Project Number: 2090-21000-035-08-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Aug 1, 2018
End Date: Jul 30, 2019
1) Determine quality and stage of maturity at first harvest of 200 alfalfa varieties at four locations in the Pacific Northwest. Fall dormancy and yield for all cuttings will be determined to identify and reduce confounding factors with quality. 2) Quantify the genetic diversity of alfalfa that is related to forage quality to understand the potential to breed new alfalfa varieties for higher forage quality. 3) Identify molecular markers associated with forage quality (NDF, NDFD24, NDFD30, NDFD48, kd, iNDF, TTNDFD) traits in alfalfa to aid alfalfa breeders. 4) Extend the knowledge gained from project to positively impact alfalfa producers, breeders and others in the alfalfa industry.
Four locations have been selected to conduct the field research in the Pacific Northwest and include Prosser, Washington, Union, Oregon, and Twin Falls, Idaho, representing a diversity in western elevation and latitude with different climatic and edaphic conditions. Alfalfa seed has been requested from all major seed companies to be used in the experiment with a maximum of 25 varieties per company with the company deciding which to enter. The remainder of the varieties will come from USDA Agricultural Research Service National Plant Germplasm System (NGPS) Temperate-adapted Forage Legume Genetic Resources Program. A criterion used to define the ‘diverse set of germplasm’ varieties includes accession collection site/geographic location (latitude/longitude), evaluation data on accessions, whether an accession belongs to the alfalfa core collection, and the group number assigned to the collection (Basigalup et al., 1995). All information associated with accessions will be queried to identify our diverse panel can be accessed through the GRIN-Global database. The ARS curator in Pullman, Washington, will assist with assembling the panel and providing seed for our research. Since the quantity for many of the varieties is very limited we will use locations as replications in a Randomized Complete Block Design with a plot size of 1 meter by 4.6 meters. This design will fulfill our objectives without confounding statistical constraints. All alfalfa collections plus five controls (“Vernal” – to correct harvest timing in a day as covariate) will be seeded in spring of 2018 at each location. We will follow best management practices (BMPs) to fertilize and control pests. Alfalfa plots will be harvested at each location at 10% bloom by cutting a 1-m swath at a 5-cm stubble height through the center of each plot with a sickle-bar (Idaho) or flail-type harvester (Washington and Oregon). A 500 to 600 g subsample will be taken from each harvest, weighed in the field immediately, dried at 60° C to approximately 90% DM and ground through a 2 mm screen in a Wiley mill. First-cut samples (only) will then be sent to Rock River Labs, Inc (Watertown, Wisconsin) for determination of NDF, NDFD24, NDFD30, NDFD48 and iNDF by NIR. Rate of NDF digestion (kd), potentially digestible NDF (pdNDF) and Total Tract NDF Digestibility (TTNDFD) will be determined according to the fiber digestion model described by Lopes, et al. (2015a). Efforts to determine alfalfa forage quality will be done. Depending on each location, we will pursue further cuttings to monitor seasonal alfalfa yield. Fall dormancy, pest resistance, and mean growth stage by count and height at harvest will be rated and monitored accordingly. Immediately prior to the first cutting, alfalfa forage samples will be collected by the USDA, Agricultural Research Service (ARS) Primary Investigator (PI). A co-PI in Washington will coordinate field- and laboratory efforts in Washington. A co-PI in Oregon will coordinate field research in Oregon, and another co-PI will coordinate field research in Idaho.