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The most commonly used measurement of radiation damage to seeds is seedling height, the mean height a lot of seeds attains at some time during exponential growth. If planted immediately post-irradiation, seeds of a dose lot give a normal height distribution, but if stored before planting give very abnormal and even bimodal height distributions. By within-seed comparisons of chromosome abnormality (from roots excised at 24-36 hr) with height (attained by 7-9 days) in irradiated barley seeds, it is shown that damage to height and to chromosomes are closely correlated, even within a treatment in which great heterogeneity occurs. The two effects have equal radiosensitivity, but different shoulders to their dose curves. Seedling height is not depressed until 25-30 per cent of the cells bear chromosomal abnormalities. The heterogeneity observed is not due to a between-seed heterogeneity in dose or in oxygen content, and probably not in moisture. These experiments show that the heterogeneity arises from factors that operate on post-irradiation (indirect) storage damage, but are without effect on during-irradiation damage (direct). © 1969 Pergamon Press Ltd.

21 citations (Crossref) [2023-10-31] Citation Key Alias: lens.org/005-909-794-378-407 tex.type: [object Object]