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Breeding Methods

Flax plots nearing harvestThe primary objective is to develop and evaluate genetic material to improve yield potential while maintaining resistance to pests, maintaining oil content and oil quality and maintaining other agronomic characteristics for potential cultivars. Since producers have historically planted later than would be expected to produce greatest yields, a part of the breeding effort will be devoted to evaluation at a delayed seeding date.  With the interest in flax as a human food, a minor effort will continue to evaluate material with a yellow seed coat color which is preferred for “eye appeal”.

Goals are to develop flax cultivars with desirable agronomic characteristics; seed yielding ability; quantity and quality of oil; tolerance to wilt and pasmo; and resistance to known North American races of rust.  The breeding program will be divided into two major parts: 1) rust resistance for two genes conditioning resistance (M3 P3), and 2) use of other genes for resistance (either as one gene or multiple). The two parts would require different groups of crosses.

In addition, a minor effort will be to continue to evaluate golden (yellow-seeded) flax as preferred in the human food market.  Most of the breeding program will follow a pedigree breeding scheme (Kenaschuk, 1975).  The details of the planned breeding methods to be used are as follows:

  • Cross and F1 generation:
    Crosses between selected parents will be made in the greenhouse and the F1 plants grown in a greenhouse.
  • F2 generation:
    From 500 to 3000 F2 plants will be grown the following year in the greenhouse and evaluated for rust resistance.
    Resistant plants will be grown to maturity.
  • F3 generation:
    Progenies of rust resistant F2 plants will be grown in the field and selection will be made on agronomic appearance for the best plants within the best family. Normally, four plants will be selected from each selected family.
  • F4 generation:
    Plants will be evaluated for rust resistance in the greenhouse and only lines homozygous for resistance will be planted in the field the following year.  Four to six plants will be selected from selected families.
  • F5 generation:
    Seed from selected F4 plants will be planted as hills.  Selected hills will be advanced.
  • F6 generation:
    Lines will be grown in field trials for yield evaluation. In addition, data will be collected on other characters such as flowering date, plant height, wilt tolerance, etc.
  • In later generations, yield testing will be conducted at multiple locations on selected lines.  The most promising lines will be evaluated in "tri-state" trials.  All lines in the "tri-state" nurseries will be evaluated for oil percentage, iodine value, height, maturity, lodging, pasmo as well as yield in both early and late seeded nurseries.  Presently, the "tri-state" nurseries are grown in ND, SD, and Manitoba, Canada.  Each cooperating station grows two trials per season.  Selected lines from "tri-state" nurseries are grown in regional trials in the flax growing area.  As a final stage of evaluation, lines will be evaluated in Research Extension Center trials and increased, named and released. Selected material of high priority will be rapidly advanced in a modified single seed descent method to "pure" lines for yield evaluation.

Population improvement

The secondary objective to develop and maintain populations with useful genetic variability is necessary to support the development of improved cultivars. Much of this effort will center on the health food aspect of flax.  Yellow seed coat is preferred in the human food products.  In addition, concern has been expressed concerning the level of Cd in the seed of several plants including flax.

Several potential sources of yellow seed color have been identified in the U.S. collection of flax (Miller et al., 1982).  Several lines have been selected for crossing with low accumulating Cd lines (additional breeding is planned after evaluation of Cd content in the crossed material).  In addition, crosses have been initiated with selected advanced yellow seeded experimental lines and adapted brown seeded lines. The segregation of advancing generations will be followed to determine mode of inheritance of yellow seed coat color and potential as varieties for the health food market.  As the material is developed it may be important to evaluate other quality characteristics for health benefits (lignan content, etc).  Populations need to be available in the event a market change can be captured.  Diverse populations will be maintained to attempt to meet changes in demand.

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