A new modified resource budget model for nonlinear dynamics in citrus production

• A theoretical modeling and simulation study of the nonlinear dynamics in citrus is conducted.• New leaf growth is incorporated into the model as a major factor responsible for the yield oscillations.• A Ricker-type equation for the relationship between costs for flowering and fruiting is proposed.• A generic form of the resource budget model for the nonlinear dynamics in citrus is obtained.• The new model is tested with experimental data for two citrus trees.

Alternate bearing or masting is a general yield variability phenomenon in perennial tree crops. This paper first presents a theoretical modeling and simulation study of the mechanism for this dynamics in citrus, and then provides a test of the proposed models using data from a previous 16-year experiment in a citrus orchard. Our previous studies suggest that the mutual effects between vegetative and reproductive growths caused by resource allocation and budgeting in plant body might be considered as a major factor responsible for the yield oscillations in citrus. Based on the resource budget model proposed by Isagi et al. (J Theor Biol. 1997;187:231-9), we first introduce the new leaf growth as a major energy consumption component into the model. Further, we introduce a nonlinear Ricker-type equation to replace the linear relationship between costs for flowering and fruiting used in Isagi's model. Model simulations demonstrate that the proposed new models can successfully simulate the reproductive behaviors of citrus trees with different fruiting dynamics. These results may enrich the mechanical dynamics in tree crop reproductive models and help us to better understand the dynamics of vegetative-reproductive growth interactions in a real environment.