Phenotypic and Phytochemical Variations in Wolfberry Varieties and Their Harvest Times

Lycium barbarum L. is a perennial deciduous shrub used for centuries as a traditional medicinal and food supplement in China. In this study, we investigated the effects of variety and harvest time on the phenotypic and phytochemical variations in goji berry fruits to optimize harvest strategies, select superior goji varieties, and improve market competitiveness of the goji industry. Both field investigations and laboratory analyses were conducted to evaluate yield, phenotypic traits, and nutritional indicators during the summer and autumn of 2024. Both variety and harvest time significantly affected most traits investigated, with strong interaction effects. Overall, summer-harvested fruits, which account for 78% to 100% of the total production per plant, had higher contents of Lycium barbarum polysaccharides and carotenoids than those harvested in autumn. A comprehensive evaluation using the TOPSIS method demonstrated that the fruits harvested in early July generally exhibited superior overall quality. Among the tested varieties, the ‘5-6’ variety consistently displayed outstanding fruit quality across all harvest times and showed very good prospects for application and extension in commercial production when compared to the other varieties. Our findings not only provide valuable insights into the comprehensive evaluations of different goji berry varieties but also highlight the importance of identifying optimal harvest times based on the sensory quality and nutritional value for each goji variety.