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Kathryn S. Orvis and Irwin L. Goldman

Heart attack and stroke, a leading cause of death in the United States, have been associated with blood platelet aggregation. Onion extract inhibits blood platelet aggregation both in vitro and in vivo. Current trends toward natural foods and health remedies may point to the importance of onion-induced antiplatelet activity (OIAA). The genetic control of OIAA has yet to be revealed. One-hundred-eighty-three F3 families were derived from a long-day mild inbred line crossed to a long-day pungent inbred line that differ by for OIAA by 67%. Families were grown in a RCB design with two replications in muck soil (Randolph, Wis.) in 1997. Extracts were made from crushing bulb tissue in a mechanical juicer. F3 families were evaluated for OIAA and soluble solids (SS). OIAA was measured by electrical impedance aggregometry using two human blood donors. Endpoint (ohms) and slope of the aggregation curve were recorded. SS were measured by refractometry. F3 families were significantly different for OIAA and SS (P < 0.0001) in the ANOVA. A strong positive correlation of 0.96 was revealed for slope of curve and endpoint across families, replications, and blood donors. This correlation has not been previously reported for onion and suggests that for these families, descriptions of OIAA based on either rate of aggregation or endpoint are functionally equivalent. Both SS and OIAA exhibit transgressive segregation in this group of F3 families. Twenty percent exhibit OIAA stronger than the pungent parent and 5% were less than the mild parent. The family with the highest OIAA was 4-fold higher than the pungent parent of the cross, which could be useful in future onion breeding efforts. In addition, transgressive segregation in these families aids in QTL investigations for OIAA, SS and other economically important traits.

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Kathryn S. Orvis and Irwin L. Goldman

Organosulfur compounds in onion extracts inhibit the aggregation of human blood platelets. Antiplatelet activity is important to human cardiovascular health. We hypothesized that modification of sulfur fertility may increase organosulfur compound concentration and thereby affect platelet inhibitory activity in onion. Four contrasting onion genotypes were grown at four sulfur levels in a hydroponic system in the greenhouse and in contrasting sulfur environments in seven field locations in Wisconsin, Oregon, and New York. The contrasting field sites were comprised of sandy soils with a mean sulfate level of 5.4 ppm and muck soils with a mean sulfate level of 20.3 ppm. Onions grown in field environments with increased soil sulfur concentrations had significantly higher antiplatelet activity (33% higher than sand-grown onions; P < 0.001). The greenhouse experiment was conducted in hydroponics with nutrient solutions containing four sulfur levels ranging from 0.8 mM to 15 mM sulfate. The 10-mM sulfur treatment resulted in onion bulbs with 10% higher antiplatelet activity over those grown in the 0.8-mM sulfur treatment (P < 0.06). These data suggest that sulfur concentration in nutrient solution and in soil may be directly responsible for the increased antiplatelet activity in onion extracts observed in this study.

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Matthew J. Kararo, Kathryn S. Orvis and Neil A. Knobloch

Eat Your Way to Better Health (EYWTBH) is a garden-based nutrition education program that was conducted and evaluated for 3 years in Indiana third-grade classrooms. Program participants started and maintained their own school gardens as a part of an authentic experiential learning curriculum designed to reconnect youth with where their food comes from and educate about healthy eating habits. Implementation lasted between 8 and 12 weeks and outcomes were evaluated using pre- and postprogram questionnaires. Results showed that upon completion of the EYWTBH program, youth reported a higher healthy food choice self-efficacy, as well as a higher variety of fruit and vegetable consumption. Relationships among the variables were identified and discussed in the context of improving future school garden nutrition programs.

Open access

Elizabeth A. Gall, B. Rosie Lerner and Kathryn S. Orvis

In the United States, more than 80 million households participate in some type of gardening activity, including lawn care, vegetable gardening, and flower gardening. This considerable interest in gardening has led to the demand for accurate information about horticultural topics, trends, and research. One credible source for this information is the Extension Master Gardener (MG) Program, of which volunteering is a foundational component. Descriptive characteristics of Purdue Master Gardener (PMG) and PMG interns, characteristics of program participation, and volunteer behaviors were measured through an online survey questionnaire. Demographics, attitudes, self-efficacy, participation in the PMG program, and prior volunteering experience were measured and relationships between predictive variables and total volunteer hours were explored. Overall, the data revealed participants (N = 673) had strong positive attitudes about volunteering. Participants also reported having increased self-efficacy through participation in the MG program, and attitudes and self-efficacy were highly correlated. Based on the results and theoretical framework, a model was developed that can be used to predict volunteering behaviors within MG programs. The predictive model for volunteering behavior revealed that the number of years as an MG and the participant’s level of self-efficacy were good predictors of the total number of volunteer hours.