Investigation of climatic factors of Azadshahr township (Golestan province) in order to development of saffron cropping

In order to investigation of climatic factors in Azadshahr township (Golestan province) for development of saffron cropping, spatial analysis of geographic information system (GIS) was used. In first, thematic maps of climatic variables included annual rainfall, rainfall of reproductive, rainfall of growth period, annual average temperature, maximum temperature of reproductive period, maximum temperature of growth period, minimum temperature of reproductive period, minimum temperature of growth period, minimum temperature of dormancy, sunshine hours, relative humidity and number of frost days were provided. In this research, climatic data from 137 synoptic, climatology and rain-gauge stations were used. For estimation of these variables, geostatistic and classic interpolation methods included Kriging, Inverse Distance Weighting (IDW) and Local Polynomial Interpolation (LPI) were used and the best method was selected according to RMSE and GSD in ArcGIS media. Results showed that total boundary of this township was classified based on annual rainfall in three classes included high suitable, suitable, and semi-suitable zones for saffron cropping. Also, in the viewpoint of the rainfall of reproductive, about 74.48% of agricultural lands in central and north of this township was located in non-suitable zone. But, some variables such as rainfall of growth period, annual average temperature, maximum temperature of reproductive period, minimum temperature of reproductive period, minimum temperature of growth period, minimum temperature of dormancy, sunshine hours and number of frost days had not the limitation for development of saffron cropping. Assessment of obtained results by field survey from current saffron fields were determined that the all sampling points located in high suitable and suitable zones of climatic maps. In general, development of saffron cultivation is possible in south area of Azadshahr township.