The Effects of Tree Growth Forms on the Photosynthetic Activity and Fruit Quality of ‘Korla Fragrant’ Pear

‘Korla fragrant’ pear has a long history of cultivation in Xinjiang, China, with favorable economic and social benefits. The selection of tree growth has a direct impact on improvements in fruit yield and quality. In order to provide a theoretical basis for the efficient and high-quality cultivation of ‘Korla fragrant’ pear, two ‘Korla fragrant’ pear tree growth forms, namely trunk shape and small-canopy shape, were selected as experimental materials to study the differences in the parameters of different tree growth forms, as well as the effect on photosynthetic activity and fruit quality. The results show that the small-canopy-shape trees exhibited significantly improved photosynthetic activity, with a 60.64% higher net photosynthetic rate (Pn) in the upper canopy compared to the trunk-shape trees. Fruit quality was also superior in the small-canopy-shape trees, with increases in single-fruit weight (29.36–46.91%), soluble solids content (13.51–14.39%), soluble sugar content (25.79–27.56%), and vitamin C content (up to 0.4363 mg·100 g−1 in the upper layer). However, the yield per unit area of the trunk-shape trees was significantly higher than that of the small-canopy-shape trees by 19.32% because of the higher number of short fruit branches and increased prevalence of smaller row spacing. In addition, within the same tree growth forms, photosynthetic activity and fruit quality were improved in the upper layers compared to the lower layers.