High-quality off-season mulberry fruit (Morus laevigata Wall.) induced by summer pruning

The growing recognition of mulberries as a potent source of bioactive and nutritional compounds, coupled with their increasing global consumption, underscores the need for efficient off-season cultivation. This study explores the influence of both in-season and off-season cultivation on the yield, bioactive components, and antioxidant activity of ‘Taiwan Changguosang’ (Morus laevigata Wall.) in a greenhouse setting. Despite the lower fruit yield during the off-season, the off-season fruit exhibits higher levels of bioactive compounds, including total anthocyanins, polyphenols, and flavonoids compared to its in-season counterpart. Additionally, the off-season fruit demonstrates enhanced DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging and FRAP (ferric-reducing antioxidant power), attributed to climatic conditions during fruit development, particularly air temperature and solar radiation. Moreover, the off-season fruit proves to be more palatable, showcasing a favorable balance between sugar and acid. Principal Component Analysis (PCA) and correlation analysis revealed a close association between antioxidant activity and the chemical contents of total polyphenols and flavonoids. This study underscores the feasibility and benefits of off-season cultivation for enhancing the nutritional profile and antioxidant potential of mulberries, providing valuable insights for optimizing cultivation practices.