The Effects of Potassium on Plant Nutrient Concentration, Plant Development, and Rhizoctonia Rot (Rhizoctonia solani) in Pepper

Potassium has been identified as a vital nutrient for plant growth and functions. Studies have demonstrated its capacity to mitigate the severity of diseases by accelerating seed maturation and promoting robust root system development. In this study, we aimed to determine how increasing potassium doses affect the nutrient content, dry weight, root weight, and resistance to Rhizoctonia rot of the pepper plant. Pepper seedlings were used as plant material, and potassium sulfate was employed as the potassium fertilizer in this study. The experiment involved applying four different potassium doses (0, 50, 100, and 150 kg ha−1) to pepper seedlings, along with RS0 (control) and RS1 (diseased plant) in four replicates. At the end of the study, analyses of the plants’ nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), and boron (B) content, dry weights, and root weights were performed, in addition to disease assessments. An increase in N, P, K, Fe, and B content was observed with applied potassium doses, while a decrease in Mg content was noted. No significant change was detected in Cu content in pepper leaves, and the change in Mn content was not found to be statistically significant. An increase in plant dry weights was determined based on the applied treatments. The results indicated that plants subjected to potassium exhibited resistance to disease, an increase in root weights, and overall better conditions compared to samples without potassium. The best results in the experiments were achieved with the application of 150 kg ha−1 K2SO4. It was observed that certain rates of potassium had positive effects on disease factors by suppressing Rhizoctonia rot and can be used for biological control.