FOLIAR APPLIED POTASSIUM: EFFECTS ON CANTALOUPE QUALITY
Cantaloupe [Cucumis melo L. (Reticulatus Group)] fruit quality (ascorbic acid, beta-carotene, total free sugars, and soluble solids concentration (SSC)) is directly related to plant potassium (K) concentration during fruit growth and maturation. During fruiting, soil fertilization alone is often inadequate due to poor root uptake and competitive uptake inhibition from calcium and magnesium. Foliar applications of glycine-complexed K during cantaloupe fruit development has been shown to improve fruit quality, however, the influence of organic-complexed K vs. an inorganic salt form has not been determined. In this study, the effects of two K sources; glycine-complexed K vs. KCl (with or without a surfactant) were studied following application of K during fruit growth and maturation of glasshouse grown orange-flesh cantaloupe Cruiser. Plants were fertilized throughout the study with soil-applied N-P-K fertilizer. Flowers were hand pollinated and only one fruit per plant was allowed to develop. Starting at 3 to 5 d after fruit set, and up to 3 to 5 d prior to fruit maturity (i.e. full slip), entire plants were sprayed weekly, including the fruit, with a glycine-complexed potassium (Potassium Metalosate, 24% K diluted to 4.0 mLL-1) or KCl, (24% K diluted to 4.0 mLL-1) with or without a surfactant. Fruit from plants receiving supplemental foliar K were firmer, both externally and internally, than those from non-treated control plants. Increased fruit tissue firmness was accompanied by higher cell pressure potentials of K treated plants vs. control. In general, all K treated fruit had significantly higher SSC, total sugars, total ascorbic acid, and beta-carotene concentrations than control fruit. Autumn grown fruit, generally had higher SSC, total sugars, total ascorbic acid and beta-carotene concentrations than spring-grown fruits regardless of K treatment. There were no consistent differences among the K sources (with or without surfactant) on these fruit quality parameters, however, addition of a surfactant tended to increase SSC and beta-carotene in some instances.
E. Lester, G. and L. Jifon, J. (2007). FOLIAR APPLIED POTASSIUM: EFFECTS ON CANTALOUPE QUALITY. Acta Hortic. 731, 115-120
Cucumis melo L. (Reticulatus group), ascorbic acid, beta-carotene, color, KCl, maturity, firmness, sugars, soluble solids