Dynamic Analysis of Calcium and Oxalic Acid Content in Different Varieties of Chenopodium quinoa Leaves During Growth Period

In order to find out the content of calcium and oxalic acid in the leaves of the genus Chenopodium, the main cultivated plant in Zhejiang Province, Ch. Quinoa ‘Longli 1’ Ch. Quinoa ‘Qingli 4’ Ch. Quinoa ‘Jili 2’ and Chenopodium formosanum were used as research objects and determined the content of calcium and oxalic acid in different forms within the edible period. The results showed that during the edible period of quinoa leaves, the bound calcium was mainly calcium, accounting for an average of more than 92% of the total calcium. Among them, Ch. Quinoa ‘Longli 1’ accounted for the most, reaching 97.3%, while the highest content was in Chenopodium formosanum, reaching 2.16 g·kg⁻¹. The combined calcium content shows a continuous increasing trend, with the highest increase being in Ch. Quinoa ‘Jili 2’, which increased from 0.958 g·kg⁻¹to 1.887g·kg⁻¹. Ca²⁺ also showed continuous increasing trend, with a large increase in the early stage and a large increase in the later stage. The largest increment was Chenopodium formosanum, from 0.026 g·kg⁻¹ to 0.349 g·kg⁻¹. The average content of Ca²⁺ was still highest in Chenopodium formosanum, reaching 0.182 g·kg⁻¹. Water soluble oxalic acid was the main form of oxalic acid present in quinoa leaves, with an average content of 5.78 g·kg⁻¹, accounting for 93.4% of the total oxalic acid. Water soluble oxalic acid decreased within growth time, with the largest decrease being in Ch. Quinoa ‘Longli 1’. The soluble oxalic acid content decreased by 2.352 g·kg⁻¹ between the beginning and end samples, and the largest decrease was Ch. Quinoa ‘Longli 1’, reaching 35%. The dynamic content of total oxalic acid was similar to water-soluble oxalic acid, and the content still showed a continuous decreasing trend during the growth period. Among them, the largest reduction and decline was Ch. Quinoa ‘Longli 1’. The average content of oxalic acid in solid form leaves is highest in Ch. Quinoa ‘Longli 1’, reaching 0.65 g·kg⁻¹, while the content of Chenopodium formosanum leaves was the lowest. Correlation analysis showed that there was a significant negative correlation between oxalic acid content and growth time, significant positive correlation between total calcium content and growth time, and significant negative correlation between oxalic acid content and total calcium content.