GOSSYM as a Pima Simulator

J.M. McKinion, K.R. Reddy, and H.F. Hodges


 
ABSTRACT

Gossym has been used across the cotton belt in the management o "Delta" cottons (Gossypium hirsutum), in particular the Stoneville, DPL, DES, and Acala varieties. GOSSYM has now been extended to simulate the Gossypium barbadense variety S6. For the past two growing seasons, experiments have been conducted in the controlled environment plant growth chambers of the USDA-ARS Crop Simulation Research Unit under research contract with SUPIMA of America to delineate morphological and growth rate equations for PIMA S6.

This paper discusses the results of these experiments where the data have been summarized as curvilinear graphs for most of the major phenological events. Data is presented for time between events for first square, first bloom, first open boll, prefruiting nodes, fruiting nodes, and fruiting branch nodes as a function of temperature. Data is also presented relating the reduction of mainstem elongation as a function of node age is also presented. net photosynthesis reduction as a function of leaf water potential is also presented.

An initial comparison of simulated model results using the generic "MID" season cotton calibration variety file and the new "PIMA" variety" Variety file with growth and morphogenetic equations incorporated into Gossym from the above date with field data on PIMA S6 collected on the Plant Science Farm at Mississippi State, MS has been made with promising results. The PIMA variety file allowed the simulation to match the real data much more closely than the MID variety file; however, this data was used to calibrate the PIMA model and does not represent a true validation of the model. Additional data sets well be used in the next several months to validate the PIMA model. The PIMA model will be field tested in WEST Texas, New Mexico, Arizona, and California during the summer of 1992.



Reprinted from 1992 Proceedings Beltwide Cotton Conferences pg. 1365
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998