Accelerated aging tests with seeds of 11 flax (Linum usitatissimum) cultivars

Seeds of 11 flax (Linum usitatissimum) cultivars from North American and European breeding programs were used for accelerated aging tests conducted at high relative air humidity, at 42 degrees C, for 48 hours and 72 hours using the inner chamber method. Depending on the cultivars, the germination reduction ranged from 0 to 72.8% after 48 hours and from 61.5 to 100% after 72 hours of accelerated aging. The accelerated aging test for 48 hours allowed for better differentiation among the cultivars than the 72 hour test. In both tests, the brown-seeded fibre flax 'Nike' showed the lowest and the yellow-seeded linseed cultivar 'Minerva' the highest germination reductions. The highest germination reductions were found in cultivars with yellow or olive seed colour and the lowest reductions in cultivars with brown seed colour. In the medium range of germination reduction, some yellow-seeded cultivars showed less germination reduction than brown-seeded cultivars, which indicates that selection of yellow-seeded flax with stable seed vigour is possible. The 1000-seed weight of the cultivars was not correlated with germination reduction. Germination reduction was negatively correlated (r = -0.66 and r = -0.65) with initial germination rates. The average seed moisture content increased during accelerated aging from the initial 6.3% to 25.9% after 48 hours and 37.1% after 72 hours. Cultivar differences in seed hygroscopicity may have influenced germination reduction, because there was a tendency of higher seed moisture contents after accelerated aging to be associated with higher germination reduction (r = 0.60 and r = 0.46).