Breeding and Development of Perennial Sunflower and Perennial Flax Varieties for Low-Input Agriculture

Breeding and Development of Perennial Sunflower and Perennial Flax Varieties for Low-Input Agriculture

Summary

This project is part of a long-term program that will bring perennial sunflower and perennial flax into agricultural systems to allow farmers to diversify their operations, improve profits, improve environmental quality, and reduce inputs of labor and supplies. In the last year and a half, we developed perennial flax breeding populations that will be evaluated in several organic and conventional field sites in Minnesota and North Dakota this year. A major breakthrough was achieved in our perennial sunflower populations, in which we retained perennial habit after back crossing with an elite annual inbred, an accomplishment never before recorded.

Objectives/Performance Targets

Objectives of current research:
1. To produce and improve interspecific populations of sunflower to begin the process of moving the perennial habit genes from H. tuberosus into the crop-type annual genome of H. annuus.
2. To begin the process of improving the perennial species of flax (Linum spp.) for agronomic characteristics using recurrent selection.

Short term outcomes:
1. Determine the inheritance of perennial habit in annual x perennial sunflower populations while developing additional populations, as needed.
2. Develop perennial flax populations for line evaluation at multiple locations.

Intermediate term outcomes:
1. Develop perennial sunflower inbred lines.
2. Develop perennial flax open-pollinated varieties (OPVs).

Accomplishments/Milestones

Listed by Short term Outcome:
1. Determine the inheritance of perennial habit in annual x perennial sunflower populations while developing additional populations, as needed. The F¬1 plants with the French (annual) cytoplasm and H. tuberosus (perennial) cytoplasm were observed during the summer of 2006 and survival was determined after the winter of 2006-2007. Nearly 100% of the F1 plants produced tubers in the field and survived winter successfully, indicating that there was no maternal or cytoplasmic effects on perennial habit. Further, the formation and behavior of the perennial organs were similar to the perennial parent, indicating the perennial habit is due to a dominant, gain-of-function set of genes. Crosses with the perennial parent produced more progeny; however, this was expected because the parent with the higher ploidy level generally produces more seed in interspecific crosses. The BC1F1(4x) populations produced in 2006 included about 1000 plants, which is nearly a ten-fold increase in population size over typical triploid BC1F1 populations. Of these 1000 plants, 8 plants were perennial as determined by regrowth after the winter of 2006-2007. These plants will be maintained for further study in our permanent collection. Some plants in the population did not survive in the field, but appeared to produce rhizome-like sprouts. These plants may have had some, but not all, of the genes necessary to be a successful perennial in our environment. (H. tuberosus, the donor of perennial habit, is a Minnesota native plant, and is extremely winter hardy in our environment.) It appears from the infrequency of perennial progeny that there are several important perennial habit genes. The data also suggest it will be possible to carry these genes through successive backcrosses if care is taken to maintain an adequate population size. These results will be published this year in the Proceedings of the 17th International Sunflower Conference, Cordoba, Spain. We believe that we have reached our short term objectives of obtaining information on the inheritance of perennial habit, producing new breeding populations, and publishing our findings. We have exceeded our own expectations by making a breakthrough: production of a BC1F1 population with fully perennial individuals.

2. Develop perennial flax populations for line evaluation at multiple locations. During the course of this SARE project, we have been able to improve the seed germination and vigor of the seedlings using a recurrent selection approach, in which only the plants with good vigor and fast germination were selected from the populations and random mated. Ideally, we would have evaluated these factors together with yield and agronomic traits, but the seedling vigor and seed dormancy factors would have affected the observations on yield and agronomic traits, rendering the data sketchy at best. By selecting for seedling vigor and fast germination first, we obtained two populations that had better germination and still maintained a great deal of the initial genetic variation of the population. This is what we would expect according to breeding theory. Genes at locations distant to the genes responsible for seed dormancy and seedling vigor factors are largely unaffected by selection for seed dormancy and seedling vigor. Thus, we can improve one very important characteristic first, and focus on agronomic and yield characteristics second without the confounding nature of seedling vigor differences among the lines. We will begin the first screening for agronomic and yield factors starting this spring. Lines were derived by harvesting seed from individual plants that survived the winter of 2006-2007. These lines are called half-sib lines, because the female parent is a single plant, but the male parents are all of the other plants in the population. By planting these lines out in the field in a randomized, complete block design at multiple environments, we can determine the total contribution of genetics to total field variation. Further, we will obtain information on which plants have the best genetics. We can then random mate the best plants to produce populations with better characteristics. We believe that we have reached our short term objectives by generating populations with improved seedling vigor and less seed dormancy than previous populations. The lines selected for agronomic evaluation starting this year (2008) were produced exclusively from plants that were able to survive the winter of 2006-2007; therefore, the lines are expected to have improved winter hardiness over most of the parent lines.

Impacts and Contributions/Outcomes

The data produced from this project and the preliminary work done before this project have been instrumental in learning about the inheritance of perennial habit in sunflower and developing breeding strategies for perennialized crop-type sunflower. Some of the F1 sunflower populations are also being studied for potential as a feedstock for cellulosic ethanol production. Further, we have determined that there is variation for seedling emergence, vigor, and some agronomic traits in perennial flax populations. We will add to this knowledge with field evaluations being conducted in 2008 and in future years.

Because this project is of a longer term nature than most SARE projects, it is hard to determine at this time what the economic impacts will be. If these crops are successfully perennialized, the potential is there for the perennial versions of these crops to replace the annual versions on the rural landscape. Consistently high demand for the value-added products of these crops over the last several years, combined with the potential for enhanced erosion control and nutrient scavenging, could make perennial sunflower and flax more desirable than the annual versions of the crops. One reason that sunflower is avoided by producers today is because it is a relatively high-maintenance crop. A perennial version would require less maintenance. Short term, the impact is largely scientific, although the work is drawing interest from many producers who ask for tours of our plots. Over the longer term, as perennial varieties are released, the impact could include changes in crop rotation and other production practices. These crops will also have conservation value.

Collaborators: