USE OF CROP SIMULATION TO EVALUATE ANTITRANSPIRANT EFFECTS ON TOMATO GROWTH AND YIELD

Abstract

Maximum crop production is closely related to the availability of water. Transpiration may be reduced by theapplication of an antitranspirant (AT) that would increase leaf resistance to diffusion of water vapor. Our objective was todetermine the effectiveness of one of the most promising antitranspirants, Vapor Gard, on tomato production inFlorida. An experiment with three treatments, control plants with no AT application, sprayed with AT only beforeflowering, and sprayed with AT before flowering, at fruit initiation and after first harvest, was conducted at Bradenton,Florida, in 1997. A dynamic, greenhouse tomato, growth and yield model was modified and used to characterize howdifferent plant growth processes are affected by antitranspirant. Parameters in the model were estimated by minimizingsum of squares of error between simulated and observed data for each treatment. Root mean square errors for number ofmain stem nodes, leaf area index, total above ground biomass and fruit dry weight averaged 0.48, 0.17, 35.68g m2, and81.16 g m2, respectively, demonstrating a close fit of the observed data. By using the model, alternate hypotheses todescribe the effects of AT on growth processes were evaluated. It was found that the main effects of AT treatments ontomato plants were on node development and LAI growth, as indicated by differences in model parameters for these twovariables. There was no effect on fruit yield. Most of the vegetative growth response could be explained by an increase inplant temperature likely caused by reduced transpiration by the AT treated plants.