COMPARISON OF CALLUS-CULTURE WITH EMBRYO CULTURE AT DIFFERENT TIMES OF EMBRYO RESCUE FOR PRIMARY TRITICALE PRODUCTION

Callus culture of immature wheat-rye hybrid embryos was compared with embryo culture in two experiments. Embryos were rescued from field gro wn mother plants at two day intervals 13-21 days after pollination and plated for 1) callus culture on Murashige and Skoog medium (MS) suppl emented with 2 mg/l 2,4-dichlorophenoxy acetic acid followed by plant regeneration on hormone free MS medium with half strength mineral salt s, 2) embryo culture on Taira and Larter medium (TL). Observations wer e made on embryo size and condition at time of rescue (Experiment 1) a nd embryo development directly into plants (embryo culture) or through embryogenesis (callus culture). Fewer 19 and 21 day old embryos devel oped into plants from callus culture than from embryo culture in Exper iment 1. Callus culture was more efficient than embryo culture in prom oting plant recovery from 17 day old embryos in Experiment 2. The numb er of plants per embryo was significantly higher from callus culture t han from embryo culture. In both experiments callus culture promoted e mbryogenesis in more embryos than developed in embryo culture. Embryo rescue 15-17 days after pollination was optimal in both experiments.