Abstract
Salinity and lead are two important abiotic stresses that limit crop growth and yield. In this study, we assayed the effect of these stresses on tolerant and sensitive maize genotypes. Four-week-old maize plants were treated with 250 mM sodium chloride (NaCl) and 250 µM lead (Pb). Our results show that NaCl or Pb treatment of the sensitive genotype caused a significant reduction in the root length, plant height, total fresh and dry weights, as well as chlorophyll, and carotenoid content. Salt stress led to a significant decrease in the relative water content, shoot and root length, fresh and dry weight as well as leaf area and K(+) content but increase Na(+) content. Both NaCl and Pb stresses increased the antioxidant enzyme activity, proline content, malondialdehyde, and hydrogen peroxide levels. Principal component analysis (PCA) accounted for 69.8% and 16.5% of the total variation among all the variables studied. PCA also suggested a positive correlation between hydrogen peroxide, malondialdehyde, peroxidase, catalase, ascorbate peroxidase levels, and Na(+) content and a negative correlation between K(+) content, chlorophyll content, relative water content, leaf area, root length, plant height, and total fresh, and dry weights. Together, these results suggest that the salt-tolerant maize genotype is more suitable for adapting to Pb stress compared to the salt-sensitive genotype.