‘Jinyan’, a kiwifruit cultivar selected and promoted by the Wuhan Botanical Garden, Chinese Academy of Sciences during the last decade, is one the most promising gold-fleshed cultivars for the south of China. It is thought to be an interspecific hybrid from the cross Actinidia eriantha as mother, with A. chinensis as father (Zhong et al., 2015). Many reports have shown that ‘Jinyan’ produces good crops of fruit, with attractive, gold-colored flesh. It is true that in vitro experiments by Wang et al. (2019) showed ‘Jinyan’ to be highly sensitive to kiwifruit canker disease, a bacterial disease that is fatal and destroys commercial kiwifruit orchards. But our own field trials in Gannan, Jiangxi and reports from Pujiang, Sichuan (W.B. Zhao, personal communication) indicate that ‘Jinyan’ is more tolerant of the disease than other cultivars widely planted in south China, such as ‘Hongyang’, a red-fleshed kiwifruit cultivar. In Pujiang County, Sichuan, 4000 ha of Jinyan have been planted, making it the most widespread gold-fleshed kiwifruit cultivar there. Considerable plantings have also been established in Jiangxi, Zhejiang, Hunan, and other provinces in the south of China.
However, the dry matter of the mature fruit from Fengxin County, Jiangxi is generally less than 16%, and this seriously affects fruit taste and flavor. Dry matter is an important index of fruit quality; it determines the fruit flavor and taste of Actinidia fruit when they are eating ripe (Burdon et al., 2004; Nardozza et al., 2011; Wu et al., 2013). Low dry matter eventually becomes a financial issue for kiwifruit growers, and the problem seriously affects the economics of kiwifruit orchards because of the dislike of customers of such inferior fruit (Jaeger et al., 2011; Wu, 2019).
Although there are many ways to improve dry matter (Patterson and Currie, 2019; Wu et al., 2012), there are only a few reports on how the method of pruning affects fruit quality (Miller et al., 2001; Patterson and Currie, 2011; Thorp et al., 2018). In addition, fertilization, exogenous hormones, moderate drought stress, and other methods can be used to improve the dry matter of fruit crops (Sale and Lyford, 1990; Wu, 2015; Wu et al., 2012). However, fruit growers prefer to use pruning, girdling, summer pruning, and so forth to control shoot growth and vegetative growth to achieve high fruit dry matter, fruit size, and desired crop load (Patterson and Currie, 2019; Wu, 2019), because such methods are safer, without potential chemical contamination, more effective, and have fewer adverse effects on both the vine and the environment.
In this study, a new summer canopy management methodology has been developed, in which the terminal parts of flowering shoots are twisted and squeezed before flowering, then removed after fruit set. Aspects of fruit quality such as flesh color, flavor, and taste of the fruit from treated shoots were evaluated and compared with controls. The aim was to provide a practical method to increase fruit dry matter, thereby allowing fruit quality to reach commercial requirements.
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