Seasonal effects of light exposure, temperature, trunk growth and plant carbohydrate status on the initiation and growth of epicormic shoots in Prunus persica

Understanding the physiology of epicormic sprout initiation and growth is economically important for arboricultural management. In this experiment, factors influencing the initiation and growth of epicormic sprouts, including light exposure, temperature, trunk growth, date of green pruning, and tissue concentrations of non-structural carbohydrate, were investigated in Prunus persica. Field trials were conducted in Rome, Italy, during the 2004 growing season, using transparent, silver or black cage treatments to manipulate the light and temperature environment experienced by topped trees. Each month, non-structural carbohydrate (NSC) concentrations were measured in bark, wood and root tissues, and the number of epicormic sprouts produced per tree and the dry weight (DW) per sprout was recorded for a fresh group of topped trees. Date of pruning, light exposure, node number present in the stump, estimated bark NSC, and estimated xylem NSC were significantly related to the number of sprouts formed. Cage temperature, trunk volume, and trunk diameter growth did not significantly affect the number of sprouts formed. Date of pruning, light exposure, and estimated bark NSC were significantly related to the DW per sprout. Temperature, trunk volume, trunk diameter growth, and estimated wood NSC did not significantly affect the DW per sprout. Date of green pruning appeared to be the most important factor to explain sprouting behaviour, leading to the conclusion that correct timing of Summer pruning may reduce subsequent epicormic sprouting.