Yield and fruit size are under the control of many interacting factors and crop failures can be caused by climatic extremes and poor flowering. Nevertheless, this study has shown that mulching, through the creation of improved soil properties and reduced environmental stress, has the potential to substantially increase A. arguta fruit size and yield. The mulched site performed better than the site without mulch in reducing soil temperature, increasing soil moisture and controlling available phosphorus. Moreover, mulching improved both yield and fruit size. In light of this, we hope that the results of our research will provide useful information for the cultivation of A. arguta in South Korea. However, it also seems necessary to conduct research on the use of different types of mulch and on the economic profitability of mulch in the future.

Soil properties are important environmental conditions affecting fruit quality and yield in new cultivars of Actinidia arguta. The yield of three A. arguta cultivars (cv. Autumn Sense, cv. Chungsan, and cv. Greenball) from Wonju city, South Korea was investigated from 2017 to 2019 and the relationships to soil properties are discussed. The yield of cv. Autumn Sense, cv. Chungsan, and cv. Greenball fruits ranged from 6.8 to 24.5, 14.0 to 29.0, and 10.5 to 38.5 kg/vine. cv. Autumn Sense had the highest soil organic matter content and soil C/N ratio over the three-year period. The yield of A. arguta fruits was positively correlated with soil C/N ratio and could be described by a power model (y = axb), suggesting that soil C/N ratio plays an important role in limiting the bioavailability and bioaccumulation of organic matter in A. arguta fruits. In addition, C/N ratio in the soil was influenced by the soil available phosphate. However, the threshold of the C/N ratio for A. arguta fruit differed according to cultivar, and especially the lowest threshold was observed in cv. Chungsan. Therefore, the application of an appropriate C/N ratio depending on the cultivar is required for improved fruit yield. Our results present the soil properties required to increase the yield of the new A. arguta cultivars in South Korea.