Comprehensive analysis of the integrated quality of cultivated kelp (Saccharina japonica) in three major producing provinces of China

Saccharina japonica is a commercially important species in the seaweed industry, with a long history of cultivation. Understanding the differences in the integrated quality of S. japonica across major production regions is necessary for achieving high-quality output and maximizing resource utilization efficiency. However, to date, comprehensive analyses and evaluations of S. japonica have received limited attention. In this study, we analyzed variations and characteristics of 17 physical and chemical indices of S. japonica from nine cultivated populations across the three primary producing provinces in China, namely Fujian, Liaoning and Shandong. Correlation and path analysis were used to explore the interrelationships among the indices, while hierarchical cluster analysis was used to further identify similarities and differences among populations. We employed two comprehensive analysis methods: grey correlation degree analysis (GCDA) and dynamic technique for order preference by similarity to ideal solution (DTOPSIS) to evaluate the integrated quality of S. japonica . The results showed that coefficients of variation for all physical and chemical indices were 9.4 %–54.6 %, with the color index b * exhibiting the greatest variability. Significant correlations were observed among the physical and chemical indices, and blade length and width were identified as key determinants of fresh weight. Moreover, physical and chemical indices showed significant differences among populations and producing provinces. S. japonica from Liaoning exhibited superior morphological traits, while samples from Shandong displayed better appearance color and higher mannitol content. According to the ranking from the two comprehensive analysis methods, S. japonica from Liaoning had the best overall integrated quality. These findings provide a foundation for the scientific evaluation of the integrated quality of cultivated S. japonica , offering insights for breeding and cultivation strategies, and promoting the high-value utilization of S. japonica . • There is considerable variability and correlation among the physical and chemical traits of Saccharina japonica . • Significant difference of physical and chemical traits exist among populations and producing regions of S. japonica . • Comprehensive analysis method can assess the integrated quality of S. japonica based on its physical and chemical traits. • The integrated quality of S. japonica from Liaoning is superior to that from Fujian and Shandong provinces in China.