REGENERATION OF PEACH [PRUNUS-PERSICA (L) BATSCH] ROOTSTOCK CULTIVARS FROM COTYLEDONS OF MATURE STORED SEED

Shoots were regenerated from cotyledons of mature stored seed of three peach rootstock cultivars ('Flordaguard', 'Nemared', and 'Medaguard'). Shoot regeneration rates were highest when cotyledons were cultured for 3 weeks in darkness on Murashige and Skoog (MS) medium with 2.5% sucrose and a combination of IBA (1.25 or 2.5 mu M) and TDZ (6.25 or 12.5 mu M). Regeneration rates for 'Flordaguard', 'Nemared',and 'Nemaguard' were as high as 60%, 33%, and 6%, respectively, Length of seed storage (1 to 3 years) did not affect regeneration rates. Seventy percent of regenerated shoots produced rooted plants, This regeneration method is rapid and simple, and stored seed can be used year-round, It may be a useful regeneration system for gene transfer in seed-propagated peach rootstocks. Chemical names used: 5 indole-3-butyric acid (IBA); thidiazuron (TDZ).