Effects Of Branch Bending On Characteristics Of Transportation And Distribution Of ¹³C And ¹⁵N For Malus Hupehensis Rehd

Branch bending has been one of the common techniques used in fruit tree pruning, and it is commonly used in the high-spindle and dwarf rootstock apple orchards. Branch bending can increase the branch opening angle, apical dominance of fruit trees has been reduced,which also can improve the light and ventilation conditions inside the tree. Branch bending have had the effect on the transport and distribution of nutrients in the tree body, the accumulation of carbohydrates in fruit trees bud increased have promoted, so as to promote fruit bud differentiation. Branch bending have been the effective measures to solve the difficult problem of bud formation of Fuji apple in the Loess Plateau region.The three-year-old Malus hupehensis Rehd rootstock of Malus domestica was used to study the effects of different branch bending on the 13 C and 15 N absorption, transportation and distribution with carbon and nitrogen isotope tracer method in the Yangling Demonstration Nursery of national apple industry technology system of modern agriculture demonstration garden in Shaanxi Province in 2015. The results showed that with the increase of branch bending, distribution rate of 13 C increased in leaves, main branch, spur terminals,long-medium shoot terminals and shoots on May 20, and on June 20 and August 20 in these parts of Malus hupehensis Rehd tree distribution rate of 13 C at 90 ° treatment was significantly higher than other treatments, distribution rate of 13 C of truck up labelling branch increased,while distribution rate of13 C of truck down labelling branch, small roots and big roots reduced. The photosynthesis products transported down had been reduced, the amount of storage capacity of photosynthesis in leaves and branches increased. After fertilizer(15NH4)2SO4 was applied in spring, with the increase of branch bending, Utilization rate of15 N in leaves, main branch, spur terminals,long-medium shoot terminals, shoots, truck, small roots and big roots had been a decrease. Utilization rate of 15 N in the Malus hupehensis Rehd increased first and then decreased, which is higher than other treatments at 70° bending branch. Rate of ‘15N’ to total 15 N uptake in the main branches, long-medium shoot terminals,shoots, truck and small roots of Malus hupehensis Rehd reduced, Rate of ‘15N’ to total 15 N uptake in the leaves, spur terminals and big roots increased. Therefore, with the increasing of branch bending, the transportation-distribution of photosynthetic to root had reduced, thegrowth of root had been slowed down, which could affect the absorption of nitrogen nutrient,that have regulation on the growth of young trees, that had been beneficial to differentiation of flower bud and fruition of the fruit trees. While with the reducing of branch bending, the transportation of photosynthetic to root had been increased, the growth of root in Malus hupehensis Rehd had been promoted.