[Effects of environmental factors at different altitudes on leaves and fruit quality of Fuji apple]

To inquire the different performances of the leaves and fruit quality of Fuji apple tress at various altitudes and their responses to the environmental factors, indices including leaf morphology, anatomy, δ13 C, and fruit quality of the Fuji apple trees at respective altitudes of 1375 m, 1575 m and 1715 m were investigated and their responses to environmental factors were determined following stepwise regression analysis. The results showed that 6 factors like the warmth index, Bailey's index, photosynthetically active radiation (PAR), coldness index, ultraviolet B and the annual precipitation dominantly affected the characteristic parameters of leaves and fruit. Elevation increase was matched by the decreasing warmth index, rising Bailey' s index, intenser PAR, higher coldness index, stronger ultraviolet B and heavier annual precipitation; meanwhile, the leaf structure and fruit quality parameters also displayed evident trends of change accordingly, namely, leaf parameters like leaf thickness, cuticle thickness, ratio of palisade and spongy, maximum conduit diameter, δ13C and nitrogen content per unit area increased gradually, and oppositely, leaf length-width ratio, specific leaf area, stoma length-width ratio and ratio of upper and lower epidermis to the leaf thickness decreased gradually; similarly, fruit parameters such as fruit shape index, fruit hardness, sugar-acid ratio, total color and the a/b-value ascended while the titratable acid and the hue angle descended. With increasing the altitude, the photosynthetic rate and water use efficiency of leaves were enhanced, and the fruit sugar-acid ratio climbed and the fruit flavor and color improved. Therefore, it could be safely concluded that within the altitude range between 1375 and 1715 m, environmental factors at a higher altitude favored Fuji apple growth.