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Silflower (Silphium integrifolium Michx.) has been identified as a candidate for domestication as a perennial oilseed crop. In order to successfully domesticate silflower it will be necessary to identify traits that should be targeted for selection. We have conducted the first multilocation trial of replicated silflower genotypes at six sites across four states. By observing architectural, phenological, and yield traits in a diversity panel of silflower breeding material, we were able to estimate the heritability of these traits, as well as patterns of correlation across years and environments. We found that this population expressed heritable variation for many, but not all, traits of interest, and that targeted introgression of diversity may be beneficial for some traits. In addition, we used regression analysis to identify several traits, particularly height, number of stalks per plant, and stalk diameter as important contributors to determining levels of yield and levels of lodging. These results will help to guide future silflower domestication efforts and have already shaped the direction of our breeding program. Core Ideas: Silflower is being domesticated as a perennial oilseed crop to provide ecological benefits. It is unclear which traits are highest priority for improvement. A diversity panel was evaluated at six sites for several architectural, phenological, and yield traits. Estimates of heritability, variation between locations and year, and trait correlations will inform selection. [ABSTRACT FROM AUTHOR]

Species diversity can increase natural grasslands productivity but the effect of diversity in agricultural systems is not well understood. Our objective was to measure the effects of species composition, species richness, and harvest management on crop and weed biomass in perennial herbaceous polycultures. In 2003, 49 combinations of seven species (legumes, [C.sub.3] and [C.sub.4] grasses) including all monocultures and selected two to six species polycultures were sown in small plots at two Iowa, USA, locations in a replicated field design. Plots were split in half and managed with either one or three harvests in each of 2004 and 2005. Biomass increased log-linearly with species richness in all location-management environments and the response was not different between managements. Polycultures outyielded monocultures on average by 73%. The most productive species in monoculture for each management best explained the variation in biomass productivity. The biomass of plots containing this species did not increase with richness in most environments but biomass of plots without this species increased log-linearly in all cases. Weed biomass decreased exponentially with richness in all environments. On average, increasing species richness in perennial herbaceous polycultures increased productivity and weed suppression, but well-adapted species produced high biomass yield regardless of richness.

Intermediate wheatgrass [IWG; Thinopyrum intermedium (Host) Barkworth & D.R. Dewey] is a perennial cereal and forage crop marketed for its grain, Kernza. Lodging, which is correlated with plant height, can reduce IWG grain yield. Our goal was to determine the effects of the plant growth regulator trinexapac-ethyl (TE) application rate; forage harvest timing; and N rate on IWG plant height, lodging, aboveground biomass, grain yield, and harvest index. The experiment was established in 2015 in southern Wisconsin using a population of IWG bred for increased grain yield. The experimental design was randomized complete blocks with three replications of a factorial arrangement of three factors: TE rate (0, 0.22, 0.66 kg a.i. ha-1), forage harvest timing (unharvested, summer, summer + fall, spring + summer + fall), and N rate (90 and 135 kg N ha-1). Responses were measured in the second (2017) and third (2018) production years of IWG. Lodging was not observed. No interactions among treatment factors were detected. Plant height was 6% lower, grain yield was 26% higher, and harvest index was 48% higher in the low TE rate treatment compared to non-treated, averaged across other factors. Harvesting forage in the spring + summer + fall reduced plant height by 7% compared to unharvested control but reduced grain yield by 11%. The high N rate increased plant height by 4% and grain yield by 26%. Using TE can be a viable strategy to reduce plant height and increase grain yield in IWG dual-use (grain and forage) production systems. [ABSTRACT FROM AUTHOR]

Kernza® intermediate wheatgrass (Thinopyrum intermedium) is a novel perennial grain and forage crop with the potential to provide multiple ecosystem services, which recently became commercially available to farmers in the USA. The viability and further expansion of this promising crop require understanding how it may fit the needs of farmers' livelihoods and the structure of their farming systems. However, no prior research has studied the perceptions and experiences of Kernza growers. The goals of this research were to understand why farmers grow Kernza, how Kernza fits into their systems and identify challenges for future research. We conducted in-depth interviews with ten growers in the North Central USA during the summer of 2017, who accounted for a third of the Kernza farmers in the USA at the time. All farmers had a positive attitude toward experimentation and trying new practices, and they were interested in Kernza for its simultaneous ecological and economic benefits. Kernza was marginal in terms of area, quality of fields and resources allocated in the farm systems, which also meant that farmers maintained low costs and risks. Growers utilized and valued Kernza as a dual-use crop (grain and forage), sometimes not harvesting grain but almost always grazing or harvesting hay and straw for bedding. Weeds were perceived as a challenge in some cases, but Kernza was valued as a highly weed-suppressive crop in others. Farmers requested information on optimal establishment practices, assessment of forage nutritive value, how to maintain grain yields over years, weed management, markets and economic assessment of Kernza systems. These results agree with other cases on sustainable practices adoption showing that engaging farmers in the research process from the beginning, identifying knowledge gaps and testing management alternatives are critical for the success and expansion of novel agricultural technologies. [ABSTRACT FROM AUTHOR]

