the estimation of phenological thresholds of saffron cultivation in isfahan province based on the daily temperature statistics

in this research, the statistics of daily temperature of meteorology stations for estimating the probable occurrence of the first and last frost temperature, the phonological thresholds of saffron and its flowering and irrigation dates were explored. furthermore, by applying different methods, the probabilities of the attained dates in different probability levels were fit in smada software. the estimated probability level of 95 percent, as the optimum date, was donated for the entire isfahan province in arcgis9/3 software environment using the interpolation method of cokriging. the time of occurrence of minimum temperatures is under the influence of the geographical and height condition of each region and the first fall season frost occurs in high regions of the eastern half of isfahan province at the beginning of november and in the low-lying eastern regions in the late december. the occurrence of daily temperature is changeable from the first half of october and the second half of november. from the west to the east of isfahan, the time of occurrence of this threshold has a delay of about one month. the optimum flowering date of saffron, based on climatic conditions, is from the first half of october to the late of november. by considering the flowering date and daily temperature requirement of saffron, the irrigation date prior to flowering continues from the second half of september in the western parts and the beginning of november in the eastern regions. from the perspective of thermal condition, the western, central, northern and eastern parts of isfahan province are more suited to the cultivation and development of saffron product. the amount of water requirement in the study area based on evapotranspiration and crop coefficients of saffron occurred in the mid-season, late season and initial.