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Induction of chlorophyll mutations in bread wheat A. H. KHAN Nuclear Institute for Agriculture and Biology, Lyallpur, Pakistan Triticum vulgare variety Mexi-Pak (2n=42) was used in this study. Chlorophyll mutations occur very rarely in hexaploid wheat spontaneously but are induced frequently by chemical and radiation mutagens. Most of them are Mendelian recessive. Seeds were soaked in deionized water for two hours and then treated with 0.5, 1.0, 1.5 and 2.0 per cent EMS for 6 hours. After the treatment, seeds were washed thoroughly in running water and dried before sowing. Dry seed with 12 per cent moisture content were irradiated with gamma-rays for 10, 15, 20 and 25 KR by Co60 source of this Institute ; and neutrons irradiation of 300, 400, 500 and 600 RAD was carried out by IAEA Laboratories, Vienna. Seed germination and fertility was noted in M1 and chlorophyll mutations were recorded in M2 population. 20 seed per spike and 3 spike per M1 plant sown for M2 screening. The frequency of chlorophyll mutations in Mexi-Pak in M2 following treatment with various mutagens is shown in the Table 1. The data do not suggest any relationship with the type of mutagen or the dose. The seed fertility of M1 plants whose progenies segregated for chlorophyll mutations is also indicated in the Table 1. There is no relation between the seed fertility in M1 and the occurrence of chlorophyll mutations in M2. Although no record was made but the frequency of striata and albino chlorophyll mutants was more in the irradiated material when most of the xantha and viridis mutants were produced in EMS-treatments. (Received April 30,1971) |