Agronomie 24 (2004) 493-501
DOI: 10.1051/agro:2004046

Simulation of individual leaf areas in grain sorghum

W.D. Rosenthal^a and R.L. Vanderlip<sup>b

a</sup>  Blackland Research Center, Texas Agricultural Experiment Station, 720 East Blackland Road, Temple, TX 76502, USA
^b  Agronomy Department, Kansas State University, Manhattan, KS 66506, USA

(Received 22 November 2003; accepted 22 July 2004)

Abstract - Most crop simulation models that incorporate environmental conditions estimate leaf area development. The grain sorghum growth simulation model, SORKAM, calculates individual leaf area based on leaf number and maturity class. The objective of this study was to generalize present leaf growth routines in SORKAM to be independent of maturity since there are no generally accepted maturing classes. Modified relationships between leaf number and leaf growth parameters were developed from existing studies and were tested against independent detailed leaf growth data sets. The revised relationships improved the r² between simulated and actual individual leaf areas from 0.80 to 0.88, reduced the bias from 32 cm² to 9 cm², and the RMSE from 80 cm² to 52 cm². With the improved simulation, estimated leaf area index through the season was also improved from the original SORKAM estimate (RMSE decreased from 0.77 to 0.63; RMSE: root mean square error). Although simulation of individual leaf areas was improved, total leaf area produced over the season was not.

Key words: grain sorghum / leaf area / modeling

Corresponding author: W.D. Rosenthal rosentha@brc.tamus.edu

© INRA, EDP Sciences 2004