Impact of the growth stages and seasons of harvesting cassava (Manihot esculenta Crantz) leaves on heavy trace elements and antioxidant activity

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 plannting (MAP) and seasons. Heavy metals were assessed by Microwave Plasma Atomic Emission Spectroscopy. Results showed significant (p<0.05) effect of harvesting month and season on HMs. However Pb and Co did not detected at 6 MAP and 9 MAP. Cd was also not detected 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 antioxidants compounds at different growths and seasons.