Germination and Seedling Growth of Zea mays L., Sorghum bicolor L. and Pennisetum americanum L. Under Varying Concentrations of Bilge Water

Abstract

Corn (Zea mays L.) [SUWAN =1-SR 063802 (yellow maize) and T.Z.R. (white maize)], guinea corn (Sorghum bicolor L.) and millet (Pennisetum americanum L.) tolerance to bilge water of varying concentrations [25, 50, 75, 100% (v/v)] was assessed at germination and seedling growth stages. Results obtained from physicochemical analysis of the bilge water revealed that it was slightly acidic (pH 5.91) and the concentration of Zn, Ni and Pb in the wastewater were higher than the National Environmental Standards and Regulation Enforcement Agency (NESREA) and United States Environmental Protection Agency (USEPA) limits for effluent discharge. The wastewate was found to inhibit the germination of all the seed types used and were concentration-dependent, for instance, treatment of S. bicolor seeds with 25% bilge water produced only 52% germination at 96 h while 28% germination was recorded for seeds treated with the stock at the same time interval. Length of radicle and plumule of the seedlings decreased with increase in bilge water concentration. The longest roots (44.6±0.44 - 19.6±0.40 cm) were produced in the control for all the seed types while the shortest roots (11.3±0.36 cm) were produced in the seedlings of S. bicolor grown on the undiluted bilge water. All the seedlings cultivated in the wastewater developed toxicity symptoms but more chlorotic and necrotic regions were observed at higher concentrations. S. bicolor was least tolerant while P. americanum was the most tolerant to the wastewater. Germination inhibition is attributed primarily to the acidity, trace and heavy metals contents of the bilge water. The results show that cereals were suitable for evaluating the effects of the wastewater in plant growth bioassays.