Determining the Mechanism of Yield Stability in Alfalfa

Year-to-year stability of crop yields is important for farmers and, hence, is an important goal of plant breeding programs. Especially in perennial crops like alfalfa, farmers need to know that they can count on consistent yields over a period of three or more years. Alfalfa varieties are composed of a population of many genetically distinct plants (or genotypes), unlike corn hybrids or soybean lines, which are genetically uniform

Evaluation of brassicas for fall forage

Various species and varieties of brassicas were evaluated for their potential to extend the grazing season and provide forage through late-fall and early winter in Colorado. The species and varieties evaluated included: rapes (Bonar, Winfred, and Barnopoli), turnips (Appin, Barkant, and Purple Top), kale (Kestral), turnip x rape hybrid (Pasja), swede (Major Plus), and radish (Groundhog). Each species/variety combination was established on two different planting dates (mid-July and mid-August) with four replicates. In order to assess the potential of the brassicas as a source of forage during the fall and early winter, the varieties were sampled at two different times (mid-October and mid-November) for their yield and nutritional value (crude protein, neutral detergent fiber, and in-vitro dry matter digestibility). The second planting date yielded less biomass compared to the first. Crude protein content of the brassicas was high for most varieties (16 to 28%); whereas the fiber content was lower compared to grasses (20 to 35%); and as a result of this, the digestibility was also high (80 to 94%). Delaying the establishment date can constrain the dry matter yield of brassicas which reduces their potential to supply forage during the fall and early winter. The information obtained from this project has enabled us to pick four brassica varieties (Barnopoli rape, Pasja hybrid, Barkant turnip, and Groundhog radish) with potential to be included in forage systems with cool-season grasses and legumes.UCR::Vicerrectoría de Docencia::Ciencias Agroalimentarias::Facultad de Ciencias Agroalimentarias::Escuela de Zootecni

Establishing Birdsfoot Trefoil in the Mountain West

This bulletin describes birdsfoot trefoil in the Mountain West, and why it should be considered for planting. It includes cultivar selection and seeding rate, establishment considerations, and interseeding methods. Its high nutritive value and ruminant-friendly tannins will support livestock production without risk of bloat, while it fixes nitrogen to increase production in the entire pasture

Winter hardiness of \u3ci\u3eMiscanthus\u3c/i\u3e (III): Genome‐wide association and genomic prediction for overwintering ability in \u3ci\u3eMiscanthus sinensis\u3c/i\u3e

Overwintering ability is an important selection criterion for Miscanthus breeding in temperate regions. Insufficient overwintering ability of the currently leading Miscanthus biomass cultivar, M. ×giganteus (M×g) ‘1993–1780’, in regions where average annual minimum temperatures are −26.1°C (USDA hardiness zone 5) or lower poses a pressing need to develop new cultivars with superior cold tolerance. To facilitate breeding of Miscanthus, this study characterized phenotypic and genetic variation of overwintering ability in an M. sinensis germplasm panel consisting of 564 accessions, evaluated in field trials at three locations in North America and two in Asia. Genome‐wide association (GWA) and genomic prediction analyses were performed. The Korea/N China M. sinensis genetic group is a valuable gene pool for cold tolerance. The Yangtze‐Qinling, Southern Japan, and Northern Japan genetic groups were also potential sources of cold tolerance. A total of 73 marker–trait associations were detected for overwintering ability. Estimated breeding value for overwintering ability based on these 73 markers could explain 55% of the variation for first winter overwintering ability among M. sinensis. Average genomic prediction ability for overwintering ability across 50 fivefold cross‐validations was high (~0.73) after accounting for population structure. Common genomic regions for overwintering ability were detected by GWA analyses and a previous parallel QTL mapping study using three interconnected biparental F1 populations. One QTL on Miscanthus LG 8 encompassed five GWA hits and a known cold‐responsive gene, COR47. The other overwintering ability QTL on Miscanthus LG 11 contained two GWA hits and three known cold stress‐related genes, carboxylesterase 13 (CEX13), WRKY2 transcription factor, and cold shock domain (CSDP1). Miscanthus accessions collected from high latitude locations with cold winters had higher rates of overwintering, and more alleles for overwintering, than accessions collected from southern locations with mild winters

Biomass production of herbaceous energy crops in the United States: field trial results and yield potential maps from the multiyear regional feedstock partnership

