Effect of lead (Pb) on seed germination of water spinach (Ipomoea aquatica Forsk)

In this research, the effect of lead (Pb) on seed germination rate (%) of water spinach (Ipomoea aquatica Forsk) have been investigated. The seeds were placed in 6 × 4 × 2 cm rockwool moistened with distilled water (control) and aqueous solutions of PbCl2 (0, 50, 100, 150 and 200 μM). Germination test was done by sowing fifteen water spinach seeds with six replicates for each concentration Pb level for 4 days. Several parameters have been observed in the seed germination test. Such stress conditions revealed that by increasing the concentration of lead, the germination rate (%), the tolerance index (TI), and the seedling vigor index (SVI) decreased significantly, suggesting their toxic effect on water spinach. The obtained data were analyzed using one-way ANOVA. The results showed that for lead-treated seeds were significantly different compared to the controls and showed a gradual decrease towards an increase in lead concentration (Pb) in shoot and root fresh weight, shoot and root length, SVI, and, TI. Germination percentage and seedling dry weight of lead-treated germinated seeds were not significantly different compared to the controls. Due to limitations of the data, the maximum lead concentration thresholds for water spinach cannot be accurately determined, but it can be inferred that they would be greater than 100 and less than 200, respectively.