311 Seed Treatments, Rootstock Cultivar, and Environment Affect Peach Seed Germination

Abstract

Poor peach seed germination can be a problem for commercial tree fruit nurseries. Even standard rootstocks such as Lovell and Nemaguard do not always have high germination rates. New seed-propagated rootstocks under development, such as Guardian peach rootstock, often are selected for their field traits, with nursery characteristics being of secondary importance. Guardian rootstock is derived from bulked open-pollinated seed from a number of F1 seedling selections. Germination of Guardian bulked seed has been poor. Four pre-stratification cold treatments were given to four 100-seed lots each of Lovell, Nemaguard, and 10 Guardian selections prior to planting each year (1994 to 1998) in a Cecil sandy loam at Musser Fruit Research Center near Clemson, S.C. Treatments included taking dry, refrigerated seed that were harvested in August and soaking 100-seed seedlots in 1500 mL perlite and 400 mL distilled water for 0 (no soaking), 2, 4, 6, and 8 weeks at 6 °C before sowing (typically early November). All treatments consisted of 25 seeds per replicate (4 reps/year) per rootstock or selection and were sowed the same day. The experiment was analyzed as a blocked split plot design with duration of stratification the whole-plot and seedlot the sub-plot. Number of emerged seedlings were counted weekly starting in January of each year. There were significant differences between stratification treatments, seedlots and years. The 6-week pre-stratification had the highest germination over 5 years and like the 8-week treatment advanced the average germination date by 20 to 30 days. Nemaguard (65%), Lovell (64%), and Guardian 3-17-7 (60%) had the best germination percent across all treatments and years, with SL2891 (42%) slightly less. All other selections averaged less than 25%. Year-to-year variation was large, indicating strong environmental influences on seed germination despite the pre-stratification treatments.