| Cytogenetical effects of radiation on the stability
of triticale MIR MOHAMMAD RAJPUR*, ABDUL JABBAR MALIK* and MARIE BRAGDO-AAS** * Department of Plant Breeding & Genetics, Sind Agriculture University Tandojam, Pakistan. and ** Agriculture University of Norway, Aas. Ionizing radiations have been found effective in inducing a series of chromosomal alterations of diverse forms, creating greater variability than would result from chemical mutagens. Chromosome anomalies such as deletions, duplications, translocations, laggards, fragments and bridges have been frequently observed in irradiated populations of several crop plants (LARIK 1978; LARIK & THOMAS 1979). Extensive investigations on the effect of physical and chemical mutagens on the cytological behaviour of wheat and other crop plants have already been reported. An attempt has been made in the present work to extend these studies. This paper presents an analysis of meiotic anomalies in MI populations of three crop species and discusses their significance with reference to genetics and plant breeding. Materials and Methods Seed samples of three species, Viz. wheat (Local), triticale (Beagle), and rye (var, II). were exposed to doses of 1.5KR and 6KR of X-ray, and sown in pot house for cytological investigations. Young spikes were fixed in a fresh mixture of alcohol and glacial acetic acid "Cornoy" (3:1) and replaced by 70% alcohol after 24 hours. The material was stored at -4C and stained in orceinacetic acid (DARLINGTON & LACOUR 1976). The meiotic observations were made on sqash preparations of pollen mother cells and recorded in terms of chiasmata, univalents and multivalents, bridges, bridge + fragment and micronuclei. All cells, which could be analysed, were registered. As far as possible diakinesis, metaphase I, anaphase-I and II, telophase and tetrad stages were investigated. Five plants from each treatment and 30 cells per plant were examined. |
| --> Next |