Analysis of quality differences among six plumcot varieties during low-temperature storage and selection of storage-tolerant cultivars

【Objective】As a perennial deciduous fruit tree species, plumcot (Prunus domestica × armeniaca) exhibits significant physiological fruit drop during the maturation period, which substantially reduces marketable fruit yield. During harvesting operations, the lack of mechanized harvesting equipment and standardized operational procedures leads to prevalent mechanical damage to fruits, including surface abrasions and flesh bruising. Furthermore, infestations by various fruit tree pests and diseases further exacerbate both yield losses and quality deterioration. Postharvest physiological activities, including accelerated respiration and ongoing ripening processes, coupled with improper bulk storage practices, lead to significant fruit decay, quality deterioration, and substantial postharvest losses. Optimal low-temperature storage conditions can effectively delay fruit senescence and decay, activate the antioxidant defense system, and extend storage duration. Monitoring physiological indices associated with fruit quality provides comprehensive insights into the physiological responses to ambient temperature fluctuations during storage. This study investigated six plumcot cultivars including Weidi, Fengweimeigui, Weiwang, Fengweihuanghou, Konglongdan and Weihou to evaluate their physiological and phenotypic changes under low-temperature storage for identifying the most storage-tolerant varieties.【Methods】The storage experiment was conducted at the Jiamu Experimental Station in Wensu County, Aksu Prefecture, Xinjiang, starting in June 2024, using fruits from the plumcot germplasm resource nursery as test materials. Fruit maturity was determined by measuring firmness, soluble solids content (SSC), and color index using a GY-4 fruit firmness tester and an NK-55T handheld digital refractometer. Maturity standards were established based on the typical characteristic reference ranges for each cultivar at commercial maturity under optimal cultivation conditions, reflecting their general ripening performance. The harvest index ranges were determined through comprehensive analysis of our research group’s preliminary results, multi-year observational data, and industry standards. Fruits were stored at (4±1) ℃ for 45 days with four sampling time points (0, 15, 30, and 45 days). Quality parameters were measured at each interval, their correlations were analyzed, and a comprehensive evaluation model was constructed using principal component analysis. Fruit samples from six plumcot cultivars were collected between June and November 2024.【Results】At the onset of storage, the single fruit mass of six plumcot cultivars followed this order: Weidi＞Weihou＞Fengweihuanghou＞Konglongdan＞Fengweimeigui＞Weiwang. After 45 days of storage, the firmness reduction rates were: Konglongdan (80% ), Fengweimeigui (75% ), Weidi (68% ), Fengweihuanghou (64% ), Weihou (50% ), and Weiwang (47% ). The total acid (TA) content decreased by Weiwang (66.10% ), Weihou (63.04% ), Fengweihuanghou (51.92%), Weidi (51.72%), Fengweimeigui (38.16%), and Konglongdan (35.21%). The total sugar (TS) dynamics showed Weidi, Weihou, Fengweimeigui, and Fengweihuanghou peaked at storage end (12.82%, 11.94%, 9.66%, and 8.98%, respectively), increasing by 17.12%, 21.90%, 36.94%, and 1.17% from initial values. Konglongdan and Weiwang peaked at day 30 (9.49% and 9.05%, respectively), with 1.88% and 29.84% increases. Throughout storage, water content and soluble solid content (SSC) showed minor fluctuations. Four cultivars of Fengweimeigui, Weiwang, Fengweihuanghou, and Konglongdan maintained above 85% water content, while Weidi and Weihou ranged from 76.81% to 81.72%. Weidi and Weihou consistently exhibited higher SSC levels. Initial water contents of six plumcot varieties followed: Weiwang＞Konglongdan＞Fengweihuanghou＞Fengweimeigui＞Weidi＞Weihou. Decay susceptibility ranked below: Weidi＞Konglongdan＞Fengweimeigui＞Weiwang＞Fengweihuanghou＞Weihou. Final decay rates reached: Konglongdan (100% ), Weidi (53.3% ), Fengweimeigui (40%), Weiwang (23%), Fengweihuanghou (13.33%), and Weihou (0%). Low-temperature storage significantly enhanced both antioxidant enzyme activities and fruit quality. Correlation analysis revealed varying degrees of interindicator relationships with information overlap. Principal component analysis demonstrated Weihou exhibited optimal storage quality and tolerance, followed by Fengweihuanghou and Weidi, and then Weiwang and Konglongdan, with Fengweimeigui showing poorest performance. 【Conclusion】Physiological indices and storage related phenotypic changes of six plumcot varieties were measured during low temperature storage. The (4±1) ℃ storage condition effectively reduced fruit decay, slowed softening rate, balanced internal moisture content, and activated reactive oxygen species scavenging systems, thereby extending storage duration and improving fruit quality. Results demonstrated that Weihou exhibited superior storage quality under (4±1) ℃ conditions compared to the other five cultivars, ranking as the most storage tolerant variety, followed by Fengweihuanghou and Weidi, and then Weiwang and Konglongdan, with Fengweimeigui showing the poorest performance. These find-ings provide theoretical support for postharvest quality maintenance and storage period extension in plumcot fruits. Results indicated that storage at (4±1)℃ effectively preserved the quality of plumcot fruits. Among the tested cultivars, Weihou exhibited the optimal storage performance due to its superior comprehensive characteristics and more efficient antioxidant system, outperforming the other five varieties. The storage quality ranking was as follows: Weihou＞Fengweihuanghou＞Weidi＞Weiwang＞ Konglongdan＞Fengweimeigui. These findings provide critical scientific basis for cultivar selection and postharvest management in the plumcot industry, with significant practical implications for extending shelf life and enhancing commercial value.