Studies On Juvenile Characteristics And Genetic Trends Related With Photosynthesis Of Apple Hybrid Seedling

Most fruit trees have long juvenile period. Therefore, shortening juvenile period is very important in improving the breeding efficiency. We study on the leaves characteristics of hybrid seedlings during pre-period growth to know their characteristics. It also provides theory base for shortening juvenile period, pre-choice and early fruiting. On the other hand, there is strong relativity between photosynthesis in fruit tree and its parents inherit characteristics. This paper compare parent to hybrid of apple in photosynthesis functions to make reference for high photosynthesis breeding. The results showed:1.With the growth of hybrid seedlings from juvenile period to adult period, regular changes has appeared in leaf shape. Areas of leaves enlarge. There are obvious differences between the two combinations of JinhongxNagafu2and Nagafu2×Jinhong.However, there are less visible differences between the combinations of LiaofuxMolie’s Delicious and HanfuxHuaguan; Leaves get thick. There are extremely differences between the combinations of LiaofuxMolie’s Delicious and HanfuxHuaguan, but there are not obvious differences between the combinations of JinhongxNagafu2and Nagafu2xJinhong; The SPAD value of Chlorophyll content enlarge and the four combinations all reach the obvious level of differences; The dry weight of leaves also increase, the combinations of LiaofuxMolie’s Delicious are very obvious differences, the combinations of HanfuxHuaguan differently obvious and the combinations of JinhongxNagafu2and HanfuxHuaguan are differently less visible.2. It is a key effect factor that the increasing of protein contents and soluble sugar contents for apple hybrid seeding from juvenile period to adult period. It also closely connected with seedlings height.3. Contents of four kind plant inner hormones (GA, IAA, ABA, ZT) in adult seedlings have similar change trends. Compared adult-zone with juvenile-zone of the most combinations, the contents of GA descends and the contents of IAA, ABA, ZT increase. It indicates that the fall of GA is good for blooming and the increase of ABA may improve the formation of floral buds. The high contents of IAA, ZT be propitious to the formation of floral buds. For1-year-old hybrid seedling, the contents of ABA, IAA in the same plant increase with the rise of leaf height. The contents of GA, ZT appear falling trends with plant height increase in different height seedlings’top leaf and the contents of IAA appear rising trends.4. The Chlorophyll content in apple leaves was quantitative traits controlled by polygene. Their inheritance showed mainly additive genetic effect and non-additive effect was weaker. The studies suggested that choosing parent with high Chlorophyll content was very important to improve photosynthetic performance in seedlings.5. The hybrid of HuahongxHanfu combinations was higher in photosynthetic rate and stronger ability to assimilate CO2and higher yields characters than their parents; Hybrid seedlings can assimilate more CO2when consumed equal water, which has relatively higher water use efficiency than their parent. All information above suggested that the seedlings have obvious hybrid advantages in photosynthetic efficiency. However, whether there is the same result in hybrid of different combinations and during different periods still need further research.