A REVISED PROTOCOL FOR EFFICIENT REGENERATION OF SOMATIC EMBRYOS AND ACCLIMATIZATION OF PLANTLETS IN PECAN, CARYA-ILLINOENSIS

Methods were established to increase the frequency of plant regenerati on and greenhouse establishment of pecan somatic embryos. Somatic embr yos were derived from immature zygotic embryo explants maintained on b asal woody plant medium (WPM). The isolation and culture of 3-4-mm lon g somatic embryos on fresh medium promoted enlargement and increased t he number of uniformly sized somatic embryos for cold and desiccation treatments. Incorporation of silver nitrate, an ethylene biosynthesis inhibitor, in WPM germination medium and application of 6-benzylaminop urine on shoot apices appreciably increased shoot regeneration frequen cy. Wide variations in plant conversion rates were observed among diff erent culture lines. Nonetheless, the overall frequency of plantlet co nversion averaged 20%, up to a maximum of 71%. The regenerated plants were grown in perlite:vermiculite followed by stepwise hardening. From 70 to 80% of the regenerated plants reached the hardening stage; >990 /. of the hardened plants were successfully established in the greenho use.