Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 12, 2004
Publication Date: June 30, 2005
Citation: Lester, G.E. 2005. Whole plant applied potassium: Effect on cantaloupe fruit sugar content and related human wellness compounds. Acta Horticulturae. 682:487-492. Interpretive Summary: This controlled environment greenhouse study demonstrated that whole plant (foliar/fruit) 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/fruit K applied trials, will be as encouraging, in demonstrating the dramatic benefit to muskmelon fruits (both cantaloupe and perhaps honey dew melons) 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 oz.gal-1) was sprayed on the leaves and fruit until run-off. Plants were sprayed either weekly, biweekly or not sprayed (control). Fruit from plants receiving weekly applications of foliar/fruit 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.