the geographical distribution of growing degree-days (gdds) within iran was studied using gis-based maps. gdds were calculated using daily thermal parameters (daily maximum and minimum air temperature). based on the purpose of the study and climatic conditions of iran, the average value of 5?c was chosen for gdd calculation. the calculations were carried out using daily weather data of 113 mete...

given the important role of crop growth indices for explanation of cultivars yield differences in diverse environmental and agronomical circumstances, this experiment was conducted at research field of tarbiat modares university during 2007 growing season. experimental treatments were arranged in split-plot layout based on randomized complete blocks with four replications. in this research, sow...

Heat units, expressed in growing degree-days (GDD), are frequently used to describe the timing of biological processes. The basic equation used is GDD = [(T,,, + TM,,)/2] T,,,,, where T, and T,,, are daily maximum and minimum air temperature, respectively, and T,, is the base temperature. Two methods of interpreting this equation for calculating GDD are: (1) if the daily mean temperature is les...