Impact of growth stage and harvest season on heavy trace elements and antioxidant activity of cassava (Manihot esculenta Crantz) leaves

The study assessed effects of plant growth and seasons of harvesting cassava (M. esculenta) leaves (CL) on antioxidants and heavy metals (HMs). The CL of five varieties include TMS92/0326, TMS96/1414, IRAD4115, EN and AD were collected at different months after planting (MAP) and seasons. Results showed significant (p < 0.05) effects of harvesting month and season on HMs. However Pb and Co were not found at 6 MAP and 9 MAP. Cd was also not found in IRAD4115, EN and AD at 15 MAP. Besides, higher content of HMs was observed in dry than in rainy season. All these variations were visualized by principal component analysis (PC1 x PC2: 58.15%). Concerning the antioxidant, it was also varied significantly through seasons and within varieties. This study revealed that CL are moderate in HMs and rich in antioxidant compounds at different growth and season, however 6-9MAP are the safe hervest periods while TMS96/1414 and EN varieties are recommended for healthy consumption.