Effects of salicylic acid applications on the growth and plant nutrient content of white cabbage (brassica oleracea var. capitata subvar. alba) seedlings grown under salt stress conditions

This study investigated the effects of salicylic acid applications on the growth and plant nutrient content of white cabbage (Brassica oleracea var. capitata subvar. Alba) seedlings grown under salt stress conditions. The study was conducted in 2024 in the climate chamber of the Department of Horticulture, Faculty of Agriculture, Ordu University. The material used in the study was the Samsa F1 hybrid variety, which is suitable for cultivation in the Black Sea region and is grown for wrapping and fresh consumption. White cabbage seeds were sown in 45-cell trays filled with peat (Klassmann, Germany). When the seedlings reached the first true leaf stage, salicylic acid was sprayed, and salt stress was applied 2-3 days later. Salt doses were applied in three applications at 1-day intervals to prevent acute effects. In the study, the following parameters were measured in randomly selected seedlings from each plot: seedling height, hypocotyl diameter, leaf area, leaf water content, number of leaves, leaf thickness, fresh and dry weight of seedlings, chlorophyll index (SPAD), and macro and micro nutrient content. In the study conducted within the scope of this thesis, it was determined that seedling height, leaf area, leaf number, hypocotyl diameter, leaf relative water content, seedling wet and dry weight parameters decreased while leaf thickness and chlorophyll index (SPAD) parameters increased as salt concentration increased. 1.0 mm SA application was the most effective dose in alleviating the negative effects of salt stress. It maintained or increased seedling height, leaf area, seedling wet weight, seedling dry weight and chlorophyll content, especially under moderate salt stress (75 mM). 1.5 mM SA, on the other hand, suppressed growth and negatively affected wet weight, dry weight and seedling height with high dose effect. Salt x SA interaction was effective on seedling wet weight and leaf thickness. In terms of macro and micronutrients, increasing salt concentration increased the accumulation of Na and decreased the accumulation of some elements such as (K) and (S). On the contrary, the accumulation of some nutrients such as (Ca), (P), (Mn), (Zn) and (Cu) increased in response to salt stress under certain conditions. Salt and SA interaction had a significant effect on (Ca), (Fe), (P), (Na), (Cu), (Mn) and (Zn) contents. In line with all these results, salt stress negatively affected the growth of white head cabbage seedlings, and SA applications reduced the negative effects of salt stress, supported the growth of seedlings and maintained the nutrient balance.