Effect of Heavy Metal Stress on Seed Germination and Relative Water Content in Tomato Genotypes

Heavy metal contamination is a serious problem because it harms soil health, reduces crop yield, and affects food safety. Among these metals, lead (Pb) is especially harmful due to its high toxicity, long persistence in the environment, and tendency to accumulate in food crops like tomato. Six tomato genotypes were treated with four levels of lead heavy metal stress (50, 100, 200, and 300 ppm of lead nitrate) along with normal water as control. The results clearly showed that lead stress caused changes in physiological parameters, especially germination percentage and relative water content (RWC). Germination percentage decreased with the increase in lead concentration. The lowest germination percentage (29.3 %) was recorded in JTL-2105 at 300 ppm, while the highest mean germination percentage (68.7%) was maintained by GT-1. Similarly, RWC also declined as the stress level increased. The lowest RWC (69.24%) was observed in JTL-2105 at 300 ppm, whereas the highest RWC (87.33%) was found in GT-1 across all stress levels. These results suggest that GT-1 is more tolerant to lead stress, while JTL-2105 is the most sensitive genotype.Tolerant genotypes like GT-1 could be used to breed stronger tomato varieties.