The effect of seed colour and linolenic acid concentration on germination, seed vigour, seed quality and agronomic characteristics of flax
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The world market for edible vegetable oils is large and expanding. Edible-oil cultivars of flax (Linum usitatissimum L.) have potential to benefit the agricultural industry. A mutation program at the University of Saskatchewan resulted in a flaxseed oil with a very low linolenic acid concentration (2%), compared to the regular industrial flaxseed oil (50%). To register edible-oil flax ("solin") cultivars in Canada, they must have a linolenic acid concentration of less than 5%, and yellow seed in order to be visually distinguished from brown-seeded industrial oil cultivars. Incorporation of low linolenic acid and yellow seed colour into flaxseed may negatively impact seed germination, seed vigour, emergence, seed quality and agronomic characteristics. This study investigated the effect of seed colour and linolenic acid concentration on these characteristics. The effect of temperature, soil and seed damage on germination were also investigated. Near-isogenic flax populations of yellow and brown seeds with high and low linolenic acid produced from seven crosses were used. A temperature of 5°C resulted in significantly lower germination than temperatures of 10 or 15°C. In general, germination was not affected by seed colour and linolenic acid level. A cold test used to measure seed vigour showed that yellow seeds have significantly lower vigour than brown seeds. The same result was obtained with a germination test in soil and in field emergence. Low linolenic acid seeds had significantly lower seed vigour in two populations, lower germination in soil, and in 1995 a lower field emergence than high linolenic acid seeds. The significant negative effect of soil in the cold test, as well as the positive effect of soil autoclaving on germination indirectly suggested that soil microorganims deleteriously affect germination, particularly for yellow seeds. Also, the cold test was able to differentiate the seed vigour for seed colour and linolenic acid level and was in agreement with field emergence. The cold test can be a useful, rapid method for predicting field emergence of solin breeding lines. Mechanical harvesting had a significant effect on seed damage but, not on seed vigour. Yellow-seeded lines had lower seed yield, greater oil concentration and more seed coat damage than brown-seeded lines. In general, maturity, visibly damaged seed and seed weight was not affected by seed colour. Linolenic acid concentration had no significant effect on these characters except seed yield. Low linolenic acid lines had greater seed yield in 1995.