The effects of foliar application of potassium fertilizers on tomato plant under drought stress

The yield of tomato, which is one of the most produced vegetables in the world, decreases significantly due to different abiotic stresses and drought is one of the most important abiotic stresses. Drought stress affects plant growth, resulting in reduced yields. In this study, the response of the tomato plant under different drought stress to the foliar application of potassium sulfate, potassium nitrate and potassium chloride fertilizers on the tomato plant was investigated. The experiment was carried out in a randomized block design with 3 replications in the ecological conditions of Çığır village, İdil district of Şırnak province, in the growing season of 2020. In the experiment, Kamenta F1 industrial tomato variety and domestic tomato genotype Fereng were used as plant material. In the experiment, 3 different irrigation levels, 100% irrigation (control), 66% irrigation and 33% irrigation were applied. In the study, 1% of foliar potassium sulfate, potassium nitrate and potassium chloride were applied as fertilizer. Evaluation of the green parts, proportional water content of leaves, leaf temperature, amount of leaf chlorophyll, membrane damage in leaf cells, fresh and dry weight of green parts and fruit, macro and micro nutrient element analysis (K, Ca, Mg, N, Cu, Fe, Zn, Mn), total sugar content, total phenolic and flavonoid substance determination, total fruit number, total yield, average fruit weight, fruit diameter and length, fruit firmness, fruit wall thickness, water-soluble dry matter and pH analysis has been made. As a result of the research, drought stress significantly decreased the Ca and Mg element content in green parts and fruit in both Kamenta F1 variety and Fereng tomato genotype compared to control (100% irrigation). It was determined that the applied potash fertilizers were effective on green parts, chlorophyll amount, Fe and Zn content in fruit, Zn content in green parts, average fruit weight in tomato plants. K2SO4 fertilizer application showed better results in leaf temperature, fruit length, fruit flesh firmness, fruit wall thickness, BRİX and total yield compared to other fertilizer (KNO3 and KCI) applications. Compared to the control, the best results were obtained in total sugar content, total phenolic and flavonoid substance content in plants under 33% irrigation conditions. As a result, it has been seen that the foliar application of K2SO4, KNO3 and KCI fertilizers under drought stress will have a positive effect on fruit yield quality parameters.