Effects of Different Shaping Methods and Loading on Fruit Quality and Volatile Compounds in 'Beibinghong' Grapes

The effects of different shaping methods and loading treatments on the photosynthetic rate, chlorophyll content, fruit yield and quality, and volatile compound composition of the 'Beibinghong' grape were studied. In the experiment, 6-year-old 'Beibinghong' grapes were selected as the material, and two kinds of shaping methods were adopted: the double main vine upright tree (control) and the inclined horizontal dragon tree. The inclined horizontal dragon tree was treated with different loads. The volatile components in grapes were analyzed by gas chromatography-mass spectrometry (GC-MS). The changes in quality and volatile components of 'Beibinghong' grape under different treatments were analyzed by multivariate statistics. The results showed that the inclined horizontal dragon tree significantly increased the net photosynthetic rate and chlorophyll content of leaves, and increased the soluble sugar content and sugar-acid ratio of fruits. The quality of grapes was better than that of the upright tree with double main vine. The results of loading showed that the plants with nine fruit branches had higher net photosynthetic rate and yield, and the best performance in reducing sugar content, titrable acid content and sugar-acid ratio, which was the most suitable loading treatment. The results of metabolomics study showed that 291 volatile metabolites were identified, of which 25 were considered to be the key differential metabolites affecting the flavor of 'Beibing red' fruit under different treatments. Further analysis showed that the inclined horizontal draconite tree was superior to the double main draconite tree in improving fruit quality and accumulation of volatile compounds in fruit. This study revealed the regulation mechanism of different shaping methods and loading loads on the growth and fruit quality of 'Beibinghong' grapes, which provided theoretical support for optimizing the viticulture management of 'Beibinghong' and improving the fruit quality and market competitiveness.