Simulation model of the growth of sweet orange ( Citrus sinensis L. Osbeck) cv. Natal in response to climate change

Abstract

The objective of the present study was to develop a simulation model of the growth of sweet orange (Citrus sinensis L. Osbeck) cv. Natal in response to climate change based on system dynamics principles. The model was developed based on a system analysis of the factors that affect crop biomass formation. The main variables considered were atmospheric carbon dioxide (CO₂), air temperature, transpiration, rainfall, water deficit, irrigation depth, canopy volume, and the respective interrelationships. Simulations were performed for the period from 2010 to 2100. Overall, the model results indicate that the increase in atmospheric CO₂ concentrations predicted in the Intergovernmental Panel on Climate Change (IPCC) report, combined with air temperatures higher, lower, or equal to those generally occurring in natural environments, will result in higher water use efficiency by orange trees. When other factors, such as the soil water deficit, were included in the model, the water productivity was predicted to be lower in 2100 without irrigation than when irrigation was included. It is concluded that the model is suitable for determination of the effects of climate change on water use efficiency of sweet orange cv. Natal. Increased atmospheric CO₂ concentrations will result in higher CO₂ assimilation in orange trees and therefore in increased biomass production (g) per unit of water transpired (mm). However, this positive effect may be masked by other effects of atmospheric CO₂ increases, mainly those associated with temperature.

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