Shade and Drought Stress-Induced Changes in Phenolic Content of Wild Oat (Avena fatua L.) Seeds

Plants develop under a wide range of maternal environments, depending on the time of emergence, prevailing competition from other plants, and presence or absence of other biotic or abiotic stress factors. Stress factors, such as light limitation and drought, during plant development typically reduces the reproductive allocation to seeds, resulting in fewer and often smaller seeds. Such stress factors may also influence seed quality traits associated with persistence in the soil, such as seed dormancy and chemical defense. For this research, we hypothesized that light limitation and drought during wild oat (Avena fatua L.) seed development would result in reduced allocation to seed phenolics and other aliphatic organic acids previously identified in the seeds of this species. Wild oat isolines (M73 and SH430) were grown in the greenhouse under cyclic drought conditions (2005 only) or two levels of shade (50 and 70%; 2005 and 2006) achieved with standard black shade cloth. The soluble and cellular bound chemical constituents were identified and quantified using gas chromatography - mass spectrometry. The shade and drought stress treatments often significantly affected the mass of the caryopsis and hull seed fractions, as well as the phenolic content of these seed fractions, depending upon isoline, seed fraction, phenolic fraction, and specific phenolics analyzed. Phenolic content of the hull was reduced by the stress environments by up to 48%, whereas there was some evidence of an increase in the soluble phenolic content of the caryopsis in response to the stress environments. Ferulic and p-coumaric acids were the most abundant phenolic acids in both soluble and bound fractions, and bound phenolics comprised generally 95% or more of total phenolics. There was no discernable evidence that the aliphatic organic content was affected by the stress environments. Our results indicate that plant stress during seed development can reduce both the physical and chemical defense in seeds, which may result in seeds that are less persistent in the soil seed bank and potentially less of a weed management concern

Organic wheat: Profitable niche market for conventional wheat producers?

Few cropping alternatives exist for growers in the semi-arid dryland wheat producing area in the Palouse region of the Pacific Northwest. This lack of alternatives makes producers vulnerable both from an economic and an agronomic standpoint. Characterized by its hilly landscape and deep loess soils, the Palouse is known for its record high wheat yields as well as its historically high levels of soil erosion. Wheat is the dominant crop here, with few profitable alternatives. In this study we explore the potential for increasing economic and environmental sustainability in this region by incorporating organic reduced tillage (ORT) cropping systems into conventional farming operations using results from six years of organic cropping system trials conducted near Washington State University’s Pullman campus. Could organic wheat production provide access to a more profitable market than the conventional commodity market? While organic wheat prices fluctuated from 2010 to 2014, they were consistently higher than conventional prices. Yields in organic systems may be more variable than in conventional systems due to insufficient nitrogen input, weed competition, diseases and pests, and more restricted tools to address these obstacles. Lower input costs in organic management can increase profitability, though this is not always the case. This variability highlights the need to analyze the factors that determine profitability within any given alternative cropping system to assess risk and feasibility on a regional basis. We have developed a spreadsheet tool that allows growers to adjust assumptions on yields, input costs, and crop prices and compare profitability for different cropping systems over time

Implications of Environmental Stress during Seed Development on Reproductive and Seed Bank Persistence Traits in Wild Oat (Avena fatua L.)

agronom