PEACH TREE VIGOR IS A FUNCTION OF ROOTSTOCK XYLEM ANATOMY AND HYDRAULIC CONDUCTANCE
Recently we have demonstrated that there are anatomical differences between dwarfing and vigorous peach rootstocks. These differences in xylem anatomy have been linked to the vigour control capacity of the specific rootstocks. Previously we showed that dwarfing peach rootstocks generally have lower mid-day stem water potentials and that this limits shoot growth during the most active period for vegetative growth. The key factor affecting shoot growth appears to be stem hydraulic conductance which is strongly influenced by xylem vessel diameters. Weighted mean xylem vessel diameters are smaller in dwarfing rootstock genotypes than in vigorous ones. Thus it appears that xylem vessel diameter is a genetically controlled, phenotypic trait that is the primary factor that determines the size-controlling capacity of graft-compatible peach rootstocks. This paper will summarize the physiological and anatomical evidence for this hypothesis that provides a mechanistic basis for under¬standing the size-controlling phenomenon associated with graft-compatible peach rootstocks. This mechanistic explanation of the size-controlling phenomenon provides researchers with a useful means to screen for size-controlling genotypes in rootstock development programs. Furthermore it may be the basis for the future investigation of vigour-related phenomena in other fruit tree species.
Tombesi, S., Marsal, J., Basile, B., Weibel, A., Solari, L., Johnson, S., Day, K. and DeJong, T.M. (2012). PEACH TREE VIGOR IS A FUNCTION OF ROOTSTOCK XYLEM ANATOMY AND HYDRAULIC CONDUCTANCE. Acta Hortic. 932, 483-489
dwarfing, size-controlling, growth