A One-Month-Delayed Secondary Harvest Induced by Pre-Flowering Shoot Tipping Improves Yield and Quality of ‘Chunguang’ Grape Under Protected Cultivation in Northern China

Protected cultivation ensures stable conditions for premium table grape production but involves high initial costs. A double-cropping system enabling a delayed secondary harvest within a single season may increase yield and accelerate cost recovery, yet the characteristics of the secondary harvest remain poorly understood. In the paper, we compared the fruit quality of FH (first harvest) and SH (second harvest) of the early-ripening cultivar ‘Chunguang’ produced in northern China. The results showed that the SH contributed to a 23.9% increase in total yield. SH berries were smaller, with a mean weight of 6.7 g, and exhibited darker skins, higher anthocyanin content (11 mg g−1 fresh skin), higher seed number, higher accumulated sugar components, and 4.55 mg L−1 of titratable acids. This study provides the first evidence that a secondary harvesting system under protected cultivation can simultaneously enhance yield and fruit quality in northern grape-growing regions.