Current knowledge of yield potential and best agronomic management practices for perennial bioenergy grasses is primarily derived from small-scale and short-term studies, yet these studies inform policy at the national scale. In an effort to learn more about how bioenergy grasses perform across multiple locations and years, the U.S. Department of Energy (US DOE)/Sun Grant Initiative Regional Feedstock Partnership was initiated in 2008. The objectives of the Feedstock Partnership were to (1) provide a wide range of information for feedstock selection (species choice) and management practice options for a variety of regions and (2) develop national maps of potential feedstock yield for each of the herbaceous species evaluated. The Feedstock Partnership expands our previous understanding of the bioenergy potential of switchgrass, Miscanthus, sorghum, energycane, and prairie mixtures on Conservation Reserve Program land by conducting long-term, replicated trials of each species at diverse environments in the U.S. Trials were initiated between 2008 and 2010 and completed between 2012 and 2015 depending on species. Field-scale plots were utilized for switchgrass and Conservation Reserve Program trials to use traditional agricultural machinery. This is important as we know that the smaller scale studies often overestimated yield potential of some of these species. Insufficient vegetative propagules of energycane and Miscanthus prohibited farm-scale trials of these species. The Feedstock Partnership studies also confirmed that environmental differences across years and across sites had a large impact on biomass production. Nitrogen application had variable effects across feedstocks, but some nitrogen fertilizer generally had a positive effect. National yield potential maps were developed using PRISM-ELM for each species in the Feedstock Partnership. This manuscript, with the accompanying supplemental data, will be useful in making decisions about feedstock selection as well as agronomic practices across a wide region of the country

Determining the Mechanism of Yield Stability in Alfalfa

Year-to-year stability of crop yields is important for farmers and, hence, is an important goal of plant breeding programs. Especially in perennial crops like alfalfa, farmers need to know that they can count on consistent yields over a period of three or more years. Alfalfa varieties are composed of a population of many genetically distinct plants (or genotypes), unlike corn hybrids or soybean lines, which are genetically uniform.</p

Interactions Among Western Ragweed and Other Sandhills Species After Drought

Interannual differences in yield and species composition of herbaceous vegetation on semiarid rangelands are common and often related to variations in precipitation regime. Interspecific interactions that occur after drought-induced population fluxes of western ragweed (Ambrosia psilostachya D.C.) were evaluated by removing western ragweed or associated species from 1-m2 quadrats at weekly intervals beginning in early May, June, or July 1991 or 1992 on high-seral sandhills prairie in Nebraska. The composite of peak standing crops for ragweed and each group of associated species was 77% greater during May–October 1991 (2 252 kg•ha-1) compared with 1992 (1 275 kg•ha-1) when April and May precipitation was 98 mm below average and a late frost occurred. Mean levels of western ragweed herbage up to 436 kg•ha-1 had no effect on associated species in 1991 when above average precipitation occurred throughout the growing season. In contrast, when an unusually dry spring occurred in 1992, relatively small mean levels of ragweed (189 kg•ha-1) reduced end-of-season standing herbage of rhizomatous C4 grasses on control plots by about 21% (137 kg•ha-1) with little effect on other associated species, regardless of when treatments were initiated. Within a given year, western ragweed density was seasonally constant, similar among treatments, and independent of preceding-year species composition. Severe defoliation of western ragweed had little effect on subsequent-year populations, indicating an ability to maintain primordia for several years with limited plant growth. Because western ragweed is not a strong competitor in the presence of vigorous graminoids, deferring use of June- or July-grazed pasture until after July in the subsequent year can minimize increases in western ragweed

Yield and Nutritive Value of Cool-Season Annual Forages and Mixtures Seeded into Pearl Millet Stubble

Cool-season annual forages can provide grazing for beef cattle during fall and early winter. Th e objective of this study was to evaluate yield and nutritive value of nine forage combinations seeded in early August into pearl millet (Pennisetum glaucum L.) hay stubble that was either sprayed or allowed to regrow. Grass species included spring triticale (×Triticosecale Wittmack), winter wheat (Triticum aestivum L.), and winter barley (Hordeum vulgare L.). Each grass was then combined with a brassica mixture {turnip [Brassicas rapa L. var. rapa], rape [Brassica napus L. var. napus], radish [Raphanus sativus var. oleifer Strokes], and hybrid Chinese cabbage [Brassica rapa L. chinensis) × Turnip]}. A legume mixture (hairy vetch [Vicia villosa Roth] and Austrian winter pea [Pisum sativum subsp. arvense L.]) was then added to the grass–brassica mixtures. All species and mixtures produced suffi cient forage (3080–5580 kg dry matter [DM] ha–1) to be stockpiled for fall grazing. Th e millet and brassicas dominated yield and nutritive value of the unsprayed and sprayed mixtures, respectively. Th e concentration of neutral detergent fi ber (aNDF) was greater in unsprayed than sprayed mixtures (510–579 and 229–246 g kg–1, respectively), but the concentrations of crude protein (CP) (169–180 and 185–202 g kg–1, respectively) and in vitro true digestibility (IVTD) (755–799 and 909–922 g kg–1, respectively) were less. Th e lesser nutritive value and yield potential associated with letting the millet regrow must be weighed against the extra inputs but greater yield potential and nutritive value when the regrowth is controlled prior to seeding.UCR::Vicerrectoría de Docencia::Ciencias Agroalimentarias::Facultad de Ciencias Agroalimentarias::Escuela de Zootecni

