Influence of light-reflecting mulching sheet and shading net on ascorbic acid content in blackcurrant fruits (Ribes nigrum)

Blackcurrant (Ribes nigrum) is well known for its human health benefits. The nutritional properties of fruits are occasionally affected by insolation conditions. So, we examined the effects of light quantity on the nutritional value of blackcurrant fruits cultivated in a relatively low latitude area (latitude 35°25’N, longitude 139°20’E). The ‘Radiant’ and ‘Nevis’ cultivars were mulched using a light-reflecting sheet and cultivated under a shading net. The amount of cumulative light received by the fruit clusters was significantly increased under mulching compared with that of the unmulched control fruits. However, the amount of light had negligible effects on ascorbic acid content or antioxidant capacity. Cultivation under shading net decreased the ascorbic acid content in ‘Radiant’ fruits by 13-16% compared with that in the unshaded control. In contrast, the ascorbic acid content in ‘Nevis’ fruits was not affected by shading. These results indicate that mulching using light-reflecting sheets provides little benefit, and that cultivation under a shading net has negative effects on the nutritional quality of blackcurrant fruits, depending on the cultivar.