How to Grow Salt-Sensitive Vegetable Crops Under Salinization of Water Bodies in Southern Ukraine: The Potential of Seaweed (Ecklonia maxima) Extracts to Mitigate Salt Stress in Lettuce

<p>Water salinization in southern Ukraine, intensified by mine discharges and the destruction of the Kakhovka Dam, has severely reduced access to irrigation water suitable for vegetable cultivation. Farmers in affected regions now face restricted crop choices, relying largely on salt-tolerant grains and unable to grow salt-sensitive vegetables. The growth of lettuce (<em>Lactuca sativa</em> L.), a salt-sensitive crop, in a pot experiment, declined sharply within three days of irrigation with salt water, reaching concentrations of 100–200 mM NaCl in the soil substrate (70 per cent sandy loam and 30 per cent quartz sand). Pre-treatment with 1 per cent Kelpak, a seaweed-based biostimulant, partly reduced the impact of salt stress. The shoot dry weight assessment after eleven days of cultivation revealed a biomass reduction of up to 16 and 35 per cent in the 100 and 200 mM NaCl treatments, respectively, compared to the control. By contrast, the application of 1 per cent Kelpak increased plant biomass by 15 per cent at 100 mM and 25 per cent at 200 mM. These results suggest that biostimulant-based strategies can provide effective support for cultivating salt-sensitive vegetables under saline irrigation.</p>