| I. Research Notes A liguleless mutation radioinduced in Triticum durum DESF. D. BAGNARA and L. ROSSI Laboratory for the Applications of Nuclear Energy in Agriculture, National Committee for Nuclear Energy, Rome, Italy Mutagenic treatments of dry seeds of Triticum durum cv. Capeiti and Ga B 125 (the latter being itself a radioinduced short straw mutant from the cultivar Garigliano) were made in 1967 in our Laboratory. Mutagens and doses applied are detailed in Table 1. Treated M1 seeds were space planted and the main spike of each M1 plant was bagged in order to prevent open pollination. M2 generation was grown as M1 spike progeny in spaced conditions. Both Capeiti and Ga B 125 treated materials segregated in M2 generation a mutation ("liguleless") for which "auricolae" are completely absent and "ligula" is strongly reduced. The leaf habit is consequently affected, being more erect not only in respect to mother variety but also to all other durum types. Studies in cereal crops have shown the higher efficiency in light utilization of erect leaves in respect to horizontal ones (MONSI and SAEKI 1953, SAEKI 1960). The positive correlation between erect leaves and a higher crop yield has also been proven in barley and wheat (TANNER et al. 1966) as well as in other cereals. The agronomic behaviour of the species is therefore presumably affected by the liguleless mutation. In Capeiti, 2193 M2 progenies were screened, out of which only one, from the treatment with fast neutrons at the dose of 700 reps, segregated the mutation. Segregation ratios in M2 and M3 and chi square of fitness under the hypothesis of monogenic inheritance and full dominance are given in Table 2: A slight deficit of liguleless individuals occurs in M2 generation, presumably due to the chimeric structure of M1 spike. As for other characters which can be of agronomic importance, a comparison is set in Table 3 between mother variety and mutant, grown in the same field environment. It is still to be ascertained whether the shorter culm and lower kernel weight exhibited by the mutant are due to side effects of the liguleless factor or to other modifications of the genetic background. In Ca B 125, 1471 M1 spike progenies were analyzed, and three of them were found to segregate liguleless plants. For each of them, Table 4 gives data about segregation ratios in M2 and M3 generations, under the hypothesis of monogenic inheritance and full dominance. Departures from expected ratios seem to occur in M2 and M3 segregations observed in G 1008 M2 progeny. Data concerning other characters are given in Table 5 for each mutant progeny obtained from Ga B 125. Mutant lines coming from both Capeiti and Ga B 125 are now being crossed each other with the purpose of checking whether the mutation has the same genetic basis. Transfer of the mutation itself to other genotypes for breeding purposes, as well as the agronomic evaluation of mutant lines, is also underway. Literature cited MONSI, M. and T. SAEKI 1953. Jap. J. Bot. 14: 22-52 SAEKI, T. 1960. Bot. Mag. Tokio 73: 55-63. TANNER, J. W., C. J. GARDENER, N. C. STOSKOPF and E. REINBERGS 1966. Can. J. Pl. Sci. 46: 690. (Received September 12, 1971) |
| Contribution No. 303 from the Laboratorio per le Applicazioni in Agricoltura del C.N.E.N., Centro Studi Nucleari della Casaccia, S. Maria di Galeri, Rome, Italy. |