Exogenous calcium fertilizer supplementation regulates production period in djulis (Chenopodium formosanum Koidz.)

ABSTRACT In this study, red and yellow varieties of djulis (Chenopodium formosanum Koidz) were cultivated in spring and autumn, and the effects of calcium carbonate treatment on their growth traits, antioxidant capacity, and grain maturation were examined. This study showed that calcium carbonate treatment increased the plant height and stem thickness in the red variety of djulis. The treatment also significantly increases the yield components of the red variety of djulis, such as spike length and thousand-grain weight. Treating the red variety of djulis with calcium carbonate in spring significantly increased the antioxidant enzyme activity such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) activities. Interestingly, results indicated that calcium carbonate treatment could promote the early maturation of the mid-late-maturing red variety of djulis and delay the maturation of the early-maturing yellow variety. Hence this experiment concludes that the exogenous calcium treatment in djulis can regulate grain maturation and promote growth, yield, and antioxidant enzyme activity; however, the growing season and the varietal effects play a vital role in determining the overall productivity of the djulis crop. Graphical abstract