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David LaGrange of Starr Produce and ARS plant physiologist Gene Lester (right) examine market quality of commercially grown cantaloupe from plants sprayed with potassium during fruit growth. Click the image for more information about it.

Increasing Nutrients in Melons May Boost Growers' Income

By Alfredo Flores
August 9, 2005

Spraying potassium on melons as they grow in the field boosts the fruit's beta carotene and vitamin C levels, according to Agricultural Research Service (ARS) scientists studying this method as a way to make melons more nutritious.

The United States is one of the world's leading producers and consumers of melons. Total U.S. per capita consumption of melons has increased by more than 23 percent in the past 15 years, to almost 30 pounds per person in 2004.

Melons are among the fruits and vegetables known for their human health-promoting levels of vitamins and minerals. Now Gene Lester, a postharvest plant physiologist in the ARS Crop Quality and Fruit Insects Research Unit at Weslaco, Texas, wants to further improve the nutrient content of melons.

Working with the largest cantaloupe and honeydew growers in Texas and other collaborators, Lester has extensively studied spraying potassium on melons during fruit growth. The potassium formulation is relatively simple, inexpensive to use, safe, readily available and can be combined with sprays for insects or disease, according to Lester.

In greenhouse and field studies on popular commercial melon varieties, applying potassium during fruit development greatly increased the fruit's level of beta carotene, one of the most powerful dietary antioxidants. Foliar application of potassium also aided the plants' photosynthesis, ultimately increasing the fruit's sugar content. This, in turn, raised levels of vitamin C and produced a better-tasting and sweeter melon.

Lester has also worked with Mike Grusak, a plant physiologist at the USDA-ARS Children's Nutrition Research Center in Houston, Texas. They collaborated on a study of calcium applications for honeydews and cantaloupes on the vine as a supplement--or alternative--to postharvest treatments to improve disease resistance, preserve quality and increase shelf life. Potassium and calcium can be applied together to make a firmer, more nutritious melon that can tolerate longer storage.

Read more about the research in the August 2005 issue of Agricultural Research magazine.