THE ASSESSMENT OF INVITRO CHARACTERS AND THEIR INFLUENCE ON THE SUCCESS RATES OF DOUBLED HAPLOID PRODUCTION IN BARLEY

An assessment of in vitro characters: embryo size, differentiation stage and germination time of haploid embryos, was carried out with a view to developing a selection procedure to increase the efficiency of doubled haploid (DH) production using the Hordeum bulbosum system. The differentiation stage of haploid embryos at the time of excision was found to be the most promising character for selection. In the two spring crosses examined 55% of excised embryos were undifferentiated and 45% were differentiated, with overall success rates, in terms of the percentage of DHs produced, of 7.91% and 25.16%, respectively. 17% of excised embryos produced callus. These embryos performed poorly in terms of regeneration and subsequent growth. It is suggested that only differentiated non-callusing embryos are maintained in order to maximize the efficiency of DH production. It is also shown that the overall success rate depends not only on initial stages such as seed setting but also on genotypic differences in response to colchicine treatment at later stages.