Alfalfa is one of the most important forage crops for the Canadian beef and dairy industries. In the Canadian Prairies alone, there is over 4.5 million hectares of pure alfalfa or grass-alfalfa mixed stand in production. Development of regionally adapted new alfalfa cultivars has been an important topic for various industry groups. This research project is an important first-step toward initiating an active alfalfa breeding program in Saskatchewan. We have collected and developed a set of alfalfa germplasm for the future alfalfa breeding. Besides this, 13 new alfalfa synthetic lines have been developed through this project using plants from 14 long-term grazing sites across four soil zone of Saskatchewan and new alfalfa germplasm introduction. The 13 alfalfa synthetic lines can be grouped to 1) high yielding alfalfa line with reduced fall dormancy 2) yellow flowering alfalfa lines with drought tolerance 3) grazing tolerant alfalfa line 4) extreme winter hardy alfalfa line.

Among the 14 alfalfa populations with long-term grazing history, the populations from Black soil zone had the highest vigor and forage yield among the soil zones in this study. The regrowth yield was similar for the populations from Grey and Black soil zones, which was higher than the populations sampled from the Brown and Dark Brown soil zones. The majority of alfalfa genotypes sampled from the long-term grazing sites contained both falcata type (yellow flower) and Sativa type (purple flower) genetics, but the sativa background dominated in the populations. There was a trend of genetic shift of the populations among the soil zones. The populations from Black and Brown soil zones had a tendency to shift toward two different directions while the populations from Dark Brown and Grey-wooded zones were intermediate overlapping with others. This clearly demonstrated a long-term adaptation to local growth environment. This study also identified five major SNP markers for tillers number, fall dormancy and regrowth traits of alfalfa.

In this study, forage yield data of alfalfa cultivars tested from 1997 to 2011 in the Western Forage Variety Testing System were analyzed to understand forage yield trend of alfalfa in the prairies. We found there was no significant trend of alfalfa yield increase in western Canada in the past 15 years. However, regrowth yield of alfalfa cultivars released from 2000 to 2011 showed an increase under irrigation. We concluded that development of alfalfa cultivars with tolerance to early season drought would be necessary to stabilize alfalfa production under changing climate in the Canadian prairie.

This project also provided research experience opportunities to many undergraduate students, trained a 6-credit undergraduate thesis student, and a Ph. D student in alfalfa breeding and genomics at the University of Saskatchewan.

Key Messages:

• This research project has initiated an active alfalfa breeding program in Saskatchewan, and developed 13 new alfalfa synthetic lines adapted to Canadian prairie regions.
• There was a trend of genetic shift of the alfalfa populations following a long-term grazing with the populations from Black and Brown soil zones had a tendency to shift toward two different directions while the populations from Dark Brown and Grey-wooded zones were intermediate to them.
• This study also identified a few major molecular markers for alfalfa selection in the breeding program.
  Development of alfalfa cultivars with tolerance to early season drought would be necessary to stabilize alfalfa production under changing climate in the Canadian prairie.
• Trained a Ph.D student in alfalfa breeding and genomics.