Background and methodology
The objective of this study was to compare technical management and agronomic performance of peaches in organic and conventional production systems. This study also analyzed relationships between annual nitrogen applications, tree vigor, and crop performances assessed on the basis of yield and fruit quality (polyphenols and sugar content).
A two-year study was conducted (2004 and 2005) in commercial peach orchards located in the middle Rhône Valley of France. Individual fields were selected on the basis of paired comparisons whenever possible: for a given cultivar, an organic plot was located close to a conventional plot with similar soil and climate conditions. The study was implemented on 12 plots cultivated with Spring Lady® (an early cultivar of yellow peach) in 2004 (4 in organic and 8 in conventional), and on 10 plots in 2005 (5 organic and 5 conventional. This protocol was adjusted in 2005 in order to have paired plots (with similar site conditions); as a result, 3 plots were added (1 in organic and 2 in conventional). Fertilization and irrigation practices were recorded on the basis of data provided by farmers and then complemented with interviews.
Nitrogen fertilization and water irrigation levels tend to be lower in organic systems but differences were not statistically significant. The number of suckers in the canopy exhibits a lower vigor in organic orchards, which can be attributed to lower input levels. Organic yields were half of those in conventional and fruit sizes were also smaller.
Organic trees had a limited productive potential, due to a lower initial number of shoots per tree. Fruit polyphenol content differed between the two systems based on fresh matter of the amount of fresh fruit for both cultivars. Organic peaches had a higher polyphenol content, with significant differences shown for Spring Lady® in 2004. There were no significant differences in 2005. Between 2004 and 2005, input levels increased in the organic plots, therefore reducing the gap between organic and conventional in terms of polyphenol content.
Fauriel, J., Bellon, S., Plenet, D. & Amiot, M. J. (2007). On-farm influence of production patterns on total polyphenol content in Peach. Proceedings of the 3rd International Congress of the European Integrated Project Quality Low Input Food (QLIF), University of Hohenheim, Germany, March 20-23 (pp. 122-125). Available on-line at: http://orgprints.org/9855/