Quality Response of Two Mini Chinese Cabbage Cultivars to Different Calcium Levels

This study investigated the effects of different calcium levels on the nutritional quality and stress resistance of mini Chinese cabbage, focusing on the 'QYH' calcium-sensitive cultivar and the 'HN' calcium-tolerant cultivar. Plants were treated with five calcium levels (0, 2, 4, 6, and 8 mmol/L) to analyze the incidence of tip-burn, tissue calcium content, mineral accumulation, amino acid composition, and phenolic and flavonoid compound contents. The results showed that appropriate calcium levels significantly reduced tip-burn incidence. Specifically, 'QYH' exhibited no tip-burn symptoms at 6 mmol/L calcium, while 'HN' was tip-burn free at 4 mmol/L. Appropriate calcium levels also significantly increased the contents of soluble sugars, proteins, and ascorbic acid while reducing nitrate levels in both cultivars. For example, the soluble sugar content in 'QYH' increased by 119.05% under the 6 mmol/L calcium treatment. Similarly, 'HN' showed significant increases in soluble sugars, proteins, and ascorbic acid at 4 mmol/L. Amino acid and phenolic compound levels peaked at 6 mmol/L calcium in 'QYH', with rutin content in 'QYH' increasing by 181.58%. In 'HN' these compounds peaked at 4 mmol/L. Additionally, high calcium levels did not antagonize key minerals but reduced manganese accumulation. These findings highlight calcium's critical role in enhancing the nutritional quality of mini Chinese cabbage and provide a scientific basis for optimizing calcium fertilizer application for both 'QYH' and 'HN' cultivars.