Algorithm for estimating cultivar-specific parameters in crop models for newer crop cultivars

Authors: BEEGUM, SAHILA - University Of Nebraska; REDDY, RAJA KAMBHAM - Mississippi State University; Reddy, Vangimalla

Submitted to: European Journal of Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/6/2024
Publication Date: 8/9/2024
Citation: Beegum, S., Reddy, R., Reddy, V. 2024. Algorithm for estimating cultivar-specific parameters in crop models for newer crop cultivars. European Journal of Agronomy. 160: Article e127308. https://doi.org/10.1016/j.eja.2024.127308.
DOI: https://doi.org/10.1016/j.eja.2024.127308

Interpretive Summary: Crop simulation models use different parameters related to specific cultivars. Typically, these parameters are determined through controlled experiments that investigate the growth and development of different cultivars. As new cultivars with improved growth traits are produced every year, there is a need to create custom parameters for these new varieties. In the present study, a standard algorithm that can be used for any type of crop model to estimate these cultivar-specific parameters is developed. This algorithm is demonstrated using the cotton crop model and 40 recently developed cotton cultivars. To analyze the variation in crop growth features among the 40 cultivars, experiments are carried out to grow all the cultivars in the same environmental and management conditions. The GOSSYM crop simulation model is utilized to demonstrate the functionality of this method. The newly developed technique has proven to be efficient in estimating cultivar-dependent parameters. This same methodology can be applied to other crop models.

Technical Abstract: Model parameters in mechanistic process-based crop models are broadly classified into general parameters (environmental and management parameters and parameters related to soil processes), species-specific parameters, and cultivar-dependent parameters. While general and species-specific parameters typically remain unchanged, identifying cultivar-dependent parameters is crucial during calibration. With the continuous development of new cultivars designed to address diverse agricultural needs and challenges, it becomes necessary to update cultivar-specific parameters in crop models accordingly. However, gathering data on the behavior of these newer cultivars and calibrating the model to accommodate them is challenging. Currently, there is no standard systematic approach for determining cultivar-specific parameters in crop models due to the difficulty of identifying variations in the growth and development process in newer cultivars, as well as the variations in the model structure, correlations between sub-model components and between different parameters in the crop models. The present study develops a standard methodology for determining cultivar-dependent parameters based on experiments and incorporating them into process-based crop growth models. The developed method is demonstrated using the cotton crop and the GOSSYM model (mechanistic process-based cotton crop model). Experiments are conducted on 40 major cotton crop cultivars grown in the USA to quantify their growth and development under the same environmental and management conditions. Based on the experimental data, cultivar-dependent parameters are derived and integrated into the GOSSYM model. By establishing a standardized methodology and demonstrating its application in the context of cotton and the GOSSYM model, this study provides practical guidance for incorporating cultivar-dependent parameters into crop simulation models. Researchers and agronomists can effectively utilize this methodology to integrate new cultivars into their crop models.