In May 2017, the cover crop breeding network met to identify plant species and traits that would be evaluated and improved for use as cover crops across the U.S.
During the past year, the Noble Research Institute Small Grains Breeding Laboratory, led by Xuefeng Ma, Ph.D., in Ardmore, Oklahoma, has been collecting new germplasm; screening germplasm; conducting yield trials; and making new crosses of rye, triticale and oat for improving cover crop performance.
As of now, the major traits being selected for include:
Below are the major activities for each crop, as reported by Xuefeng Ma, Ph.D.
During the 2016-2017 season, we made 800 half-sibling crosses and selected 200 of them for further evaluation. We also planted 250 rye entries in preliminary yield trials and 60 entries in advanced yield trials to evaluate for cover crop traits and yield.
For the 2017-2018 season, we planted 200 rye entries for further yield evaluation. We also planted 400 Elbon entries for the second cycle of recurrent mass selection for disease resistance, quick ground coverage and high biomass. In addition, we planted 600 individually spaced plants from a population from North Carolina selected for allelopathy. However, this trial was not successful due to poor seed germination from old seed stock.
In addition, we maintained isolated seed increase cabins to ensure seed supply for all testing sites under the FFAR cover crop network.
We have been screening oat plants for cold tolerance during the last a few years. By 2017, we were able to narrow 1,800 accessions from the national Germplasm Resources Information Network (GRIN) to 80 entries, which will be the core germplasm for making new crosses in future years. In 2017 and 2018, we screened the Oat F4:5 family in the field for winter tolerance and yield.
In addition, we have been actively collecting black oat germplasm. In total, we have collected 123 black oat accessions from GRIN, 45 from the IPK gene bank in Germany, and 11 from other sources involving origin from several countries. Most black oat accessions will be increased for seed during 2018 before further evaluation.
The triticale germplasm and research populations have been significantly expanded since last season. In 2016-2017, we screened 620 winter triticale accessions and retained 400 of them for further field evaluation.
In 2017-2018, we planted 1,300 spring triticale accessions for first-year field screening. We planted six double haploid populations, involving 900 lines, for seed increase and to collect data on first-year traits. The double haploid populations will be used for genomics studies and QTL mapping of cover crop traits in the next a few years. In addition, triticale crosses are ongoing in the greenhouse.
Wheat is not the focus of breeding for cover crops, but it has the most valuable genomics resources for other small grains. QTL and genes discovered in wheat can be used for triticale and rye improvement.
Since 2017, a winter wheat association mapping panel has been used for QTL discoveries on several traits, such as seedling heat tolerance and drought tolerance. These traits contribute to early vigor and quick establishment of small grain cover crops. The QTL studies will be continued in 2018.
The legume cover crop breeding team is made up of Suresh Bhamidimarri, Ph.D., of the Noble Research Institute Legume Breeding Laboratory in Ardmore, Oklahoma, and Steven Mirsky, Ph.D., of the U.S. Department of Agriculture Sustainable Agricultural Systems Laboratory in Beltsville, Maryland.
In the past year, the team selected hairy vetch, crimson clover and Austrian winter pea breeding materials to be incorporated into this project.
Below are updates reported by Suresh Bhamidimarri, Ph.D., and Steven Mirsky, Ph.D.
In Ardmore, Oklahoma, we evaluated 12 lines (six replicates) of hairy vetch for:
In Beltsville, Maryland, we planted 27 populations in 2017 and evaluated them for:
Tentatively, we expect to advance seven of these Maryland populations to next year.
Bhamidimarri’s group in Ardmore, Oklahoma, obtained 60 accessions from the national germplasm resources information network (GRIN), which will be planted in the 2018-2019 season.
In Beltsville, Maryland, we planted 20 populations in 2017 and evaluated them for:
Tentatively, we expect to advance five of these populations to next year.
In Beltsville, Maryland, we planted 139 lines in 2017 and evaluated them for:
Tentatively, we expect to advance 12 of these lines to next year.
The Noble Research Institute Agronomy Sensor Laboratory, led by Twain Butler, Ph.D., planted 3,745 accessions from the national germplasm resources information network (GRIN) at the Noble Research Institute’s Red River Farm in Love County, Oklahoma. These plants will be screened for:
A commercially available check from each species was included as a standard check to determine if any of the GRIN lines were superior to existing cultivars.
The 2017-2018 growing season had 12 days with the low temperatures of below 20 degrees Fahrenheit. The absolute low temperature reached 2 degrees, which will provide a good test for screening accessions susceptible to freezing temperatures.
We planted 125 GRIN accessions, of which 12 were visually equal to or better than the “Commander” check cultivar based on fall vigor. These accessions averaged 60 percent freeze damage.
We planted 658 GRIN accessions, of which 28 GRIN accessions were visually equal to or better than the “Graza radish” check cultivar based on fall vigor. These accessions averaged 85 percent freeze damage.
We planted 128 GRIN accessions. No commercial check was available. Several accessions appeared to have good fall vigor, however all accessions appears to be winter-killed (99 percent).
We planted 620 GRIN accessions, of which 19 were visually equal to or better than the “Dwarf Essex Rape” check cultivar based on fall vigor. These accessions averaged 25 percent freeze damage.
We planted 78 GRIN accessions, of which 57 were visually equal to or better than the “Carinata” check cultivar, however all accessions appear to be winter-killed (99 percent).
We planted 412 GRIN accessions, of which 163 were visually equal to or better than the “Florida Broadleaf” check cultivar, however all accessions experienced significant (90 percent) freeze damage.
We planted 90 GRIN accessions, of which seven were visually desirable based on fall vigor and freeze damage ratings. These accessions averaged 35 percent freeze damage.
We planted 835 GRIN accessions, of which 19 were visually equal to or better than the “Seven Top Turnip” and “Winifred” check cultivars. These accessions averaged 30 percent freeze damage.
We planted 799 accessions. Due to environmental conditions (sand storm) and location within the field (border affect), we need to repeat the B. oleracea trial. Most of the accessions died prior to freezing temperatures, preventing us from making valid conclusions relative to the “Impact Collard” and “Dwarf Siberian Kale” check cultivars.
The Noble Research Institute Genome Editing Laboratory, led by Zengyu Wang, Ph.D.,* identified three separate genes (KCS12, HS1, QHS1) in Medicago truncatula related to hardseededness. These will serve as candidate genes in hairy vetch. We will develop genome editing technology to knockout the gene controlling hardseededness in hairy vetch and produce plants with soft seeds.
To develop an effective genome editing system, we first need to establish a plant regeneration system in hairy vetch.
We have taken two approaches to establish such a system:
This sets a basis for developing genome editing techniques in hairy vetch. We initiated whole genome sequencing and generated 120 GB of sequence data. We are in the process of assembling this data that would identify genes that govern agronomic traits like hardseededness, etc. After data assembly and analysis, we will have the needed contig and scaffold information to provide us the basic knowledge of the hairy vetch genome.
*Zengyu Wang, Ph.D., retired from the Noble Research Institute at the end of 2018. This work will be carried on by Amr Ibrahim, Ph.D., postdoctoral fellow in the Legume Breeding Laboratory, led by Suresh Bhamidimarri, Ph.D.