HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by White, J. W. Articles by Hunt, L. A. Search for Related Content PubMed Articles by White, J. W. Articles by Hunt, L. A. Agricola Articles by White, J. W. Articles by Hunt, L. A. Related Collections Crop Growth and Development Temperature Stress Crop Physiology & Metabolism Global Change Crop Models

Agronomic Modeling

A Structured Procedure for Assessing How Crop Models Respond to Temperature

^a USDA-ARS, U.S. Water Conserv. Lab., 4331 E Broadway Rd., Phoenix, AZ 85040-8834
^b Dep. of Biol. and Agric. Eng., College of Agric. and Environ. Sci., Griffin Campus, The Univ. of Georgia, Griffin, GA 30223-1797
^c Dep. of Plant Agric., Crop Science Bldg., Univ. of Guelph, Guelph, ON, Canada N1G 2W1

^* Corresponding author (jwhite{at}uswcl.ars.ag.gov)

Received for publication March 22, 2004. Crop simulation models are widely used to analyze temperature effects on crop growth, development, and yield. Unfortunately, temperature responses of models often are not examined critically to ensure that a model is appropriate for a given research application. This paper describes a procedure for assessing how models respond to temperature. The procedure treats major processes in a balanced fashion but does not require access to source code. The results are easily interpretable by nonmodelers and readily documented and employed with different models. Sensitivity analyses are run using standardized conditions of nonlimiting water and N with regimes of constant mean temperatures from 3 to 40°C and daily range of 10°C. Daily model outputs define responses that are grouped in seven categories: crop mass (including economic yield), phenology, reproductive growth, canopy development, root growth, resource use efficiency, and water balance. To avoid interactions of duration of life cycle with growth, several responses are assessed before partitioning to reproductive growth reduces total aboveground biomass. Emphasis is on graphical analysis of individual variables vs. mean temperature, but cardinal temperatures and a response index are also estimated. When applied to the CSM-CERES-Sorghum and CSM-CROPGRO-Drybean models, the procedure readily identified differences in temperature adaptation of the two crops. Various examples were found where modeled responses appeared to differ from data from field or controlled-environment studies. The proposed procedure will require adjustments for specific situation but provides a foundation for assessing modeled responses to temperature in a structured and reproducible fashion.

Abbreviations: CGR₅₀, crop growth rate measured at the reference date of 50 days after emergence • DAE, days after emergence • HI, harvest index • LAI₅₀, leaf area index at the reference date of 50 days after emergence • NUE, nitrogen use efficiency • RSI, response stability index • RUE, radiation use efficiency • RUE₅₀, radiation use efficiency at the reference date of 50 days after emergence • SLA₅₀, specific leaf area at the reference date of 50 days after emergence • T_base, base temperature • T_max, maximum temperature • T_opt1, first optimal temperature • T_opt2, second optimal temperature • TCM_anth, total aboveground crop mass at anthesis • TCM_harv, total aboveground crop mass harvest • TCM₃₀, total aboveground crop mass at reference date of 30 days after emergence • TCM₅₀, total aboveground crop mass at reference date of 50 days after emergence • WUE_ET, water use efficiency at the reference date of 50 days after emergence, based on evapotranspiration • WUE_TR, water use efficiency at the reference date of 50 days after emergence, based on transpiration