Abstract: This paper studied the effects of different pruning modes on the light distribution at different positions of canopy and the fruit yield and quality in different layers in a densely planted ‘Red Fuji’ apple orchard. Comparing with no pruning, both light and heavy pruning improved the light distribution in the canopy. Under light pruning, the canopy volume with a relative light intensity less than 30% occupied 14.6% of the total, and that with a relative light intensity more than 80% accounted for 11.2%. Under heavy pruning, the two values were 12.8% and 28.8%, respectively. The fruit yield under light pruning increased in the first year, but that under heavy pruning decreased, with the fruit quality being both improved. The mean fruit mass, firmness, and soluble solid matter content decreased in the order of light pruning > heavy pruning > no pruning, the titratable acid content was in adverse, and the anthocyanin content was in the order of heavy pruning > light pruning > no pruning. From the viewpoint of fruit yield and quality, light pruning was the best modification mode for densely planted orchards.

Key words: ‘Red Fuji&rsquo, apple, modification of densely planted orchard, fruit quality, cold-shock, tomato seedling, high temperature stress, dwarfing effect, ethylene production, GA₃.