International Journal of Plant & Soil Science

Potassium is known for enhancing crop productivity, due to its active involvement in maintaining cation-anion balance, osmoregulation, photosynthesis, cytoplasmic pH regulation, proteins and starch synthesis, enzyme activation in plant system. Despite the recognized importance of potassium in citrus production, region-specific dose optimization for Kinnow mandarin in Punjab’s semi-arid soils remains largely unexplored, remained the main reason for poor fruit quality and yield due to adoption of sub-optimal levels of potassium application in kinnow. The present study was conducted to optimize potassium fertilizer dose in Kinnow mandarin for better fruit quality and production in Semi-arid zone of Punjab, India. The experiment was conducted during the year 2022 to 2024 using randomized block design with three replications, consisted of seven treatments of K₂O fertilizer (0.0, 0.2, 0.4, 0.6, 0.8, 1.0 and 1.2 kg/plant) applied in the month of December-January besides the recommended doses of fertilizers. The pooled data of 3 years revealed that fruit weight, size, juice content, soluble solids content, carotenoids and sugars content were improved substantially with K fertilizer than the control. Fruit weight, length and diameter increased by 13.4, 21.6 and 24.1%, respectively in the plants applied with 0.6 kg K₂O plant^-1 over the control, whereas higher dose of K₂O application enhanced granulation that resulted in lower recovery of juice content. The plants applied with lower K levels produced fruits of smaller size, thin peel and poor consumers’ acceptability. Correlation studies indicated that fruit size, weight and peel thickness were directly related with leaf and soil K content. These findings provide the region-specific recommendation for optimal potassium fertilization in Kinnow mandarin, supporting improved fruit yield, quality, and farmer profitability in Punjab’s semi-arid region.