Identifying regionally adapted winter pea varieties for use as grain, forage, and cover crops

Rachel Atwell, Graduate Student, Crop Science
Chris Reberg-Horton, Associate Professor, Crop Science
Miguel Castillo, Assistant Professor, Crop Science
Steven Mirsky, Research Ecologist, USDA-ARS

Winter pea has desirable attributes for use as a grain, forage, and cover crop on organic farms in the Southeast. Winter pea has high protein content, ranging from 15-35%, and can serve as a protein source in livestock feed rations, thereby reducing reliance on highly priced soybean meal. Unlike soybeans, heat processing is not necessary for winter pea prior to livestock consumption (Cash et al., 1995), allowing for direct feeding. Winter pea yield has been shown to increase when grown in mixture with wheat, as opposed to growth in monoculture (Murray and Swensen, 1985). In addition to yield increases, reduced Sclerotinia pressure has been observed when peas were grown in mixture with wheat as opposed to growth in monoculture (Murray and Swensen, 1985). In addition to value as a grain crop, winter pea also has potential for use as a forage and cover crop in the Southeast. Research from this past growing season in North Carolina indicates that some winter pea genotypes have the potential to produce high biomass and winter pea can be easily terminated, two desirable benefits for use as a cover crop.

A field screen of available winter pea genotypes has not occurred in the Southeast and farmers are limited to using varieties which have been developed in other U.S. regions. Field screening of available winter pea germplasm will allow for identification of genotypes that experience maximum growth potential in the Southeast and catalyze regionally adapted variety release.

Research was conducted in Clayton, Kinston, and Salisbury, North Carolina from 2014-2015. Nineteen winter pea genotypes were evaluated in monoculture and in mixture with different wheat maturities commonly planted in North Carolina.

Picture 1. One winter pea genotype of the nineteen evaluated had poor cold tolerance across all locations.

Some winter pea genotypes included in the trial are winter pea varieties available in other parts of the U.S., while some are advanced lines in Dr. Rebecca McGee’s program, a USDA legume breeder in Pullman, WA. The standard winter pea available in North Carolina was also evaluated for comparison purposes. Research plots were established in early-mid October 2014 using a small plot grain drill set on 7 inch row spacing. Winter peas were evaluated for cold tolerance, disease resistance, biomass production, and grain yield. Harvest occurred during June 2015.

Picture 2. Sclerotinia pressure at the Salisbury, NC location in a winter pea monoculture plot.

Results from the first year of this research trial indicate that there is promise for winter pea production in North Carolina. Eighteen of the winter pea genotypes included in the study had excellent winter survival during the winter of 2014-2015, with only one winter pea genotype lacking the cold tolerance to survive the North Carolina winter. Disease pressure was minimal at the Clayton location. Both Ascochyta leaf blight and Sclerotinia blight were observed at the Salisbury location, however overall low pressure from each disease was observed across winter pea genotypes at this location. At the Kinston location, most winter pea genotypes had very poor survival due to strong Sclerotinia pressure.

Picture 3. Winter pea growth up wheat during April 2015 in Clayton, NC.

Visual ratings indicated that several winter pea genotypes included in the trial have promise for use as a cover crop due to high biomass production. Cover crop biomass data will be collected and analyzed for nutrient content during the 2015-2016 winter pea growing season. All wheat varieties included in the study reached maturity prior to all winter pea genotypes. Grain was harvested in mid-June using the soybean sieve in a research combine. Grain was harvested for both winter pea monocultures and winter pea/wheat mixtures with minimal grain loss.

Picture 4. A high biomass producing winter pea genotype growing up wheat.

Yield results were only obtained from the Clayton location. Results from this location indicate that some winter pea genotypes experience higher grain yield when grown in monoculture while others produced higher grain yield when grown in mixture with wheat. Results from this location indicate that many winter pea genotypes included in the study have the potential to out-yield the winter pea variety currently available in North Carolina. Grain yield data from additional locations and years in North Carolina is necessary before reliable grain yield data can be provided.

Additional research trials will be conducted over the next several winter growing seasons to expand upon results obtained in the first year of this trial. Replications of the grain trial conducted in 2014-2015 were established in Clayton, Kinston, and Salisbury, NC during October 2015. Two additional trials were also established in October 2015. One will evaluate the same winter pea genotypes in monoculture and in mixture with oats, barley, and wheat for use as a forage and cover crop. Winter pea biomass will be collected and samples will be analyzed for nutrient content and forage quality. The other trial established will evaluate available winter pea varieties throughout the United States for grain yield in North Carolina.

Picture 4. A high Picture 5. A semi-dwarf winter pea genotype which did not climb up wheat. Some of the shorter winter pea genotypes evaluated in the trial were the higher yielding genotypes, indicating different growth habits may be preferably for use as a grain and cover crop.

References
Cash, D., J. Sims, H. Bowman, and B. Smith. 1995. Growing Peas in Montana. Montana State
University.
Murray, G.A., and J.B. Swensen. 1985. Seed yield of winter field peas intercropped with winter
cereals. Agron. J., 77:913-916.

Picture 6. Winter pea grain harvest during June 2015 at the Salisbury location.