Phenotypic Mutations Induced During Storage in Barley and Pea Seeds

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Abstract
Previous work on chlorophyll-deficiency mutations in pea and barley has shown that a significant increase in mutations is induced by storing seeds under various conditions which lead to losses of viability to about 50 per cent. The work here shows that a detectable increase in mutation frequency is also associated with much smaller losses of viability. Pea seeds were stored at 35 °C and 16.5 per cent moisture content for 40 and 57 d when viability fell from 99 to 93 and 82 per cent, respectively. At the same time mutation frequency (percentage of seeds containing recessive point mutations) increased from 1.62 per cent in the control treatment to about 3 to 4 per cent. Barley seeds at 15.5 per cent moisture content were stored at 50 °C for 42 and 54 h, and at 35 °C for 28 and 39 d. During these ageing treatments viability fell from 98 to 75, 26, 93 and 48 per cent respectively and the mutation frequency increased from zero to between about 0.3 to 0.9 per cent. In both species the induction of mutation by ageing treatments was significant but the differences between the various ageing treatments were not. It is concluded that there is probably no safe threshold loss of viability which completely avoids mutation, and these results support the view that for genetic conservation seeds should be stored under conditions which minimise loss of viability.