Low vigor peach x almond rootstocks for intensive peach plantings in Mediterranean environments

A three-year trial was carried out to evaluate the vegetative and productive performance of five peach rootstocks of varied vigor. The study was conducted in south-western Sicily using 45 V-trained trees of 'Tropic Snow' peach planted in 2005 and grafted on GF677 and four low-vigor rootstocks selected at the Department of Agricultural, Food and Environmental Sciences, University of Pisa, namely IS5/8 (Polluce), IS5/19 (Castore), IS5/23, IS5/29. Trunk circumference, winter and summer pruning weight, number and mass of fruit were recorded from 2010 to 2012. All IS selections reduced trunk cross-sectional area (TCSA) and pruning weight compared to GF677 with IS5/23 inducing the highest reduction of TCSA by 2012. Yield efficiency was increased by all IS selections but IS5/29, with IS5/23 the most efficient. Trees on IS5/23 exhibited 15-25% reductions of crop load and yield, whereas only IS5/29 induced fruit size similar to GF677. Overall, all low-vigor rootstocks performed well, and in particular IS5/29 exhibited a good compromise between growth reduction and yield while maintaining good fruit size. The most dwarfing IS5/23 may represent a valid alternative to GF677 for very intensive peach plantings in dry Mediterranean areas.