Ameliorative effect of Salicylic Acid on the Growth of Lettuce (Lactuca sativa L.) Seedling under Cadmium Stress

Worldwide, Lettuce (Lactuca sativa L.) is regarded as the most widely farmed vegetable. In Iraq, sewage water is used to irrigate lettuce that leading to health risks for consumers, particularly due to heavy metal contaminants, such as cadmium. This study was conducted as a factorial experiment in Taq-Taq city, Erbil, Iraq during the winter season 2021 to investigate the effects of soaking lettuce seeds in cadmium (Cd) (0, 10, 20, or 30mM) and salicylic acid (SA) (0, 2, 4, 6, or 8mM) on the germination and some seedling growth properties of this plant. Results show that soaking the seeds in distilled water led to a decrease in the percent of seeds germination compared to that soaked in Cd solutions, while exist of SA at moderate concentrations increase the germination percent. Most of the seedling growth characteristics exhibited a considerable increase with soaking seeds in Cd solution. SA in high concentration reduced significantly seeds germination and most of the seedling shoot and root characteristics, except the root length, which grew significantly. Most of the responses of Cd and SA were non-significant regarding chlorophyll a, b, and total carotenoids. This study concluded that soaking lettuce seeds in Cd up to 30mM and SA up to 4mM act as a stimulate hermetic effects on germination and subsequence growth of lettuce seedling, these findings confirm the increase growth and yield of lettuce irrigated by wastewater (including Cd) in Iraq and Iraqi Kurdistan region in spite of the increased health risks.