© 2003 Heron Publishing—Victoria, Canada
Influence of branch autonomy on fruit, scaffold, trunk and root growth during Stage III of peach fruit development
Jordi Marsal (1), Boris Basile (2), Luis Solari (3) and Theodore M. DeJong (3, 4)
1. Institut de Recerca i Tecnologia Agroalimentàries (IRTA), Area de Tecnologia Frutícola, Centre UdL-IRTA, Avda Rovira Roure
177, E-25198 Lleida, Spain / 2. Dipartimento di Arboricoltura, Botanica e Patologia Vegetale, Sezione di Arboricoltura, Università degli Studi di Napoli Federico
II, Portici, Napoli, Italy / 3. Department of Pomology, University of California, Davis, CA 95616, USA / 4. Author to whom correspondence should be addressed (tmdejong@ucdavis.edu) / Received December 11, 2001; accepted September 6, 2002; published online March 3, 2003
Summary
We studied the influence of branch autonomy on the growth of reproductive and vegetative organs by establishing different
patterns of fruit distribution within and between large branch units (scaffolds) in mature peach trees (Prunus persica (L.) Batsch cv. ‘Elegant Lady’). Different patterns of fruit distribution were established by defruiting either whole scaffolds
(uneven fruit distribution between scaffolds; US) or several selected hangers (small fruiting branches) per tree (uneven fruit
distribution between hangers; UH). The effects of these patterns were compared with the effects of an even fruit distribution
treatment (EVEN) in which fruits were thinned to achieve maximum uniformity of fruit distribution within the canopy. The desired
fruit loads were obtained by differentially thinning the remaining bearing parts. On a tree basis, the response of mean fruit
mass to fruit load was strongly affected by fruit distribution. The steepest mean fruit mass to fruit load relationship was
found in US trees, whereas the relationship in UH trees was intermediate between the US and EVEN trees. On a scaffold basis,
differences in fruit size between EVEN and US trees with similar fruit loads, though statistically significant, were relatively
small, indicating that scaffolds were almost totally autonomous with respect to dry matter partitioning to fruit during the
final stage of peach fruit growth. Hangers also appeared to exhibit significant autonomy with respect to the distribution
of dry matter during the final phase of fruit growth. Branch autonomy was evident in scaffold growth: defruited scaffolds
in the US treatment grew more than fruited scaffolds, and fruit distribution treatments had little impact on scaffold cross-sectional
area on a tree basis. On the other hand, as observed for fruit growth, branch autonomy did not appear to be complete because
the fruited scaffolds grew more in US trees than in EVEN trees under heavy cropping conditions. However, the effect of fruit
distribution occurred only over short distances, and was negligible on organs located farther away from the source of heterogeneity
(fruits), such as the trunk and roots.
Keywords:
fruit distribution, fruit load, tree water status.
