Studies On Dwarfing And Early High-yield Theory Of Gm256 Interstock For 'jinhong' Apple

Apple trees of'Jinhong'with dwarf interstock GM256 and rootstock Malus baccata (L.) Borkh. were used as materials in the experiment. Effect of interstock GM256 on dwarfing of'Jinhong'trees and pruning reaction of one-year-old tree were studied. This supplies theoretical and practical basis for raising yield and quality from biological and morphological aspects. Pruning techniques for early cropping were also proposed based on the study. Studies of factors related to high-yield at early age and theory were also carried out, which was of value to develop dwarf apple in Jilin province and cold area of northern China. The results of the study were as follows:1. Dwarf interstock GM256 has significant dwarfing effect on'Jinhong'apple trees. Hight of seven-years-old tree was reduced for 30% and total production was 3.55 times of the control. soluble solids increased and fruit color and quality improved.2. For production high quality'Jinhong'apple using GM256 as interstock, space in the rows between permanent trees should not less than 1.5m. Shoot and fruit ratio should be more than 2.5:1.If trees were planted at 2X 3.5 meters, proper load would be 15.5-18.0kg/tree for a high and steady yield of high-quality fruit.3. The pruning of one-year-old shoots should be slight for dwarf young'Jinhong' apple tree. Proper cutback (1/3 to 3/4 of the shoot remained) could increase total growth of this branch. Vegetative growth was enhanced and canopy enlarged, and amount of shoots and leaves increased.4. Shoots of young apple trees were topping when they were 30 cm in length, i.e., at the end of May to early of June in Jilin province. Flower and fruit thinning could be done in 30 days, from full bloom to physiological fruit drop. The most of two fruits could be left for each inflorescence, and the proper leaf-fruit ratio was 15-20:1.5. Dwarfing interstock GM256 could promote the reproductive growth of'Jinhong' apple. It was helpful in accumulation of assimilate and early bearing.