Effect of Calcium on the Growth of Djulis (Chenopodium formosanum Koidz.) Sprouts

Taiwanese quinoa (Chenopodium formosanum Koidz, commonly known as djulis) is a close relative of quinoa, is rich in nutritional value and high active components, such as, betaine and polyphenols, and is a vital food crop. We investigated the effects of calcium carbonate on the growth and physiology of Djulis sprouts because calcium is an essential nutrient for plants that can strengthen a plant’s root system and improve its nutrient absorption; moreover, under abiotic stress, calcium transmits messages to enhance cell tolerance. Experiments were conducted using 0, 1.25, 2.5, and 5 mM calcium carbonate hydroponic liquid treatment. Treatment with 5 mM calcium carbonate promoted the growth of djulis; specifically, root length, plant height, aboveground fresh weight, and dry weight increased by 55%, 12%, 37%, and 17%, respectively. In further investigation of the physiological change of djulis sprouts treated with calcium carbonate, the results showed that after 5 days of treatment with 5 mM calcium carbonate, the contents of hydrogen peroxide and malondialdehyde decreased significantly while the chlorophyll content increased significantly. Antioxidant enzyme activity was significantly improved. The activities of superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase were increased by 42%, 25%, 35.7%, and 56.4%, respectively, and the calcium content of the aboveground and underground plant parts was increased fourfold and threefold, respectively. The content of proline, regarded as an osmoprotectant, was reduced by 12%. Thus, we concluded that treatment of djulis sprouts with 5 mM calcium carbonate can improve their antioxidant capacity, reduce the content of reactive oxygen species, and promote crop growth.