Effects of Different Potassium Foliar Fertilizers on Growth and Nutrition of Lettuce
Project no. 23944 · Status: Kapanmış · 2022
Summary
<p>In this study, the effects of different potassium (K) sources applied as foliar fertilizers on lettuce growth, quality (plant root and shoot weight, plant root and shoot length, total and discarded leaf count, stem diameter, leaf area index), yield (total and marketable), and nutrient content (N, P, K, Ca, Mg, Na; Fe, Cu, Zn, Mn) were investigated. The experiments were conducted over 18 months (including a year repeat) in a farmer’s field located in Ödemiş, İzmir, under Mediterranean climate conditions, following a randomized block design with five replications.</p><p>The experimental material was Iceberg lettuce, and the treatments included a control group with no foliar application, along with three K sources: potassium nitrate (KNO₃, 46% K₂O; 300 g/100L/da), potassium thiosulfate (25% K₂O; 550 ml/100L/da), and potassium phosphite (25% K₂O; 550 ml/100L/da). Application doses were adjusted based on the K₂O content of the fertilizers for comparability. Trials began in September in Ödemiş, İzmir, in both years, with the production periods lasting 54 days in the first year and 58 days in the second year. Fertilizer treatments were applied three times at the same doses, starting 15 days after transplanting and repeated at 15-day intervals.</p><p>The findings showed that potassium nitrate fertilizer significantly influenced growth parameters in both years. Regarding nutrient content, potassium nitrate had the greatest impact on N and K concentrations in both years. For phosphorus concentration, potassium phosphite was found to be the most effective treatment in both years.</p><p>Calcium concentration showed no significant differences among treatments in the first year, while potassium phosphite was the most effective in the second year. Similarly, potassium phosphite had the highest effect on magnesium concentration in both years. Sodium concentration was unaffected by the treatments in either year. Among micronutrients, iron concentration was not significantly influenced in the first year but was highest with potassium thiosulfate in the second year. Zinc concentration showed no statistical differences in the first year but was most significantly affected by potassium nitrate and potassium phosphite in the second year. Copper concentration reached its highest levels with potassium nitrate in both years, while manganese concentration remained statistically unaffected by the treatments.</p>