The Effects Of Double-rootstock On Grouth And Development Of Young Apple Tree In Arid Areas

China is the world’s largest producer of apples and dwarfing and closing planting mode is an effective measure to promote the apple industry development of northwest Loess Plateau. There are many problems in using of interstocks because of the limitations of natural conditions. This article will do research about the effects of T337-Malus prunifolia(Willd) Borkh rootstocks on growth and development of young apple trees to explore the production capacity and adaptability of double-rootstock. The research result will have significance for theoretical and practical of apple rootstock in arid regions.Experiment materials were young apple trees of “No.2changfu” grafted on Malus prunifolia(Willd) Borkh and T337 one scion two root grafting system, young apple trees of “No.2changfu” grafted on T337 and young apple trees of “No.2changfu” grafted on Malus prunifolia(Willd) Borkh as control. Materials were measured by appropriate ways. Researching on the effects of T337-Malus prunifolia(Willd) Borkh rootstock on young apple trees’ growth and development was done by measuring sapling tree form, branch structure and composition, leaf morphology physiology, photosynthesis case and flower formation. The results are as follows:1. Double-rootstock has significant effect on trees’ dwarfing. The height and trunk diameter of double-rootstock young apple trees were significantly smaller than Malus prunifolia(Willd) Borkh young apple trees and the inhibition on height of double rootstock is stronger than T337. The trunk diameter of double-rootstock was bigger than T337 and the ratio of top shoot length with height was lowest.2. Double-rootstock has significant effect on inhibiting elongation and thickness of branches. The branch length, proportion of long sticks, branches thick, internode length of double-rootstock young apple trees were significantly lower than the T337 and Malus prunifolia(Willd) Borkh while having higher branch number and short branch proportion. The double-rootstock’s ratio of wood/cortex was significantly reduced compared with Malus prunifolia(Willd) Borkh.3. The leaf area and width of double-rootstock were significantly lower than the controls. Double-rootstock’s specific leaf weight and chlorophyll content were lower than T337 dwarfing young apple trees and the amount of organic synthesis was low.4. The Pn, Gs, Ci, Tr of double-rootstock young apple trees were significantly lower than T337. This reduced its photosynthetic capacity and organic matter accumulation. The WUEi of double-rootstock was higher than T337 but lower than Malus prunifolia(Willd) Borkh. Double-rootstock young apple trees have stronger adaptability to arid areas.5. Flower bud formation indicate that inflorescence number and flowering plant ratio of different rootstock young apple trees had an order of T337>double-rootstock>Malus prunifolia(Willd) Borkh. Double-rootstock young apple trees’ inflorescence number and flowering plant ratio were substantially higher than Malus prunifolia(Willd) Borkh, Double-rootstock young apple trees have earlier florescence and higher flowering ability.