Base temperatures for germination of selected weed species in Iran

Weed emergence models require the estimation of base temperature for germination (T-b) that was estimated for Abutilon theophrasti, Echinochloa crus-galli, Amaranthus retroflexus, Sorghum halepense, Amaranthus albus, and Amaranthus hybridus in Iran, to calibrate an existing model called AlertInf. Two statistical procedures were adopted: Model 1 - linear regression of germination rate and Model 2 - probit analysis. Model 1 provided lower T-b values. Abutilon theophrasti and A. hybridus presented lower T-b values (about 4 and 8 degrees C), while the remaining species had values above 10 degrees C. Since the estimated values of T-b were in agreement with those adopted for the Alertinf model in Italy, the first step was achieved to adapt AlertInf to Iranian conditions.