SORGHUM AND SUNFLOWER EVAPOTRANSPIRATION AND YIELD FROM SIMULATED LEAF-AREA INDEX

Accurate prediction of evapotranspiration and crop yield is essential for good water management. This paper describes the structure and test ing of PILOTE 1.3, an operative water balance model which predicts act ual evapotranspiration (AET) and yield of crops. The model simulates t he LAI, leaf area index, using a water stress index and thermal time w hich is calculated from air temperature. A previous model PILOTE 1.2 d escribed by [Mailhol, J.C., Ruelle, P., Revol, P., 1996a. PILOTE: Un m odele operationnel pour deceler l'apparition du stress hydrique. 16th International Congress on irrigation and Drainage (ICID-CIID). 47th In ternational Executive Council Meeting. Workshop on Crop-Water-Environm ent Models. Cairo international Conference Centre Cairo-Egypt, Septemb er 17, 1996. 15-22 Sept. 1996. pp. 209-222; Mailhol, J.C., Ruelle, P., Revel, P., Delage, L., Lescot, J.M., 1996b. Operative Modelling for A ctual Evapotranspiration Assessment: Calibration Methodology. ASAE Pro ceeding of ASAE. San Antonio, TX, 3-7 Nov., 1996. pp. 474-479] is used as a sub-model and calculates the water stress index. The simulated L AI values generate crop coefficients corresponding to actual local con ditions. Data obtained from field experiments carried out at Montpelli er (FRANCE) on sorghum (Sorghum bicolor (L.) Moench) in 1990 and 1992, and on sunflower (Helianthus annuus L.) in 1994 and 1995 were used fo r the model calibration. When tested against independent data the mode l generates reliable predictions of actual evapotranspiration and yiel ds of sorghum and sunflower (r(2) > 0.93). (C) 1997 Elsevier Science B .V.