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item Lester, Gene

Submitted to: International Congress on Plant Nutrition Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/10/2003
Publication Date: 1/7/2004
Citation: Lester, G.E. 2004. Foliar applied potassium: effects on cantaloupe quality, sugar content and related compounds. International Congress on Plant Nutrition Proceedings. pp. 49-57.

Interpretive Summary: This controlled environment greenhouse study demonstrated that foliar applied K can increase cantaloupe fruit quality, by increasing simple carbohydrate content, ascorbic acid and beta-carotene levels. These studies will be repeated in both greenhouse as well as in field trials. It is expected that these foliar K applied trials, will be as encouraging, in demonstrating the dramatic benefit to muskmelon fruits (both cantaloupe and perhaps honeydew melons), and in improving K content and subsequently increasing soluble solids concentration, total sugars, ascorbic acid and beta-carotene contents. Thus, melon fruit quality and marketability are expected to benefit by following this relatively simple and inexpensive management tool.

Technical Abstract: Cantaloupe fruit sugar content is directly related to potassium (K)-mediated phloem loading and unloading of sucrose into the fruit. Improving K content in melons, during fruit growth and maturation through soil applied fertilization, is a problem as root uptake of K is poor at this stage of growth and K competes with the uptake of Ca and Mg, two essential minerals needed for melon fruit membrane structure, function and postharvest shelf-life. Netted, orange-flesh muskmelon [Cucumis melo L. (Reticulatus Group) 'Cruiser'] fruits were grown in the greenhouse during the spring of 2003 and received regular N-P-K soil fertilization throughout the study. Three to 5 days after anthesis (fruit set) and up to 3 to 5 days prior to abscission (full-slip), amino acid complexed potassium (Potassium Metalosate 24% K) at 4.0 mL.L-1 (0.51 was sprayed on the entire plant until run-off. Plants were sprayed either weekly, biweekly or not sprayed (control). Fruit from plants receiving weekly applications of foliar K matured two days earlier, and had significantly higher fruit K content, soluble solids concentration, total sugars, ascorbic acid (vitamin C), and beta-carotene content than fruit from plants not receiving foliar K applications.