Intermediate wheatgrass [IWG; Thinopyrum intermedium (Host) Barkworth & D.R. Dewey] is a cool‐season perennial forage grass bred for higher seed yield. It is the first perennial grain crop in the United States, commercialized as Kernza since 2015. Managing IWG as a dual‐use grain and forage crop could provide several ecosystem services including conserving soil and clean water while increasing economic income to growers. However, little is known about the weed management risks associated with IWG. Therefore, we studied weed community composition, biomass, IWG grain, and aboveground biomass in a factorial experiment with two weed management treatments, two nitrogen fertilization rates, and four forage harvest schedules (no harvest, summer only, summer + fall, and spring + summer + fall). Over three production years, weed biomass decreased by 88% regardless of treatment, and the weed community composition changed from predominantly winter annual to perennial species. In the second and third production years the weed community composition remained relatively stable. Grain yield was 16% greater with 135 kg N ha−1 than 90 kg N ha−1 but was not affected by in‐season forage harvest or weed management treatments in the second and third years. Grain yield decreased from 763 to 371 kg ha−1 over three years, while aboveground biomass remained stable. Weed presence did not affect yields in second and third years. Dual‐use IWG cropping systems effectively suppressed weeds and IWG is a promising grain crop alternative for farmers interested in diversifying their cropping systems under similar conditions. [ABSTRACT FROM AUTHOR]

Core Ideas: Oat forage harvested in late heading increases yield and milk production per hectare.Oat cultivar Laker reached boot and heading 3‐4 days earlier than ForagePlus.Thermal units (GDD) should be used to report maturity time instead of calendar date. Oat (Avena sativa L.) is a widely used forage crop in the USA and globally, often integrated in dairy systems where it provides the benefits of diversifying crop rotations. As the forage harvest occurs at a later date, forage yield is expected to increase while nutritive value is expected to decrease. To determine the optimal maturity stage to maximize milk production, a 2‐year experiment with two forage‐oat cultivars (ForagePlus and Laker) and four harvest times (boot stage, 2 days after boot stage, heading, and 5 days after heading) was established in a randomized complete block design with three replications at two locations in Wisconsin, USA. Laker reached the boot stage 4 days earlier and headed 3 days earlier than ForagePlus. Relative forage quality decreased at the same rate with increasing growing degree‐days for both locations, years, and cultivars. Therefore, to maximize milk production per cow through feeding the highest nutritive value forage, harvesting oat at boot stage is recommended. Forage yield increased linearly with increasing growing degree‐days for both locations, years, and cultivars, with steeper slope in Arlington than Madison due to precipitation differences. Model estimates of milk production per hectare in both cultivars increased linearly across the four harvest dates in Arlington. In Madison, milk production per hectare did not change significantly with harvest date. Harvesting oat for forage at late heading can therefore increase milk production per hectare, since the greater forage yield compensates for the reduction in forage nutritive value. [ABSTRACT FROM AUTHOR]

Resilient, stable, and productive forage systems are needed to endure increasingly frequent climatic extremes. Resilience is the ability of a forage system to withstand a climatic crisis with high yields, stability is the minimal variability of yields across normal years, and productivity is the average yield across normal years. The goal of this research was to quantify resilience, stability, and productivity of alfalfa (Medicago sativa L.) cultivars to identify superior ones. Forage yield means from alfalfa cultivar trials from 11 US states and one Canadian province over 19 yr (1995–2013) were analyzed using linear mixed models. Locations with an extreme crisis year were identified, and quantitative measures for resilience and stability for each cultivar were calculated. Productivity, stability, and resilience were different among cultivars across locations, showing that some cultivars were consistently superior for each variable. Cultivar stability was not associated with productivity, and it was negatively associated with disease resistance. Cultivar resilience was negatively associated with productivity, and not associated with other traits. Cultivar productivity has increased with year of release of cultivar, stability has not changed, and resilience has decreased. Therefore, stability and resilience are different dimensions, explained by different traits. A coordinated evaluation effort across locations is needed to test and improve cultivar resilience in the future, and develop alfalfa cultivars more profitable for the long term. [ABSTRACT FROM AUTHOR]

