Germination and Survival of Maize and Beans Seeds: Effects of Irrigation with NaCl and Heavy Metals Contaminated Water

Abstract

Metal toxicity and soil salinity at excessive levels in soils are toxic to plants. The main objective of this study was to demonstrate the effects of water salinity (NaCl) and heavy metal concentration on germination and seedling characteristics of maize and beans seeds. Different concentrations of NaCl (0 to 35000 mg/L) and Zn2+, Cu2+ and Pb2+ with concentrations 0 to 600 μmol/L each were used separately. These solutions were used to irrigate maize and bean seeds for 30 days. Data was taken daily for the following parameters; “the number of germinated seeds, shoot length, shoot circumference, leaf area index, leaf colors, senescence, and disease occurrences.” The crops were uprooted at the end of the 30 days and their wet masses were measured and recorded. Results indicated that seed germination reduced with an increase in the concentration of NaCl for both maize and beans with 0% germination recorded in concentrations > 5000 mg/L. The same trends were observed for other parameters, the shoot length, the leaf area index, and the shoot circumference. “For heavy metals, the trends were similar. Beans growth was more affected by Zn and Cu but maize growth was more affected by Pb.” The dry masses and wet masses of the crops with higher concentrations of metals and salts were very low compared to the control experiments. For the effects of salinity and heavy metals on beans and maize seeds, there was a significant difference (P ≤ 0.001) between all tested concentrations and the control for all growth parameters monitored. It was concluded from the results that salinity and heavy metals affect the germination and seedling characteristics of maize and beans; though some metals are essential, their presence in higher concentrations instead cause harm.