Predicting of Wild buckwheat (Polygonum convolyulus L.), Alkafaun (Fumaria vaillantii Lois) and field bindweed (Convolvulus arvensis L.) Seedling Emergence with using Thermal model in Karaj

Prediction of weed emergence timing would help reduce herbicide use through the optimization of the timing of weed control. In order to predict the emergence of wild buckwheat (Polygonum convolyulus L.), alkafaun (Fumaria vaillantii Lois) and Field bindweed (Convolvulus arvensis L.) by using the temperature model, an experiment was conducted at wheat field research of university of Tehran, Karaj during 2012-13. Based on the results, 50 percent of cumulative emergence of wild buckwheat were obtained in 75.21, 71.48 and 75.21 growing degree day at inner margin, center and outer margin of wheat field, respectively. The presence of wheat was not impressed the emergence of wild buckwheat. It was for that this weed was not required light for germination. Alkafaun emergence was happened at higher growing degree day at inner margin of field. Of course alkafaun had lower emergence per received GDD at outer margin in comparison with other parts of the field. Although emergence had lower slope per growing degree day at this part, but it was achieved to 50 percent cumulative emergence with lower received GDD. It was this time that 50 percent cumulative emergence of alkafaun achieved with 49.11 and 45.90 GDD at center and outer margin of field, respectively. Field bindweed was achieved to 50 percent of cumulative emergence with 158.98 and 150.60 growing degree day at inner margin and center of field. but there was no direct correlation between the number of weeds in the wild buckwheat seed bank and the number of seedlings were emerged.