Embryo culture techniques are employed in early ripening peach and nectarine [Prunus persica (L.) Batsch] cultivars. Generally the embryos in these varieties are not mature by the time the fruit matures, thus rendering normal stratification procedures ineffective. In 1998 and 1999, immature embryos from multiple peach genotypes were cultured in an embryo rescue medium (WPM, 3% sucrose, 0.065% agar) at 5 degreesC for 45 days in the dark. Embryos were then placed under lights at either a cool temperature (18 degreesC in 1999 and 20 degreesC in 1998) or a warm temperature (30 degreesC in 1999 and 28 degreesC in 1998) treatment with a photoperiod of 12 hours for germination and initial growth. After 2-4 weeks embryos were rated for germination, root number, and top growth. The embryos incubated at the cool temperature regime not only had better germination, but also had a higher rate of greenhouse survival.