Interseeding cool-season forages into corn to increase yield and quality of residue grazed in the fall

Six forage species/mixtures were interseeded into irrigated grain corn to evaluate their yield and nutritional quality as a means of improving diets for beef cattle grazing cornstalks during the fall. Species evaluated included annual ryegrass (Lolium multiflorum), crimson clover (Trifolium incarnatum), Fridge winter triticale (X Triticosecale), a mixture of annual ryegrass plus crimson clover, a brassica mixture (Barkant turnip [Brassicas rapa], Barnapoli rape [Brassica napus], Groundhog radish [Raphanus sativus var.oleifer Strokes], and Pasja hybrid [Chinese cabbage {Brassica rapa L. chinensis} x Turnip hybrid]), and a mixture of winter triticale plus the brassica mix. The cool-season forages were interseeded at the V6 growth stage of corn on June 30, 2014. DM yield (p=0.0013), CP (p=0.0149), aNDF (p=0.0001), and in-vitro true digestibility (IVTD, p=0.0027) differed among the interseeded forages. Annual ryegrass and the brassica mix had the highest yields (596 and 790 kg ha-1, respectively). The CP content of all treatments was higher than that of cornstalks (5.2% vs. 18.3-26.1%) and had the potential to provide supplemental protein for beef cattle grazing corn residue. The fiber content of the interseeded cool-season forages was lower than cornstalks (73.5% vs. 23.4-44.2%), being particularly low in the brassica mix and the brassica mix plus winter triticale. Except for crimson clover (77.7%), all treatments had high IVTD values (89.492.1%), with all forages having higher values than cornstalks (57.7%). The cost per kg of DM and kg of CP of the interseeded forages varied widely because of differences in seeding rates, seed cost, DM yield, and CP content. Annual ryegrass and the brassica mix were the treatments with the lowest costs ($0.18 and$0.17 kg-1 of DM and $0.96 and$0.72 kg-1 of CP; respectively), having values similar to good quality alfalfa hay with a current market price of $154 t-1. Interseeding cool-season forages can increase the quality of biomass offered to beef cattle grazing cornstalks during the fall. This should be combined with strip grazing to maximize utilization of the high quality cool-season forages that can grow during the fall. This practice can reduce supplementation costs for producers while improving nutrient cycling through a more even spread of manure across the field.UCR::Vicerrectoría de Docencia::Ciencias Agroalimentarias::Facultad de Ciencias Agroalimentarias::Escuela de Zootecni

Forage Brassicas Stockpiled for Fall Grazing: Yield and Nutritive Value

Forage brassicas can potentially be used to extend the grazing season into the fall for beef cattle operations, thereby reducing input costs. Nine cultivars of forage brassicas were seeded on two planting dates, and their yield and nutritive value were measured for two fall harvest dates over 2 years in northern Colorado. Cultivars evaluated included three turnips (Brassica rapa L.; Purple Top, Barkant, and Appin); three rapes (Brassica napus L.; Winfred, Barnapoli, and Bonar); Groundhog radish (Raphanus sativus L.); Major Plus swede [Brassica napobrassica (L.) Mill.]; and Pasja hybrid (Chinese cabbage [Brassica rapa subsp. chinensis (L.) Hanelt] ´ turnip hybrid). Dry matter (DM) yield, crude protein (CP), neutral detergent fiber (aNDF), and in vitro true digestibility (IVTD) were evaluated using a three-way factorial treatment structure. Planting date was the overriding factor impacting DM yield with an overall reduction of 3770 lb/acre by delaying planting until mid-August. Additional forage was also obtained by delaying the harvest date until mid-November, but the increase was minor compared with yields obtained with earlier planting. The rapes tended to yield the highest when seeded in mid- to late July, but there were only minor differences among cultivars seeded in mid-August. Fiber content of forage brassicas was low (19.0–25.2%), and CP content (18.6–25.5%) and IVTD (85.5–92.9%) were above the requirements for all classes and stages of beef cattle. Forage brassicas had minor changes in nutritive value during the fall, which makes them suitable for stockpiling when combined with lower-quality forages to dilute their high nutrient content and thereby minimize the potential for rumen upset.UCR::Vicerrectoría de Docencia::Ciencias Agroalimentarias::Facultad de Ciencias Agroalimentarias::Escuela de Zootecni