J.P. PABICO. In Proceedings (CD-ROM) of the Joint 19th Philippine Agricultural Engineering Week, 58th Philippine Society of Agricultural Engineers Annual National Convention, and 6th International Agricultural Engineering Conference and Exhibition, College, Laguna, Philippines, 21-25 April 2008.

Abstract

The Ceres-Rice model requires as inputs crop- and cultivar-specific data that provide coefficients for considering the effects of the gene-environment interactions of a rice cultivar. Crop modelers use two techniques to calculate these coefficients: By trial-and-error, which is tedious to implement and error-prone, even when performed by expert modelers; Or by the use of the Genetic Coefficient Calculator (GENCALC), which uses a deterministic stepwise procedure to automatically adjust the coefficients with values within the plant's realistic physiological ranges, but often results with non-optimal coefficients. This paper presents a procedure that uses selective breeding as a metaphor and guarantees near-optimal coefficients. A breeding program is performed on a population of abstract entities whose genetic codes are the cultivar coefficients. These entities will undergo a series of operations called selective mating and random mutation over a number of breeding generations, allowing them to evolve with coefficients that can provide simulated outputs closer to the experimental trial data. This strategy was used to “breed” the cultivar coefficients in Ceres-Rice using the environmental and management data from actual field experiments conducted in Pila, Laguna in 1985 involving IR58. Using the mean relative error as a measure of closeness of the simulated growth variables to that of the observed data, the result of the simulation using the coefficients found by simulated breeding is closer to the actual trial data than that of the simulation using the coefficients found by GENCALC.

Keywords: Ceres-Rice model, cultivar coefficients, simulated selective breeding, optimization.

Submitted 28 February 2008; Accepted 29 March 2008; Presented 23 April 2008