ABSTRACT

Plant secondary metabolites are mainly produced to protect plants from environmental stress and these metabolites are produced in small quantities. An attempt was made to increase host defence in cocoyam using turmeric extract sprayed at high concentrations to induce stress and stimulate increased production of defensive secondary metabolites. Cocoyam planted in pots in green house were sprayed for 3days with lOml/day of 1% and 5% turmeric acetone extract dissolved in 20% methanol containing 2 drops of tween-20 per 10ml. 3days after spraying, the phytochemical content ofthe cocoyam leaves before and after spraying were determined. Tween-20 and methanol sprays were used on the control cocoyam groups respectively under the same experimental conditions. The results of activities of 1% and 5% turmeric extract on phytochemical contents revealed significant (P< 0.05) raise when compared with the controls. One percent concentration gave a raise of4% (anthocyanins), 3% (phenols) and 1% (tannins). While 5% concentration gave 8%(anthocyanins), 8%(tannins) and 4% (phenols). However, there were no significant (P> 0.05) differences in the raise caused by both 1% and 5% concentrations in the levels of alkaloids and flavonoids. These results showed turmeric given al high concentration to plants via foliar application can induce increased phytochemical levels in cocoyam. Preliminary phytochemical evaluation based on visual assessment showed more of the phytochemical to be present in the acetone extract giving tannins, alkaloids and saponins to be present in moderate concentration while phenols were in high concentration.