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Purple coneflower (Echinacea purpurea Moench [L.]) is widely used as a health supplement and is cultivated for its production of bioactive phytochemicals. However, there is a lack of information on how agronomic planting designs and environment affect the phytochemical content of different coneflower tissues. Experimental plots were established at two locations in Minnesota to evaluate the effect of environment and agronomic planting design on the phytochemical profile of purple coneflower, as well as the relative content of several provisionally identified compounds. Root, stem, leaf, flower, and seed tissues were harvested, and extracts were analysed using liquid chromatography-mass spectrometry. The growing environment affected the levels of several caffeic acid derivatives in leaf, stem, and root tissue, but agronomic design had little to no effect on phytochemical content. Although all tissue types contained phytochemicals of medicinal interest, no single tissue contained the highest amount of all compounds with known bioactive properties, indicating that the most beneficial purple coneflower supplements may be the combination of several tissue types. Additionally, the phytochemical content of purple coneflower seed, which is uncommon in Echinacea supplements, was chemically similar to root tissue. Seed tissue, after additional evaluations, may be a suitable alternative for root in supplement mixtures. [ABSTRACT FROM AUTHOR]

Perennial flax (Linum spp.) breeding objectives at the University of Minnesota (UMN) are to develop agronomic (oilseed, fiber) and horticultural (cut flower, garden perennial) varieties that are hardy in Minnesota (USDA Plant Hardiness Zones 3 and 4). The objective of this research was to determine the range of cold hardiness in UMN perennial flax breeding populations compared with wild accessions of L. austriacum, L. lewisii, and L. perenne. Fifty‐three genotypes from seven populations were low temperature acclimated, followed by controlled freezing using a programmable freezer. The observed lethal temperature for 50% plant kill (LT50) ranged from >0 °C (0% survival) to <−12 °C (100% survival), for the test temperatures of 0, −4, −8, −10, and −12 °C. Cold damage was measured after 4 wk of regrowth as the proportion of alive shoots and a root damage rating. Significant negative correlations were observed between LT50 and proportion of alive shoots (r = −.918) and root damage rating (r = −.935). Both L. austriacum and L. perenne had significantly less cold damage than L. lewisii and the breeding populations. This study establishes methods of screening perennial flax cold tolerance that are more cost effective, rapid, and repeatable compared to field evaluations. Core Ideas: Controlled freezing tests were useful to identify hardy perennial flax species and genotypes.Lethal temperatures for 50% plant kill (LT50) were as low as ‐12 °C (hardy in MN USDA Z3–4).Linum austriacum and L. perenne had significantly less cold damage than L. lewisii and hybrids. [ABSTRACT FROM AUTHOR]

Establishing native perennial plants on the agricultural landscape can improve ecosystem services and provide marketable products, such as seed for restoration plantings and biomass for renewable energy. Native perennials of economic and ecological interest should be examined in different planting configurations over time to determine their suitability for sustained production. Canada milk vetch (Astragalus canadensis L.), purple coneflower (Echinacea purpurea L.), and showy tick trefoil (Desmodium canadense L.) were established at two locations in Minnesota to evaluate seed and vegetative biomass yields. These forbs were established in six different agronomic designs: three strip designs (one‐row, three‐rows, and six‐rows) and three community designs (monoculture, low‐richness polyculture, and high‐richness polyculture). Seed yield averaged 2995, 950, and 1157 kg ha−1 for Canada milk vetch, purple coneflower, and showy tick trefoil in the first year and declined for all species over time. Biomass yields averaged 6743, 2725, and 2869 kg ha−1 in the first year for Canada milk vetch, purple coneflower, and showy tick trefoil, respectively. Canada milk vetch biomass yields declined by 98% over time, and showy tick trefoil biomass yields increased by 40%. Seed and biomass yields were the lowest in one‐row strip design and greatest in the community designs, with little difference between monocultures and polycultures. Results suggest that production is maximized in community designs and that purple coneflower and showy tick trefoil have the potential for multiyear yields. [ABSTRACT FROM AUTHOR]

Sustainable intensification of agricultural systems has been suggested as a way to increase food, fiber, energy, and feed to meet future demands. Field pennycress (Thlaspi arvense L.) is proposed as a means for temporal intensification of agriculture, increasing profitability through oilseed production while providing needed cover to address soil and water quality issues. Field research was conducted across four environments in Minnesota to (i) evaluate pennycress planting date and seeding rate on pennycress and soybean [Glycine max (L.) Merr.] seed production and (ii) determine the role of pennycress systems as a weed management tool. Pennycress seeding rate had a direct effect on pennycress yield at Rosemount but not at Waseca or Lamberton locations. The use of a companion cover crop along with pennycress further reduced pennycress seed yield at Rosemount, but not Waseca or Lamberton suggesting that water availability is a key driver in pennycress productivity. The effect of pennycress and cover crops on soybean yield was also dependent on location. At Rosemount, soybean yield was reduced when pennycress was planted ahead of soybeans both years of the study while there was no effect of pennycress on soybean yield at Waseca. Although soybean yield was reduced at Rosemount, the combined pennycress and soybean seed yield was greater. This research shows the potential for a double cropping system of pennycress-soybean to increase overall seed yield and reduce early-season weed pressure. [ABSTRACT FROM AUTHOR]

