Abstract

Experiment was conducted in a pot to determine the effect of fruiting on antinutrients (soluble and total oxalates), toxic substances (cyanide and nitrate) and some micronutrients (vitamin C, and β-carotene, a provitamin A) and mineral elements (Fe, Mg, Zn, Cu, Ca, Na and K) in Corchorus olitorius grown on nitrogen and non-nitrogen treated soil. The vegetable leaves were harvested at market maturity (vegetative phase) and fruiting (reproductive phase) and was subjected to chemical analysis. The results showed that fruiting significantly increased the β-carotene, cyanide, soluble and total oxalate concentrations in the control and nitrogen treated vegetable, except that the significant increase in β-carotene was observed only in control. Nitrate and vitamin C concentrations in the vegetable were however, reduced with fruiting irrespective of soil nitrogen levels. Similarly, fruiting significantly decreases the Fe, Mg and Cu concentrations in the control while significant decrease in K concentration was observed in nitrogen fertilized vegetable. The concentrations of Zn and Na in the vegetable were not affected by fruiting; however, the Ca concentration was significantly elevated in nitrogen treated vegetable. The results conclude that the concentrations of most plant toxins and nutrients were significantly elevated and reduced respectively, with fruiting of C. olitorius.

Key words: Corchorus olitorius, micronutrients, antinutrients, toxic substances, market maturity, fruiting, soil nitrogen levels.