Modeling productivity of Zacatecan peaches
2002
Esparza, G. | Gallegos, C. | Rumayor, A. | DeJong, T.M.
Most of the commercial peach production in the central-north Mexican highlands (about 20,000 ha) is located in the state of Zacatecas and is based on "Criollo" seedling peach trees. Peach yields in this region are, in general, low and variable and peach productivity potential is unknown. The objective of this research was to simulate productivity of Zacatecan peaches and compare it with that obtained in California. Our approach was to adjust the existing PEACH model developed at the University of California, Davis for Californian cultivars. PEACH is a carbon balance model that allows integration of genotype, environment and orchard management aspects, all being important for predicting productivity. Zacatecan cultivars differ architecturally and physiologically from Californian cultivars due to both genetic and orchard management induced causes. In this study, model simulations were run for both the Californian mid season maturing cv. 'Cal Red' and the Zacatecan mid season cv. 'Criollo' growing in Fresno CA, USA and Jerez, Zac. Mexico. Model modifications focused on the environmental parameters and the fruit growth potential equations. The model simulates carbon assimilation as function of solar radiation, minimum and maximum temperatures, degree days, tree light interception, leaf area index and photosynthetic rates. Simulation of respiration, growth and carbon partitioning integrate the organ carbon demand. Results show that the Zacatecan environment may restrict productivity of cv. 'Cal Red' up to 22.0 %. Crop growth limitations were predicted mostly during the final two thirds of the growing season. Yield reductions of 'Criollo' peaches was predicted to be low with a productivity for this cultivar representing just 39.9% that of 'Cal Red'. New avenues of applied research to increase productivity of Zacatecan peaches were identified.
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