The relationship of the efficiency of energy conversion into growth as an indicator for the determination of the optimal dose for mutation breeding with the appearance of chromosomal abnormalities and incomplete mitosis after gamma irradiation of kernels of Triticum turgidum ssp. durum L.

Abstract

The study aim was to determine the optimal gamma irradiation dose for mutation breeding in Triticum turgidum ssp. durum L. Root, shoot and seedling growth, as well as the efficiency of energy conversion into growth were determined to examine the growth retardation effects of gamma irradiation that are the result of DNA damage (bridges, ring chromosomes, micronuclei, incomplete mitosis) in Triticum turgidum ssp. durum L. The kernels were irradiated with doses of 50, 150, 250 and 350 Gy using a ⁶⁰Cobalt gamma-ray source. The kernels were placed in germination paper at 25 °C to grow for a 132 h period for the determination of shoot and root growth and the efficiency of energy conversion into growth. Root tips were collected and fixated over a 47.5 h growth period for the determination of the chromosomal abnormalities and incomplete mitosis. The control differed highly significantly (p < 0.01) from irradiated samples at all doses in root growth and from 250 to 350 Gy samples in shoot growth and the efficiency of energy conversion into growth. There was a highly significant (p < 0.01) increase in the number of bridges and micronuclei between 50 Gy samples and samples irradiated with the higher irradiation doses while 50 Gy samples differed only from 250 and 350 Gy samples regarding ring chromosomes and interphase cells with incomplete mitosis. Root and seedling growth on the one hand and the efficiency of energy conversion into growth on the other were found to be measuring different effects of gamma irradiation on plant growth. The latter was used for the determination of the optimal dose for mutation breeding as 155.52 Gy.