2. Materials and methods
2.1. Plant materials
Stones (seed plus surrounding endocarp) from virus-tested trees of the peach rootstock cultivars, Okinawa (100), Flordagard (300), Green Leaf Nemagard (600), Red Leaf Nemagard (825), and Golden Queen (1100) were obtained from Ausbuds, Victoria. The values in parenthesis refer to the number of chill hours, as defined by Wein berger (1950), for flower bud break and were taken from Okie (1998).