| The main purpose of this study is to discuss the relationship between relative light radiation intensity distribution and the fruit quality and output within three canopy shapes of "Fuji apple", the three canopy shapes are the high stem and open center shape, the small and sparse canopy shape and the spindle shape. The result show the ecological mechanism that the high stem and open center shape is superior to the small and sparse canopy shape and the spindle shape in all sides, especially its effects in increasing production and economy benefits are marked. This study provides theoretic base and instructively technical measures for reconstructing tree shape in heighten and denser planted orchards, cultivating reasonable population structure, improving fruit quality, maintaining continually high quality and fertility of orchards. From this experiment we can obtain the following conclusions:(1) The high stem and open center shape is characteristics for fewer main branches, reasonable composing of twigs and open frame of tree body. (2) The light radiation intensity distribution within canopy is relative equilibrium, it also increase gradually from bottom to top and inner to outer of canopy, which is highest in outer and lowest in bottom closed to trunk. The proportion of it more than 30% of relative light radiation intensity in tree body is not only higher, but uniform in every layer. The relative light radiation intensity distribution is positively correlated with corresponding crown layers in trees. There are fewer invalidated light radiation sections within crowns, where the relative light radiation intensity is lower than 30%. The sections where the relative light radiation intensity is more than 40% account for 70% of the area of whole crown. (3) The photosynthetic capacity of different kinds of twigs and leaves at different positions is notably different. Due to having fewer total quantity of twigs and enough light radiation in crowns, the high stem and open center shape has obviously higher photosynthetic capacity of leaves than the small and sparse canopy shape and the spindle shape.(4) Pigmentation area(F=2784.53**＞F0.01), rigidity(F=26.52**＞F0.01), content of soluble substance(F=1.48**＞F0.01), single weight of fruit(F=101.31**＞F0.01), and titratable acidity(F=157.98**＞F0.01) are strongly, notably and positively correlated with the light radiation intensity distribution. The high stem and open center shape can notably increase the output of apple (45.45kg/tree), and make the fruit distribute in top and middle parts of trees, where the light radiation is enough. The ratio of fruit with high quality of this tree shape (63%) is obviously higher than the small and sparse canopy shape (54%) and the spindle shape (51%).(5) It can improve light radiation in bottom to lay reflector membrane, particularly in the high stem and open center shape, which has a good character for light to permeate(the relative light radiation intensity of lower layer is boosted 50%). However, the crown is much closer in the other two kinds of shape, so the effect in them is not obvious. At the same time, picking leaves and turning around fruit can notably improve apparent quality of fruit (the proportion of fully red apple in lower layer is increased 192% compared to CK).(6) The result of this experiment shows that the quality of fruit has a strongly and notably positive correlation with the relative light radiation intensity. The best range of the relative light radiation intensity for single weight is from 30% to 100%, in which the best value is 36%; for rigidity of fruit, 30%～100%, the best value, 73%; for content of solubility substance, 34%～100%, the best value, 82%; for pigmentation area, 40%～100%, the best value, 36%. When the relative light radiation intensity is more than 80%, pigmentation area of fruit increases no longer, and the sunstroke fruit are formed easily. In general, the best range of the relative light radiation intensity in crowns is 40%～80%.
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