Foliar potassium fertilization improves fruit quality of field‐grown muskmelon on calcareous soils in south Texas

BACKGROUND: Among plant nutrients, potassium (K) has the strongest influence on crop quality parameters that determine consumer preference. However, soil and plant factors often limit adequate soil K uptake to satisfy quality requirements during fruit development stages. The objectives of this multiyear field study with muskmelon were to determine if this apparent K deficiency and the associated fruit quality limitations can be alleviated by supplementing soil‐derived K with foliar K nutrition, and whether differences exist among potential foliar K salts. RESULTS: Foliar K treatments increased tissue K concentrations, fruit sugars and bioactive compounds (ascorbic acid and β‐carotene) by 19%, 21% and 15%, respectively, even though soil K levels were high, indicating that soil K alone was inadequate to improve these quality traits. All the K salts evaluated increased tissue K and fruit quality traits; however, no clear trends in the relative magnitudes of these enhancements were apparent among K sources, except for KNO3 which consistently resulted in non‐significant effects. CONCLUSIONS: These results demonstrate that late‐season foliar K feeding can improve fruit quality of muskmelons grown on calcareous soils. The data also reveal differences among K salts and suggest a reassessment of K management strategies aimed at improving quality.