Abstract: The use of perennial biomass crops is expected to increase and will likely be part of a diversified approach to cropping system design that focuses on multiple economic, ecological, and environmental benefits. Field experiments were conducted from 2006 to 2011 at three locations in Minnesota to quantify biomass production across a diverse set of perennial herbaceous and woody crops. Herbaceous crops were harvested annually in the fall while the woody crops were harvested once following five years of growth. Willow produced more total biomass than all other woody and herbaceous biomass crops across all locations. However, miscanthus biomass yield was similar to ‘SX67’ willow at St. Paul and Waseca, but was dependent on the cultivar of miscanthus. Prairie cordgrass cultivars were among the highest and most consistent yielding herbaceous biomass crops across locations. Miscanthus cultivars produced the highest annual dry matter yield of 35 Mg ha−1 yr−1 biomass, but only during the final year of the study. Other herbaceous crops such as switchgrass performed well in certain locations and may offer flexibility in cropping choice. This unique information on comparative biomass yield across a diversity of perennial crops will inform the overall decision-making process in a way that reduces risk and optimizes productivity in specific environments. This study shows that several biomass crop species can be successfully grown as part of a diversified biomass cropping enterprise. [Copyright &y& Elsevier]

Perennial biomass from grasslands managed for conservation of soil and biodiversity can be harvested for bioenergy. Until now, the quantity and quality of harvestable biomass from conservation grasslands in Minnesota, USA, was not known, and the factors that affect bioenergy potential from these systems have not been identified. We measured biomass yield, theoretical ethanol conversion efficiency, and plant tissue nitrogen (N) as metrics of bioenergy potential from mixed-species conservation grasslands harvested with commercial-scale equipment. With three years of data, we used mixed-effects models to determine factors that influence bioenergy potential. Sixty conservation grassland plots, each about 8 ha in size, were distributed among three locations in Minnesota. Harvest treatments were applied annually in autumn as a completely randomized block design. Biomass yield ranged from 0.5 to 5.7 Mg ha−1. May precipitation increased biomass yield while precipitation in all other growing season months showed no affect. Averaged across all locations and years, theoretical ethanol conversion efficiency was 450 l Mg−1 and the concentration of plant N was 7.1 g kg−1, both similar to dedicated herbaceous bioenergy crops such as switchgrass. Biomass yield did not decline in the second or third year of harvest. Across years, biomass yields fluctuated 23% around the average. Surprisingly, forb cover was a better predictor of biomass yield than warm-season grass with a positive correlation with biomass yield in the south and a negative correlation at other locations. Variation in land ethanol yield was almost exclusively due to variation in biomass yield rather than biomass quality; therefore, efforts to increase biomass yield might be more economical than altering biomass composition when managing conservation grasslands for ethanol production. Our measurements of bioenergy potential, and the factors that control it, can serve as parameters for assessing the economic viability of harvesting conservation grasslands for bioenergy. [ABSTRACT FROM AUTHOR]

Long-term crop rotation studies enable economic analyses that include a more complete representation of possible profit outcomes than do experiments of shorter duration. The objective of this study was to compare the profitability and risk of organic input (OI) and chemical input (CI) 4-yrcorn (Zea mays L.)-soybean [Glycinemax (L.) Merr.]-oat (Avenasativa L.)/alfalfa (Medicago sativa L.)--alfalfa crop rotations with a CI 2-yr corn-soybean rotation using yield and management data from an 18-yr experiment in southwestern Minnesota. Estimated production costs were matched with trial yields and commodity prices to calculate a distribution of net returns for each crop rotation. Cumulative distribution functions (CDFs) were constructed and compared using stochastic dominance. Average production costs for the CI 2-yr rotation were higher than those for the CI and OI 4-yr rotations ($488 ha-1, $405 ha-1, and $409 ha-1, respectively) though the OI rotation had higher machinery costs. The average net return for the CI 2-yr rotation was the highest of the three rotations analyzed when no organic price premiums were considered. However, when organic price premiums were applied, the average net return of the OI rotation was considerably larger than that of the CI 4-yr and 2-yr rotations ($1329 ha-1, $675 ha-1, and $846 ha-1, respectively), and the OI rotation was stochastically dominant to both CI rotations at all levels of risk aversion. [ABSTRACT FROM AUTHOR]

The article discusses a study which investigated the palatability and nutritive value of native legumes to sheep as well as their importance for prairie restoration and grazing in the Upper Midwest. Materials and methods included the establishment of a Waukegan silt loam soil in Saint Paul, Minnesota in 1997. Several charts are also presented, including one that shows height, growth stage, leafiness and palatability of perennial legumes as determined by sheep in 1998.

