Effects of chronic gamma irradiation in Durum and bread wheats

Abstract

Plants of different varieties of durum and bread wheats were subjected to several dose rates of chronic gamma irradiation for the whole of their life cycle or allowed to recover after 38 or 56 days of irradiation. In plants subjected to daily exposures of 148 and 72 r with or without a recovery period, the following growth reactions were observed: (1) increase in the mean number of culms per plant and (2) increase in the mean weight per mature plant. In both durum and bread wheats the strongest tillering reaction was typical of the late varieties. Analysis of the number of spikes per plant showed that three out of the ten varieties tested formed spikes in greater number than the controls at 148 r/day chronic exposure; an increase in mean number of spikes per plant was observed in most of the varieties at 52 and 72 r/day. Spikelet fertility and germinability of seeds produced by irradiated plants showed that the group of bread wheat varieties, as a whole, is more radiation resistant than the group of durum wheat varieties. Among these, Aziziah appeared the most radiation sensitive, and Cappelli the most radioresistant.