Effects of Environment on Plant Secondary Compounds
Plants naturally produce primary and secondary compounds. Primary compounds are used for growth and development, and until recently secondary compounds (SCs) were thought of as metabolic waste products rendering foods and forages unpalatable for humans and other animals. However, research of the past 40 years has revealed endless benefits of SCs to soil, plants, and animals including humans.
All plants contain SCs and many of these compounds are thought to set a limit on intake for herbivores especially when offered as monocultures. However, in small doses these compounds may offer health benefits for humans and other animals. For instance, resveratrol a polyphenolic compound present in grapes, wine, soya, and peanuts helps prevent heart disease and various types of cancer in humans. Condensed tannins reduce internal parasites in ruminants, and enhance the absorption of amino acids in the small intestine.
Herbivores eat more and perform better when offered a variety of plants that vary in concentrations of different nutrients and secondary compounds. When plants are grown in monocultures, especially those bred to be low in SC, large amounts of fertilizer, herbicides and pesticides are needed to maintain the stand. Plants often benefit from growing in mixtures and reduce the need for the inputs listed above.
We know very little about how various grazing practices, agricultural methods, and mixtures of plants may affect concentrations of SCs. The dynamics between herbivory, above and below the soil surface, and the environment is an integral part of nature's circle of life. However, the research and views of how grazing impacts the environment are incredibly diverse.
USU graduate student, Andrea Clemensen, is interested in some agronomic as well as environmental factors that may affect concentration of certain SCs. Andrea is investigating how different management practices (animal impact vs. chemical inputs and machine harvesting) affect soil quality, nutrient cycling, and SC concentration, in addition to investigating how plant diversity (monocultures vs. two-way mixtures) affects primary and SCs in plants, as well as soil characteristics. Her research involves plants such as endophyte-infected tall fescue, (Festuca arundinacea), alkaloid containing reed canarygrass (Phalaris arundinacea), saponin-rich alfalfa (Medicago sativa),and tannin containing sainfoin (Onobrychis viciifolia) and birdsfoot trefoil (Lotus corniculatus).
The field work is conducted at Utah State University’s Agriculture Research Field Station near Lewiston, Utah, and laboratory analyses are conducted at Utah State University. The project is overseen by Ron Ryel, Associate Professor in Wildland Resources, Jennifer Reeve, Assistant Professor in Plants, Soil and Climate, Paul Grossl, Associate Professor in Plant, Soil and Climate, Daniel Cook, ARS USDA Research Plant Physiologist, and Tom Monaco, ARS USDA Research Ecologist.