| Radiation experiments on Triticum durum and
Triticum vulgare R. E. SCOSSIROLI Institute of Genetics, University of Pavia, Italy Polygenic systems controlling quantitative characters have been shown to undergo spontaneous as well as X-ray induced mutation. In view of the significance of such findings for problems of evolution, as well as for plant and animal breeding, an experiment has been started for obtaining more data on the induction of mutations in polygenic systems by treatments applied to seed, using T. durum (one variety: Cappelli) and T. vulgare (two varieties: Damiano and Mara). At present, data on the effect of X-ray treatment at a dose of 10,000 r applied to seed and observed on R1 plants are available. Treatments (230 Kv, 1-2 mA, 4 mm Al filter) were given to part of the seed of several heads; the remaining seed being used as control. Each head had been considered as the parent of lines for which treated and untreated progenies were available. On the seedlings the length of the coleoptile and of the main root at 3 and 5 days of age have been found to be reduced by the treatment. Interactions Head x Treatment were found to be significant for these traits. Such finding shows a different response of different heads to the same treatment. On the mature plant the number of internodes was reduced and the internodes were shorter, so that the plant height was found to be reduced in the series when compared with the control. Interactions Head x Treatments were found to be significant for such traits. On the ears a reduction of the internode length was observed in T. vulgare and a reduction of the number of spikelets and of the number of seed set was found in T. durum and T. vulgare. This work will be continued in order to obtain data on variability for different polygenic traits in the treated as well as in the untreated series. |