Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/25/2009
Publication Date: 12/2/2009
Citation: Jifon, J.L., Lester, G.E. 2009. Foliar potassium fertilization improves fruit quality of field-grown muskmelon on calcareous soils in south Texas. Journal of the Science of Food and Agriculture. 89:2452-2460. Interpretive Summary: The data in this study demonstrate that the low potassium (K) concentration in calcareous soils is highly responsible for the poor quality of muskmelon fruit grown on such soils and that supplementing soil-derived K with foliar K applications during fruit development and maturation alleviates this K deficiency and improves muskmelon fruit quality, including the concentration of human-health bioactive compounds. Potassium sources such as potassium chloride, potassium sulfate, glycine-amino acid complexed potassium (Metalosate TM), monopotassium phosphate, and potassium thiosulfate improve melon fruit quality. Potassium nitrate is detrimental and not recommended for foliar feeding during fruit development and maturation.
Technical Abstract: Among plant nutrients, potassium (K) has the strongest influence on crop quality parameters that determine consumer preference. However, many soil plant factors often limit adequate soil K uptake to satisfy plant requirements during fruit development stages. The objectives of this multiyear field study were to determine if this apparent K deficiency and the associated fruit quality problems can be alleviated by supplementing soil-derived K with foliar K nutrition and whether differences exist among K salts for foliar feeding. Foliar K treatments resulted in higher K concentrations in plant tissues, even though pre-plant soil K concentrations were high, indicating that plant K uptake from the soil solution was not sufficient to satisfy plant requirements. Fruits from treatments receiving foliar K had higher soluble solid concentrations, total sugars, and bioactive compounds (ascorbic acid and beta-carotene). Among the different K salts, KNO(3) consistently resulted in non-significant effects on fruit quality compared to control treatments. The results demonstrate that carefully-timed foliar K nutrition can improve muskmelon fruit quality by alleviating the apparent K deficiency during fruit development. The data also reveal differences among potential K salts and suggest a reassessment of K management strategies aimed at improving fruit quality.