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This study chronicles the ongoing process to domesticate an interspecific trigenomic tetraploid hybrid sunflower derived from a series of interspecific crosses between Helianthus annuus and Helianthus tuberosus. The goal of this process is to develop a perennial oilseed crop that can produce both high value vegetable oil and continuous ground-cover. Selection has focused on developing an ideotype with the domesticated morphology of H. annuus and the below-ground perennial features of H. tuberosus. The overarching challenge in the process of breeding and domesticating this interspecific perennial sunflower is overcoming obstacles associated with interploid meiosis in order to resolve a chromosomally stable hybrid population. As selection progresses through generations of intermating, there are improvements toward the desired ideotype, but selection efficiency is slowed by apparent antagonisms between annual- and perennial morphological targets and irregular meiosis which is especially problematic in a trigenomic tetraploid. This shows that keys toward perennial crop development through interspecific hybridization will be to capitalize on the abundant phenotypic variation within our population, achieve meiotic stability in order to maximize selection efficiency, and to break genetic correlations between annual and perennial traits. [ABSTRACT FROM AUTHOR]

Flaxseed has gained popularity as a health food. Wild, perennial Linum relatives of annual flax (L. usitatissimum) possess similar oil compositions, making them perennial oilseed (OS) alternatives. The objective of this study was to phenotype 25 OS and 17 cut flower (CF) breeding populations with 137 wild Linum species' accessions in a common garden over three years (Y1–3) to quantify the impact of selection and identify top candidates. This study was intercepted by COVID-19, which prevented the same detailed phenotyping of Y1 from occurring in Y2–3. Traits measured from the perennial flax OS, in comparison with the CF ideotypes: weekly seed germination (Y1), yield per plant (Y1–3), seed weight (Y1–2), shattering (Y1–2), and seed capsule diameter (Y1). In Y1, OS selections had the highest yield per plant, followed by L. austriacum and then CF selections. The 1000 seed weights in Y1 were highest in annual flax, followed by L. grandiflorum and L. baicalense. Seed numbers/capsule were low in Y1–2, possibly due to shattering. Average yield per plant increased across Y1–3 indicating that, once plant establishment had occurred along with the potential for two harvests/year in Y2 onwards, significant OS yield can be realized. Harvest 1 yields were significantly higher than in harvest 2. In Y1–3, OS selections had the highest average seed yield. In Y1, OS and CF populations had smaller seeds, higher shattering, smaller capsule diameters, and lower germination than wild species. Significant breeding efforts are needed to increase perennial flax yield, using the multiple crop ideotypes. [ABSTRACT FROM AUTHOR]

(1) Background: Annual flax (Linum usitatissimum) and many wild relatives possess showy blue flowers and finely textured foliage. To promote the use of blue-flowered flax as ornamentals, an herbaceous perennial flax breeding program was initiated to develop ideotypes and test their effectiveness. The objectives of this study were to (a) compare traits of interest for herbaceous perennials in breeding populations (CF, oilseed) and accessions of annual/perennial species in a common garden; (b) quantify the impact of selection (direct, indirect) for traits of interest; (c) identify top candidate species for continued breeding using the herbaceous perennial flax crop ideotype; (2) Methods: Recorded traits, based on the perennial flax ideotype, included: flower diameter, flowering period, stem length and diameter, plant width and height, summer and winter survival; (3) Results: OS and CF populations had smaller stem diameters, longer flowering periods, larger plant size, more uniform growth, and improved winter survival compared to wild species. Linum austriacum was the top wild species for the CF breeding ideotype but comparable in performance with L. perenne for the herbaceous perennial flax ideotype; (4) Conclusions: The effect of 1–5 yrs. on selection for target/non-target traits in wild species for future R&D is exemplified with selection and release of an herbaceous/garden ornamental perennial flax for the market. [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]

The genus Linum L. contains ≈200 primarily blue-flowered species, including several ornamentals, yet no reports exist regarding the cut flower potential of this genus. The objective of this study was to evaluate the cut flower potential of perennial flax cultivars (L. perenne L. 'Blue Flax' and 'Sapphire'; Expt. 1, 2018) and accessions (L. austriacum L., L. lewisii Pursh., and L. perenne; Expt. 2, 2019), and record traits that will enable breeding and selection for improved cut flower performance. The mean vase life across both cultivars in Expt. 1 was 9.2 days. In Expt. 2, L. perenne had the longest average vase life (9.3 days), followed by L. austriacum (9.1 days) and L. lewisii (8.3 days). The floral preservative (Floralife 300) significantly increased vase life by an average of 1.7 days in Expt. 1, and 1.6 days in Expt. 2, and resulted in a significantly greater number of flowers (≈2x) in both experiments. Significant variation was observed among genotypes for most traits, including vase life (6.2 to 11.3 days) and number of flowers (1.3 to 10.5), highlighting the opportunities for improving the potential of cut flower perennial flax through breeding. [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]

Flaxseed (Linum usitatissimum) has recently grown in popularity as a health food due to its high levels of omega-3 fatty acids. Many undomesticated Linum species possess a similar oil profile, in addition to perenniality, and could, therefore, provide similar products in addition to ecosystem services such as soil retention, improvements in water quality, and pollinator services. Many Linum species also possess ornamental qualities, e.g., blue flowers, which could provide added value as a new cut flower crop or garden herbaceous perennial. A perennial flax breeding program will be initiated by screening of Linum accessions for key agronomic and horticultural traits. Herein, we outline an ideotype approach which will enable identification of top herbaceous perennial candidates for domestication based on qualities relevant to oilseed, cut flower, and garden herbaceous perennial crop uses. In this review, we summarize the concept of ideotype breeding as it relates to perennial crop domestication and outline considerations for ideotype design. The tools outlined herein should prove useful to other breeders and especially for undomesticated crops. Whether the ideotype concept is applied as a framework for selection or simply as a means of generating hypotheses, applying this approach can provide structure to breeding programs with complex objectives. [ABSTRACT FROM AUTHOR]