Identification relevant areas for saffron cultivation according to precipitation and relative humidity in South Khorasan using GIS

In order to grow plants in any region، suitable weather and climatic condition are required. Climatic parameters such as precipitation، temperature and humidity have significant roles in the growth and yield in a region; therefore، understanding the climate and analyzing the ecophysiological characteristics of plants are the most important factors in the yield of the plant. Saffron is one of the profitable plants in South Khorasan. The yield of saffron from this region has caused Iran to be the targets producer of this plant in the world. The significance of planting saffron in Iran is related to many factors such as the high efficiency of water usage and employment of villagers. The analysis of the effect of climatic parameters on the saffron yield and determining the suitable areas for planting this plant according to these parameters are important for agriculture and economy. The statistics and data of 20 years taken from the Weather Station in the region and the 10 years saffron yield were used. Regression analysis and create of equation using precipitation، relative humidity، and the relation between these parameters was accomplished by the use of JMP 4 software. Digitized climate zonation maps were made by Arc GIS 9. 2 software. The results showed that precipitation was most effect on the saffron yield during the months of December، Feburay، March and April compared with the other months and considering humidity، the most affected months are October، November، Decmber، January and February. Also، after analyzing the equation and the climate zonation maps and the final map، it became obvious that the most of the areas of the Province were able to be ranked as suitable. The North and North-Eastern regions were the best areas regarding the parameters discussed in order to grow saffron. The center of province were considered average region to grow saffron and the Southern and South-Western areas were determined the least suitable for growing saffron.