Submitted to: Plant Growth Regulator Society of America Meeting
Publication Type: Abstract Only
Publication Acceptance Date: July 23, 2005
Publication Date: July 24, 2005
Citation: Tworkoski, T., Miller, S.S. 2005. Rootstock effect on growth of apple scion with different growth habits. Plant Growth Regulator Society of America Meeting. July 24-27, 2005. Newport Beach, CA. ABSTRACT NO. 46. Technical Abstract: Rootstocks are used to propagate scion of preferred cultivars, to improve fruit tree tolerance to environmental and biotic stress, and to control tree size. The goal of the current experiment was to improve understanding of rootstock effects on apple scion with different growth habits to assist with management and with rootstock breeding of apple trees. Scion had more influence on monthly growth rate than rootstock. Scion with spreading growth habits grew rapidly in April and May and achieved most seasonal growth earlier than scion with upright growth habits that grew slowly early in the season. In all growth habits and rootstocks, growth rate slowed appreciably, but did not cease by August and growth did not terminate earlier for any one scion. The dwarfing rootstock, M.9, consistently had the lowest, and seedling rootstock had the greatest tree height and diameter. However, no one size controlling rootstock consistently regulated date of bud break, full bloom, shoot elongation rate, or duration of growth. The large number of interactions between scion with different growth habits and different size-controlling rootstocks indicated that rootstocks may differentially regulate components of apple tree growth.