Abstract
Modeling is necessary to better understanding of weed management. For this aim, Turgenia litifolia (L.) Hoffm and Datura stramonium L. as two important and problematic weeds germination in wheat and corn fields were compared under temperatures of 0, 5, 10, 15, 20, 25, 30 and 35°C in the germinator, controlled condition included the lighting (12.12 hours and the relative humidity with 30% as of two separate designs in completely randomized design with four replications in the Faculty of Agriculture of Ilam University. Two experiments were carried out twice, the data of the experiments were pooled for analysis, as there was no time-by treatment interaction. Four models, segmented, dent-like, beta and modified beta were used to describe germination changes with respect to temperature. The results showed that four models were significant for T. litifolia germination, and all models were significant on D. stramonium except the beta model. In T. litifolia, suitable germination models were dent-like and beta models. According to dent-like model, base temperature of T. litifolia; was Zero, the first optimum temperature; 15 degrees, optimal second; 29.5 degrees and maximum germination was estimated at 35 degrees. The suitable model for D. stramonium germination was also the segmented model. According the segmented model, the base temperature, optimum temperature and maximum germination were estimated to be zero, 29.7 and 35°C, respectively. Generally, experiment results showing that, for T. litifolia weed management in wheat field, appropriate time for herbicide application is in the range of 15.5–29°C and the appropriate time for D. stramonium management in corn field is mechanical, herbicide application or integrated weed management at time it is 29.7 degrees.