|Kemanian, Armen - WASHINGTON ST UNIVERSITY|
|Stockle, Claudio - WASHINGTON ST UNIVERSITY|
Submitted to: American Society of Agronomy
Publication Type: Abstract Only
Publication Acceptance Date: August 1, 2005
Publication Date: September 1, 2005
Citation: A SIMPLE METHOD TO SIMULATE HARVEST INDEX IN CROP MODELS. Kemanian, A.R., Stockle, C.O. and Huggins, D.R.. Abstracts 2005 International Annual Meetings American Society of Agronomy, Nov. 6-10, Salt Lake City, UT Technical Abstract: Several methods have been proposed to simulate yield in process-oriented crop models. In this work we present a simple model based on the earlier work of Passioura (1977) and Sadras and Connor (1991). These authors showed that the fraction of water transpired after anthesis is related to the harvest index (HI). While the model is simple, calibration demands measuring transpiration, which is impractical. We propose a simpler model, implicit in the work of the cited authors, that relates HI to the fraction of postanthesis growth (fPAG). A monotonic model HI = HIx ' (HIx ' HIn)exp('k*fPAG), where HIx and HIn are the maximum and minimum attainable HI, and k is a crop or cultivar dependent constant, represents well the response for several data sets of wheat, sorghum and pearl millet. A major advantage of this model is that parameters calibration is readily obtained from biomass measurements at anthesis and at harvest. Values for the parameters are provided and different approaches to simulate yield are compared with this method.