Leveraging genetic resource diversity and identification of trait-enriched superior genotypes for accelerated improvement in linseed (Linum usitatissimum L.)

Linseed or flaxseed, native to the Indian subcontinent, had undergone domestication, edaphic selection and evolutionary processes that may have resulted in huge genetic variability in Indian genotypes. To understand the hitherto unexplored genetic diversity for sustainable flaxseed production amid challenges of climate fluctuation and identify trait-specific high-yielding genotypes, 2576 unique linseed accessions were comprehensively evaluated for 36 traits for up to six environments representing two major agroecological zones in India. A wide range of variability was recorded for days to initiation of flowering (42.86-114.99), plant height (43.31-122.88 cm), capsules/plant (64.62-375.87), seed size (6.06-14.44 cm²), thousand seed weight (2.80-11.86 g), seed yield (2.93-17.28 g/plant), oil content (30.14-45.96%) and fatty acid profile especially the key constituent omega-3 fatty acid (25.4-65.88%). Most of the traits such as plant height, flowering time, seed yield, seed and capsule size showed a high or moderately high level of variance coupled with high broad sense heritability indicating precise capturing of less heritable quantitative traits. The infraspecific classification of the tested collection revealed the seed/oil type (2498 accessions) as the dominant morphotype over dual-purpose/fiber flax (78 accessions) in the conserved collection. Correlation analysis indicated a significant positive association between flowering time, plant height, days to maturity and oil content. Trait-specific superior genotypes for earliness (50% flowering in < 60 days, maturity in < 122 days), bold seeds with high thousand seed weight (> 11 g), capsules/plant (> 350), oil content (> 45%) and fatty acid composition (> 65% alpha-linolenic acid) were identified to aid genetic improvement of linseed and to broaden the narrow genetic base.