© 2007 Heron Publishing—Victoria, Canada
Response of winter root starch concentration to severe water stress and fruit load and its subsequent effects on early peach
fruit development
Gerardo Lopez (1), Joan Girona (1) and Jordi Marsal (1, 2)
1. Institut de Recerca i Tecnologia Agroalimentàries (IRTA), Àrea de Tecnologia del Reg., Avda Rovira Roure, 191, E-25198 Lleida,
Spain / 2. Corresponding author (jordi.marsal@irta.es) / Received November 6, 2006; accepted January 23, 2007; published online August 1, 2007
Summary
Effect of water stress during stage III of peach fruit development on winter root starch concentration (RSC) and subsequent
reproductive development was studied. Two irrigation treatments were applied in two consecutive seasons (2003–2004): full
irrigation (FI) and no irrigation during stage III of fruit development until visible leaf wilting (LWI), which occurred when
midday stem water potential reached –1.80 MPa. Three fruit thinning intensities were applied within each irrigation treatment.
The year 2005 was a recovery year in which all trees received full irrigation and commercial fruit thinning. Water deficit
and high fruit loads in the previous season significantly reduced the concentration of winter RSC. Fruit set and fruit growth
from full bloom to 30 days after full bloom (30 DAFB) increased with increasing winter RSC before other factors, such as inter-fruit
competition and availability of carbon from current photosynthesis, came into play. Consequently, severe water stress reduced
the total number of fruits and fruit dry mass growth 30 DAFB. However, during the recovery year and after fruit thinning,
fruit loads were similar between irrigation treatments and yield capacity remained unaffected. Peach fruit production recovered
quickly from the deleterious effects of two consecutive years of water stress because of a combination of two factors: (1)
reduced initial fruit set that was still adequate to achieve a commercial crop; and (2) the low sensitivity of fruit growth
30 DAFB to winter RSC.
Keywords:
early fruit growth, fruit number, Prunus persica, root reserves, stem water potential.
