Investigating the history and long term effect of climatic factors on saffron production in Khorasan Razavi province

Saffron (Crocus sativus L.) has been used as food and medicine for Iranians for a long time, from the ancient to the modern period, and several factors have influenced its production and consumption in different provinces, especially Razavi Khorasan. In order to investigate the trend of cultivated area, stigma production and yield of saffron and also the effect of climatic parameters such as altitude above sea level, average temperature, and precipitation on the cultivation and production of this plant in different cities of Khorasan Razavi Province, a study was conducted by using data of Agricultural Jihad Organization during 1984 to 2020. Results indicated that the highest production and cultivated area in the province of Razavi Khorasan in the studied period were related to Zaveh, Torbat Heydarieh, and Roshtkhar, respectively. Zaveh and Torbat Heydarieh also had the largest portion of irrigated production in the province, with 13.3 and 9.4 %, respectively. Upon comparing the yield of saffron across different cities to the provincial average, it became evident that Gonabad and Torbat Heydarieh secured the first and second positions, respectively, in this comparison. Conversely, Kalat exhibited the lowest percentage in terms of cultivated area, irrigated production, and yield ratio compared to the provincial average. Further analysis revealed that elevation above sea level is positively correlated with both cultivated area and saffron production. Interestingly, there exists a non-linear inverse relationship between annual rainfall and cultivated area, production, and yield of saffron. Moreover, the study found that higher average temperatures are associated with increased saffron production, although the average yield of saffron tends to decrease. Regarding similarities across different cities in Khorasan-Razavi province, an investigation at a 75% similarity threshold indicated the possibility of classifying the province's various regions into five distinct clusters. The cities of Bakharz, Gonabad, Kashmer, Mahvalat, and Roshtkhar were in the first cluster, and the cities of Bajastan, Khaf, Torbat Jam, Neishabur, Bardaskan, and Taibad were in the second cluster, and each of the cities of Torbat Heydarieh and Zaveh also formed two separate branches. The rest of the cities were placed in a cluster. In general, the increasing trend of saffron cultivation and production in Khorasan-Razavi province indicates a greater desire to cultivate this plant by the farmers, considering the climatic and soil conditions of this province.