Effect of inorganic fertilizer application on the flavonoid, phenol and steroid content of the leaves of Ocimum gratissimum (L) and Gongronema latifolium (Benth)

The influence of inorganic fertilizer application on the flavonoid, phenol and steroid content of the leaves of Ocimum gratissimum and Gongronema latifolium was investigated. Cultivated O. gratissimum and G. latifolium were treated with NPK (15:15:15) inorganic fertilizer at 100 kg/ha, 200 kg/ha, 300 kg/ha, 400 kg/ha and 500 kg/ha treatment levels in plastic planting buckets derived using the furrow slice method two months after seedling emergence. No fertilizer treatment served as control. Only one fertilizer application was made. Leaves of the plants were harvested for analysis one month after treatment. Inorganic fertilizer treatment did not affect the presence of flavonoids, phenols and steroids in the leaves of the plants, since both treated and untreated plants contained these phytochemicals. However, inorganic fertilizer treatment, affected the concentration of flavonoids, phenols and steroids in the leaves of the plants. There was significant increase (p < 0.05) in the phenol and steroid content of the leaves of O. gratissimum and G. latifolium, but had no significant effect on the flavonoid content of the leaves of O. gratissimum, but significantly (p <0.05) increased the flavonoid content of the leaves of G. latifolium. 500 kg/ha produced the highest concentration of flavonoids and steroids in the leaves of the plants, while 500 kg/ha and 100 kg/ha treatment levels produced the highest amount of phenols in the leaves of O. gratissimum and G. latifolium respectively. The least amount of flavonoid was obtained by the control treatment in the leaves of both plants, while the least amount of steroid was in 100 kg/ha and 200 kg/ha treatment levels. However, the 300 kg/ha treatment level produced the least amount of phenol in the leaves of both plants. The results obtained were discussed in view of the importance of these phytochemicals in maintenance of good health.