The Effects of Foliar Potassium (K) and Zinc (Zn) Applications on Plant Growth and Soil Enzyme Activities in Second-crop Sunflower (Helianthus annuus L.)

Authors : Suat Cun, Hakan Yıldırım, Zemzem Fırat

Pages : 365-379

Doi:10.24180/ijaws.1725264

View : 73 | Download : 221

Publication Date : 2025-12-29

Article Type : Research Paper

Abstract :This study was conducted in 2024 under the ecological conditions of Şanlıurfa Province to investigate the effects of potassium (K), zinc (Zn), and their combined foliar application (K+Zn) on plant growth, yield, and soil enzyme activities. The experiment was established using the Suomi sunflower (Helianthus annuus L.) cultivar, following a randomized complete block design with three replications. Foliar treatments were applied twice: at the 6–8 leaf stage and before flowering. The treatments consisted of a control (distilled water only), K (0.25% K₂SO₄), Zn (0.25% ZnSO₄·7H₂O), and K+Zn (0.25% K₂SO₄ + 0.25% ZnSO₄·7H₂O), all sprayed at a rate of 20 L da⁻¹. According to the results, the K, Zn, and K+Zn applications had statistically significant effects on fresh and dry plant weight (g), flower head diameter (cm), number of seeds per head, seed yield (count), 1000-seeds weight (g), seed length (mm), kernel ratio (%), and seed yield per decare (kg da⁻¹), as well as on catalase (CAT) activity, a key biochemical indicator of soil health. The individual application of K and Zn positively affected both plant and soil parameters, while their combined application (K+Zn) yielded the most pronounced positive results. Foliar application of K, Zn, and particularly K+Zn significantly influenced sunflower growth and also had notable effects on soil enzyme activity and overall soil health.
Keywords : Ayçiçeği, K ve Zn, Bitki besleme, Toprak enzimleri

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