Journal of Geographical Studies of Mountainous Areas

Journal of Geographical Studies of Mountainous Areas

Evaluating the efficiency of the WOFOST model to determine the effective climatic potential on rapeseed yield in Lorestan province

Document Type : Original Article

Authors
Mahdi Sahnalizadeh 1
Behrouz Nasiri 1
Sajjad Rahimi-Moghaddam 2
Mostafa Karampour 1
1 Department of Geographical Sciences, Faculty of Literature and Humanities, Lorestan University, Khorramabad, Iran.
2 Department of Plant Production and Genetics Engineering, Faculty of Agriculture, Lorestan University, Khorramabad, Iran.
10.22034/gsma.2026.2066586.1108
Abstract
1. Introduction
Rapeseed (Brassica napus L.) is known as the third most important oilseed crop in the world and is cultivated in a wide range of fields around the world due to its good characteristics such as resistance to drought, salinity, and cold, high rotation value, and high ability to compete with weeds. An acceptable share of the country's water resources (about 12 percent) on the one hand and favorable precipitation on the other hand have made it possible to cultivate and increase the cultivated area and production of rapeseed in Lorestan province. There are various approaches to assessing crop cultivation potential, including the direct approach of cultivating the crop in different years and regions, which would not be a suitable choice due to its high cost and time-consuming nature. Another approach for determining the potential of regions is to use a modeling approach and estimate the ability of each region to produce the desired crop. Accordingly, the present study aimed to evaluate the WOFOST model in simulating rapeseed growth and yield and identifying potential areas suitable for rapeseed cultivation in different counties of Lorestan province, considering different climatic variables.

2. Methodology
This research was conducted in the counties of Azna, Aleshtar, Aligudarz, Borujerd, Pol-e Dokhtar, Khorramabad, Dorud, Kuhdasht, and Nurabad located in Lorestan province. The WOFOST model was used to simulate the growth and development of rapeseed. The statistical indices of nRMSE, d-index, and MBE were used to evaluate the model. Finally, zoning maps of rapeseed yield, rapeseed growth period, and climatic variables (average minimum temperature, average maximum temperature, and average annual precipitation) in Lorestan province were drawn using GIS 10.8 software.

3. Results
The results of the calibration and validation showed that the WOFOST model simulated the growth and yield of rapeseed with high accuracy under potential and water-limited conditions. The soil moisture storage calculated by the model under full irrigation (irrigated cultivation) and rainfed cultivation were compared with the actual amount. In this evaluation, the WOFOST model was able to estimate the amount of stored moisture in the soil reasonably well. The highest average minimum temperature in the studied areas, with an average of 16.8 °C, belonged to Pol-e Dokhtar county, while the counties of Azna (5 °C) and Aligudarz (6.4 °C) in the eastern half of the province and the counties of Aleshtar (6.2 °C) and Nurabad (4.9 °C) in the north of Lorestan province had lower average minimum temperatures. In Lorestan province, the highest average annual maximum temperature was observed in the south of the province (Pol-e Dokhtar county with an average of 28.8°C), while the eastern regions (Azna and Aligudarz with averages of 20.6°C and 19.9°C, respectively) and the northern regions (Borujerd and Nurabad with averages of 22.1°C and 19.5°C) had lower average maximum temperatures than other regions of the province. Precipitation ranged from 373 mm in Pol-e Dokhtar county to 643 mm in Dorud county. The longest growing season was observed in Azna, Aligudarz, and Nurabad counties with an average of 161 days. On the other hand, the shortest growing season (99 days) was recorded in Pol-e Dokhtar county. The simulation results showed that the highest grain yield was produced in the eastern half of the province, especially in Dorud county (7957 kg/ha) and the north of the province, including Borujerd (6286 kg/ha). On the other hand, Aligudarz and Aleshtar counties had the lowest rapeseed yield.

4. Discussion
The findings of this study showed that the central and eastern half of Lorestan province (specifically, Dorud county) had the highest rapeseed yield. Among the reasons for the high rapeseed yield in Dorud county can be attributed to the high rainfall (643 mm), the average favorable and cool air temperature (16.4 °C), and the long growth period (157 days) for photosynthesis and sufficient dry matter production. On the other hand, the counties of Khorramabad and Pol-e Dokhtar had a low average grain yield compared to other studied areas, which can be attributed to the inappropriate amount and distribution of seasonal rainfall on the one hand and the shorter growing season on the other hand, among the factors affecting the decline in rapeseed yield in these areas. The results of linear regression between grain yield and growing period length, average annual rainfall, and minimum and maximum temperatures also confirmed the above, showing that areas with high rainfall and long growing period had higher grain yield.

5. Conclusion
In general, considering the suitable climate of the counties of Dorud and Borujerd and the minimum and maximum temperatures that are favorable for canola growth, as well as the amount and distribution of rainfall during the canola growth period, the development of canola cultivation in the aforementioned areas is more suitable than in other areas of the province.

Author Contributions
All authors contributed equally to all aspects of this study and approved the final manuscript.

Data Availability Statement
Data available on request from the authors.

Acknowledgements
Not applicable.

Ethical Considerations
The authors declare that this research was conducted in accordance with ethical standards and research integrity principles.

Funding
This study was conducted as part of a Ph.D. dissertation at Lorestan University. The authors acknowledge the financial and institutional support provided by Lorestan University.

Conflict of Interest
The authors declare no conflict of interest.
Keywords
Rapeseed
WOFOST model
Lorestan province
Model performance assessment
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Journal of Geographical Studies of Mountainous Areas
Volume 7, Issue 2 - Serial Number 26
Summer
Spring 2026
Pages 23-42