameter was significantly greater than the vertical diameter.2. The cultivation measures had a certain influence on the lopsided fruits of Fuji apple. By comparison the Joe cultivation, the dwarfing cultivation and the short-branch cultivation, the skewed fruit rate of the short-branch cultivation was relatively lower than the Joe and the dwarfing cultivation, but the difference was not significant. In the different crown directions, the skewed fruit rate of east and south of tree crown were slightly lower than the west and north. In three fruit branches, the fruit shape index of the long fruit branch was significantly greater than the medium branch and the short branch, the fruit unsymmetrical index was smaller than the other fruit branches, but the difference was not significant. In the different fruit ways, the drooping fruits were symmetrical and less deformed fruits, and the obvious difference in the fruit shape arcsine with the lateral fruit.3. The pollination and fertilization was an important factor on the fruit shape of Fuji apple. Compared with the natural pollination, the artificial pollination could significantly reduce the fruit unsymmetrical index. By Qin guan, Gala, Pink Lady and Starkrimson pollination, the obviously differences in the fruit setting rate and the seed numbers, the effects of Pink Lady pollination was worse than the other three varieties. The pollen germination and pollen tube growth of four varieties were observed by fluorescence microscopy and found that in the compatibility with Fuji the four varieties had significantly difference, the better compatibility between Qin guan and Fuji, Gala and Starkrimson followed and the weaker compatibility between Pink Lady and Fuji. The fruit unsymmetrical index was high and the fruit were more deformed fruit after Pink Lady pollination, but the other three varieties pollination could significantly improve the fruit shape. The number of stigmas had significant effect on the fruit shape of Fuji apple, removed 3～4 stigmas could obviously reduce the seeds and lead to develop into the deformed fruit.4. The seed development was closely related to the fruit shape. The mean seed numbers was 7.6 and distribution in each ventricle in the symmetrical fruit, the mean seed numbers was 6.7 and at least one ventricle of seed was abortion in the unsymmetrical fruit, the mean seed numbers was only 4.0 and at least two ventricles of seed were abortion in the deformed fruit.5. The survey found that the ratio of the symmetrical fruit (the fruit unsymmetrical index DD≤O.15)was only 10% in the orchard of Weibei, the ratio of the unsymmetrical fruit(0.15<DD≤0.35) was 60%, the ratio of the deformed fruit(DD>0.35)was 30%.