calibration of the gompertz and logistic models to determine the critical period of weed control

the effect of weeds on yield of plants is variable during the plant growing periods. recognition of these critical periods is basically important for weed control. the gompertz and logistic are two mathematical models, which are suitable to study the presence of weed effect on the yield of plants. the main problem of using these models is calibration. in this study, a method is developed for model calibration and calculation of the parameters. the data from an experiment on tomato used in order to calculate the parameters considering five percent reduction in yield, and critical period of weed controls was determined. the results indicated that the models accurately determined the most critical stage of plant growth for weed control.