Intermediate wheatgrass (IWG) is a new perennial dual-use crop for grain and forage with growing interest among farmers. Intercropping IWG with red clover may increase yield and nutritive value through nitrogen transfer. IWG and red clover planting timing can affect grain and forage yield, and there has not been previous research on this management practice. At two locations (Arlington and Lancaster, WI, USA) a factorial experiment was established two years with two factors: (1) IWG planting date (August through October, and April) and (2) red clover planting season (in the fall with IWG or frost seeded in the next spring). Yield data were collected for two subsequent years. Grain yield was maximized at 515 kg ha−1 and 423 kg ha−1 at Arlington and Lancaster when planted by 26 August and 13 September, respectively. Planting date influenced grain yields in the first harvest year but not in the second. Seeding red clover in the spring increased IWG and red clover biomass compared to seeding it in the fall. In Wisconsin, planting IWG by early September at the latest and planting red clover in the spring is recommended to maximize grain yield. [ABSTRACT FROM AUTHOR]

Resilience is increasingly part of the discussion on climate change, yet there is a lack of breeding for resilience per se. This experiment examined the genetic parameters of a novel, direct measure of resilience to water deficit in tall fescue (Lolium arundinaceum (Schreb.) Darbysh.). Heritability, genetic correlations, and predicted gain from selection were estimated for average productivity, resilience, and stability based on forage mass of a tall fescue half-sib population grown under a line-source irrigation system with five different water levels (WL). Resilience was both measurable and moderately heritable (h2 = 0.43), with gains of 2.7 to 3.1% per cycle of selection predicted. Furthermore, resilience was not correlated with average response over environments and negatively correlated with stability, indicating that it was not a measure of responsiveness to more favorable environments. Genetic correlations among WL ranged from 0.87 to 0.56, however in contrast, resilience was either not or slightly negatively genetically correlated with WL except for moderate correlations with the 'crisis' WL. Thus, breeding for improved resilience was predicted to have little effect on forage mass at any given individual water deficit environment. Overall, results indicated that this novel metric could facilitate breeding for improved resilience per se to water deficit environments. [ABSTRACT FROM AUTHOR]

• Intermediate wheatgrass (IWG) RFQ was 175 in spring, 65 in summer, and 116 in fall. • The ttNDFD of IWG monoculture was 0.53 in the spring and 0.40 in summer and fall. • Spring and fall forage are suitable for beef and dairy cows, and growing heifers. • Intercropping Kernza IWG with red clover increases forage nutritive value in the fall. Kernza intermediate wheatgrass is the first perennial grain crop in the world and has been developed with conventional breeding to increase seed yield of forage intermediate wheatgrass (Thinopyrum intermedium (Host) Barkworth & D.R. Dewey). When managed for dual-use (grain and forage), Kernza intermediate wheatgrass can produce grain, crop residue (straw) in the summer, and green forage in the spring and fall. Mixtures of this grass with legumes could increase forage yield and nutritive value and provide other environmental and economic benefits. Despite the growing interest in these dual-use production systems, forage nutritive value of Kernza intermediate wheatgrass forage in a dual-use system in the Upper Midwest is unknown. A replicated field experiment was established in two locations in southern Wisconsin (Arlington and Lancaster) with two treatments: Kernza intermediate wheatgrass grown in monoculture and mixture with red clover (Trifolium pratense L.). Forage samples were collected at late vegetative stage in the spring, at grain harvest in the summer, and at the end of the regrowth period in the fall. Forage nutritive value of the monoculture was greatest in the spring with 456, 249 and 225 g kg−1 for neutral detergent fiber (NDF), acid detergent fiber (ADF) and crude protein (CP), respectively; lowest in the summer with 702, 427 and 51 g kg−1 NDF, ADF and CP, respectively, and intermediate in the fall with 590, 337 and 119 g kg−1 NDF, ADF and CP, respectively. Predicted total-tract neutral detergent fiber digestibility (ttNDFD) was 0.53 for the spring forage and averaged 0.37 for the summer and fall forage, with no differences between the mixture and monoculture. The relative forage quality (RFQ) for the monoculture was 175 for the spring forage, 65 for the summer residue, and 116 for the fall. Intercropping red clover with Kernza intermediate wheatgrass increased CP of the summer crop residue by 69%, and increased CP and RFQ of the fall forage by 49% and 11%, respectively, while reducing NDF and ADF of the fall forage by 25% and 18%, respectively. Therefore, Kernza intermediate wheatgrass forage is suitable for lactating beef cows, dairy cows, and growing heifers when harvested in the spring and fall, and it offers high potential for dual-use grain and forage systems. [ABSTRACT FROM AUTHOR]