Restoration of native plant communities requires adapted germplasm; thus, information is needed to guide native seed collection and production. Analysis of genetic variation has potential to provide insight into diversity and relatedness of natural populations. Our objectives were to examine genetic diversity of native species in Minnesota to discover if variation is related to biomes or distance, and possibly to develop seed collection zones. Our study included prairie cordgrass (Spartina pectinata), purple prairie clover (Dalea purpurea), and spotted joe-pye weed (Eupatorium maculatum). Using amplified fragment length polymorphisms, we analyzed 100 samples from eight populations for prairie cordgrass, 152 samples from nine populations for purple prairie clover, and 127 samples from 10 populations for spotted joe-pye weed. We found moderate to high levels of genetic diversity within each species. Small populations were not necessarily lower in diversity than larger ones. Analysis of molecular variance results indicate clear population differentiation. However, rather than displaying geographic or ecological associations, the variation had discontinuous patterns. Therefore, we were not able to develop unambiguous recommendations for seed collection. We discuss the applicability of molecular markers in detecting adaptive potential. [ABSTRACT FROM AUTHOR]

The effects of alfalfa, red clover, and perennial ryegrass as cover crops on soybean cyst nematode (SCN) and soybean and corn yields were evaluated in Waseca, Lamberton, and Rosemount, MN. The cover crops were interseeded in soybean at 0 or 2 wks after planting soybean in 2002 and killed with herbicide before planting corn in 2003. As expected, SCN-susceptible soybean supported higher SCN population density than SCN-resistant soybean. Reduction of SCN population density by red clover (up to 40%) and alfalfa (up to 55%) was observed in some sampling occasions at Lamberton and Rosemount, probably due to reduced soybean growth, but the effect was inconsistent. No significant reduction of SCN population by the two crops was detected at Waseca. While perennial ryegrass did not affect SCN population density in most cases, up to 46% higher egg population densities were observed in the perennial ryegrass treatment as compared to the control at Waseca. SCN-resistant soybean produced higher yield than susceptible soybean at all sites. While alfalfa reduced soybean yield at Lamberton (up to 50%) and Rosemount (up to 11%), red clover and perennial ryegrass reduced soybean yield only at Lamberton (up to 38%) and Waseca (up to 34%), respectively. No difference in corn yield was observed at Waseca. At Lamberton, alfalfa and red clover planted at the time of planting soybean reduced corn yield in the following year 17 and 13%, respectively, and perennial ryegrass planted 2 wks after planting soybean reduced corn yield 13%. At Rosemount, significant reduction of corn yield was observed with red clover (15–21%) interseeded in SCN-susceptible soybean and with alfalfa (12%) and red clover (12%) interseeded in SCN-resistant soybean at the time of planting soybean. The results suggest that an even later planting date of cover crops in soybean may reduce yield loss due to competition and make these cover crops more appropriate for use in the soybean-corn rotation in Minnesota. [ABSTRACT FROM AUTHOR]

The article presents a study of seeding rate that affects the establishment of native perennial legumes or Fabaceae in the upper western U.S., conducted at Rosemount, Minnesota in 1999 and 2000. The species differed in population and yield response to seeding rates, with seeds cultivated of little bluestem or Poaceae. Illinois bundleflower and wild senna have the potential for biomass use than the purple prairie clover. The seeding-year populations increased linearly with the rise of seeding rate.

In the Upper Midwest, corn (Zea mays L.) and soybean (Glycine max [L.] Merr.) dominate the landscape, but only for six to seven months of the year. Thus, opportunities exist to establish crops that can utilize the remainder of the growing season and contribute to overall farm profitability. One species of interest is pennycress (Thlaspi arvense L.), but a lack of established agronomic best management practices is a barrier to successful crop production. The objectives of this study were to identify a range of cumulative growing degree days (CGDD) corresponding to pennycress physiological maturity, determine the optimal harvest window that maximizes pennycress seed yield and oil content, and characterize changes in pennycress seed attributes over seed maturation. This study was conducted over the 2016–2017 and 2017–2018 growing seasons with 'MN106' pennycress at two locations in Minnesota, USA. Seed dry weight stabilized within the window of maximum seed yield, but oil content did not maximize until after this period. However, there was minimal loss of oil content when pennycress was harvested within the seed yield maximization window. Based on these parameters, as well as seed moisture, it was estimated that pennycress reached physiological maturity between 2230 and 2250 °C d CGDD, or about a week prior to harvest maturity in terms of crop phenology. Delaying harvest to harvest maturity resulted in a 26% loss in harvestable seed due to seed shatter compared with the average maximum seed yield of 928 kg ha−1. Ensuring maximum pennycress seed yield and oil content at harvest is imperative to successful production and contribution to farm economic viability. • Parameters indicating pennycress physiological maturity maximized in a similar order, regardless of site-year. • Pennycress reached physiological maturity between 2230 and 2250 °C CGDD. • Seed moisture was too high at physiological maturity for mechanical harvest, so moisture reduction will be necessary to facilitate the earliest possible pennycress harvest. [ABSTRACT FROM AUTHOR]