Investigating the long-term effect of climatic factors on the cultivation of cumin in Razavi Khorasan province with a brief look at the importance of the historical geography of this plant

Introduction
According to the available statistics, the cultivated area, production and yield of cumin in Khorasan Razavi province in 2021 were 8226.5 hectares, 4213.14 tons and 512, respectively, and in rainfed conditions, 3349.5 hectares 672.89 tons and 201 kg.ha-1. Climate is one of the most important factors in the geographical distribution of plant species and the production of agricultural products depends on climatic conditions. This study aimed to investigate the trend of cultivated area, production and yield of cumin in different cities of Razavi Khorasan province and the effect of climatic parameters on it during 1995-2020.

Materials and Methods
In order to investigate the trend of cultivated area, production and yield of cumin medicinal plant and also the effect of climatic parameters such as altitude above sea level, average temperature and average precipitation on the cultivation and production of this plant in different cities of Razavi Khorasan province, a study was conducted between 1995 and 2020 using the data received from Razavi Khorasan Agricultural Jihad Organization.
The studied cities include Bakhrez, Bajestan, Bardeskan, Taibad, Torbat Jam, Torbat Heydarieh, Joghtai, Joyn, Chenaran, Khalil Abad, Khaf, Khoshab, Davarzen, Dergz, Rashtkhwar, Zaveh, Sabzevar, Sarkhas, Saleh Abad, Freeman, Firuzeh, Qochan, Kashmer, Kalat, Gonabad, Mashhad, Mehvelat and Neyshabur. In this research, the trend of changes in cultivated area, production and yield of irrigated and rainfed cumin plants was studied in cities and years in the desired time period. For this purpose, the regression relationship of cultivated area, cumin production and yield of each city with climatic parameters was drawn. Also, the similarity percentage of the cities of Razavi Khorasan province in terms of yield, production and cultivated area factors was investigated at the similarity level of 75%.

Results
The results showed that among the cities of the province, Sabzevar had the highest percentage of irrigated area, percentage of irrigated production and ratio of irrigated and rainfed yields to the average of the province. The highest percentage of the total cultivated area and rainfed production of cumin was also allocated to Taibad. Also, the lowest percentage of cultivated area and irrigated production of this product was observed in Dargez.
According to the results of the research, the production of this product in irrigated and rainfed condition during different years in cities of the province was different and had changes, which may be one of the reasons for that, the existence of weather fluctuations and the effect of climatic parameters on production. Among the cities of the province, Sabzevar and Taibad had the highest average production of irrigated and rainfed cumin during 1995 to 2020, respectively.
Climatic parameters such as altitude above sea level, precipitation and temperature were effective on the cultivated area, production and yield of cumin, so that with the increase of climatic parameters, the investigated traits of cumin showed an increasing trend. In the clustering of different cities of Khorasan Razavi province, in terms of cultivated area, production and yield of cumin, the cities of the province were placed in 7 clusters. The first cluster included the cities of Bakhrez, Zaveh, Fariman, Bajestan, Joghataie, Roshtkhar, Jovein, Chenaran, Darghz, Torgabeh-Shandiz, Sarkhs, Qochan and Kalat. The cities of Torbat Heydarieh, Khaf, Khalilabad, Firuzeh, Saleh Abad, and Mashhad were placed in the second cluster, the cities of Bardaskan and Torbat Jam in the third cluster, the cities of Khoshab and Neyshabour in the fourth cluster, and Gonabad and Mahvalat in the fifth cluster. The cities of Taibad and Sabzevar were also placed in separate branches.
Conclusions
According to the results of the research, the cultivated area, production and yield of cumin medicinal plant were different under the influence of climatic parameters and in the investigated time period in different cities of Razavi Khorasan province, but in general, the cultivated area and production of this plant in Sabzevar was more than another regions of this province. Also, with the increase in altitude above sea level, rainfall and temperature, the cultivated area and water production of this product showed an increasing trend.
It should be noted that choosing products that are climatically compatible with the region and also are better economically can help the farmer's production stability.