DISSECTING CONTRIBUTIONS OF QUINOA AND BUCKWHEAT TO AGROECOSYSTEM AND HUMAN HEALTH

Rachel Sarah Breslauer

doi:10.7273/000006492

No addition to a crop rotation is a silver bullet for addressing concerns about food security, nutrition, and cropping system resilience. New food crops can add functional diversity into an agroecosystem and food system but are rarely monoliths in their contributions. This dissertation attempts to advance our understanding of the value that quinoa (Chenopodium quinoa Willd.) and buckwheat (Fagopyrum esculentum Moench.) can bring as novel features of western Washington (WWA) crop rotations. Quinoa seed proteins have essential amino acid (EAA) profiles that are close to human requirements, but there are many examples of quinoa failing to meet the human requirements for individual EAA. In a controlled environment study, we found that low mid-season nitrogen supply can cause low levels of isoleucine, leucine, and valine in quinoa seed. This study underscored the importance of managing soil fertility to maintain high-quality quinoa seed protein. We then explored the sensitivity of quinoa EAA to planting date in a WWA field study. This study was the first evaluation of EAA of field-grown quinoa for which all samples met adult EAA requirements. Planting date primarily affected overall protein content but did not affect EAA composition. The small differences in EAA observed in this study were attributed to the effect of variety and year. Buckwheat is an edible seed crop that is a common choice as a weed-suppressive cover crop in organic systems. Historically it has rarely been grown to seed in WWA and there is consequently limited production guidance for prospective growers in this region. A review of buckwheat production potential in WWA identified flooding sensitivity and heat sensitivity at seed set as key emerging production challenges in the region. This review was adapted into a production guide to provide resources to beginning buckwheat producers in WWA. The final portion of this dissertation considers the potential for breeding buckwheat and other edible seed crops (ESC) for providing multiple ecosystem services in WWA cropping systems. A baseline study of multifunctional performance of commercial buckwheat varieties in WWA found few differences in yield. However there were distinct differences in the onset of flowering and maturity as well as preliminary evidence that weed suppressive ability is variety-dependent. A survey of ESC producers in WWA found that across production scales, these producers grew ESC both as cash crops and to support soils in their systems. This study revealed that ESC producers use these crops to support nutrient cycling, soil formation, and fixing carbon into organic matter. Together, these studies highlight opportunities to improve management strategies and breeding targets for quinoa and buckwheat as novel crops in WWA.

DISSECTING CONTRIBUTIONS OF QUINOA AND BUCKWHEAT TO AGROECOSYSTEM AND HUMAN HEALTH

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