Effects of Potassium Applications on Growth, Tuber Yield, and Quality Parameters of Kohlrabi (Brassica oleracea var. gongylodes)

Abstract

Potassium plays an important role in plant growth, assimilate transport, yield formation, and quality development in vegetable crops. Therefore, determining an appropriate potassium fertilization rate is important for improving the productivity and quality of kohlrabi. This study evaluated the effects of different potassium rates on the growth, yield, and quality characteristics of the Korist F1 kohlrabi cultivar grown under unheated greenhouse conditions during the autumn–winter growing season in Korkuteli, Antalya, Türkiye. The experiment was established according to randomized complete block design with four potassium levels (Control, 100, 200, and 300kgha-1 K₂O) and four replications. Plant fresh weight, leaf number, and leaf fresh weight in kohlrabi increased substantially with potassium application compared to the control. The treatments of 200 and 300kgha-1 K₂O produced the largest total plant fresh yields, totaling 57.60 and 61.42tha-1, respectively. The greatest increase in tuber fresh yield was obtained with the 300kgha-1 K₂O treatment, with a value of 31.91tha-1, followed by the 200kgha-1 K₂O treatment, which resulted in a tuber fresh yield of 28.52tha-1. The 200kgha-1 K₂O treatment demonstrated a beneficial impact on quality indicators, yielding the highest values for electrical conductivity (EC) and soluble solids content. Potassium fertilization significantly enhanced growth, production, and quality characteristics in kohlrabi, with 200–300kgha-1 K₂O being optimal for yield, whereas 200kgha-1 K₂O was more advantageous for quality attributes.