SOMATIC EMBRYOGENESIS AND PLANT-REGENERATION FROM BARLEY CULTIVARS GROWN IN SPAIN

Thirty-two barley cultivars grown in Spain, 18 of the two-row type and 14 of the six-row type, were screened for plant regeneration from cul tured immature embryos. Although there was much variation in regenerat ion capacity among the cultivars, plants were obtained from all cultiv ars except Almunia. No statistical differences were found in the perce ntage of regeneration between two- and six-row types. The influence of the auxins 2,4-dichlorophenoxyacetic acid, dicamba, and picloram on t he induction and maintenance of embryogenesis and regeneration capacit y after 3-4 months in culture, were evaluated for cultivars Cobra, Hop and Reinette. Hop had the highest rates of maintenance of embryogenic capacity and plant regeneration. The medium containing dicamba gave t he best embryogenic callus induction, maintenance and regeneration. Fi ve regeneration media, differing in growth regulators and micronutrien t composition, as well as partial desiccation of the calli before rege neration, were tested. The regeneration medium containing 10 mu M copp er sulfate gave the best results. Regeneration frequencies after 3-4 m onths in culture of cultivar Hop were raised from 59.5 to 93.7% in thi s medium. Silver nitrate and partial desiccation of the calli also enh anced giant regeneration, but the medium containing 10 mu M of silver nitrate reduced root formation.