Document Type : Research Paper
Authors
1 Department of Irrigation & Reclamation Engineering, Faculty of Agricultural Engineering and Technology, University of Tehran, Karaj, Iran
2 Department of Irrigation and Reclamation Engineering, College of Agricultural and Natural Resources, University of Tehran, Karaj, Iran.
Abstract
Keywords
Main Subjects
Canola (Brassica napus L.) plays a strategic role in global food security as one of the world’s most significant sources of edible and industrial vegetable oil, ranking second in consumption only to palm oil. The success of crop production, like canola, across diverse geographical regions is substantially contingent upon a thorough understanding of their climatic potentials. When determining the climatic potential of agricultural production areas, due attention must be paid to climatic hazards (climate extremes). This research investigates the projected impacts of future climate change on the vulnerability to climate-related constraints during the canola growth period within Golestan Province, Iran.
Daily meteorological observations, encompassing precipitation, minimum temperature, and maximum temperature, were procured from ten synoptic weather stations operating in the region. The thermal thresholds for the four principal phenological phases of canola—specifically germination, vegetative growth, reproductive development, and seed maturation—were rigorously established based on prior investigations. Following meticulous data quality assessment and the statistical imputation of any identified gaps, outputs from two representative global climate models (MPI-ESM1-2-LR and ACCESS-ESM-1-5), simulated under the intermediate Shared Socioeconomic Pathway (SSP2‑4.5) scenario, were downscaled for the near‑term future (2023–2053) utilizing the LARS‑WG statistical downscaling model. Subsequently, the phenological progression of canola through its four developmental stages was delineated for both the historical baseline period (1992–2022) and the projected future climate, employing a growing degree‑day (GDD) model. A suite of eight key agroclimatic indices was then formulated, and their temporal variations were quantified across both the baseline and future scenarios for each phenological phase. The agroclimatic indices defined in this study are: a) Number of dry days (precipitation < 2.0 mm) (Ndry), b) Number of heavy rainfall days (precipitation > 10 mm) (NHrain10), c) Number of frost days (minimum temperature ≤ 0°C) (NTmin0), d) Number of vernalization days (average temperature between 0°C and 5°C) (NTmean0-5), e) Number of heat stress days (maximum temperature > 30°C) (NTmax30), f) Total precipitation during the phenological stage (SUMrain), g) Average daily temperature during the phenological stage (AVETmea), h) Duration of the phenological stage (DurationDev). The risk (probability of occurrence) of agroclimatic indices within each of the four canola growth stages, was calculated for the baseline period and the future period (under two global climate models) across all stations.
Our findings revealed the LARS-WG model demonstrated greater success in reproducing daily precipitation compared to daily minimum and maximum temperatures for the baseline period. Also, it was detected a discernible trend towards increased annual precipitation in nine months and statistically significant warming across nearly all months for both minimum and maximum temperatures when compared to the baseline. Under the projected climate change scenario, a notable shortening of the canola emergence and vegetative phases is anticipated, while the reproductive and maturation periods are expected to lengthen. These temporal shifts are intrinsically linked to the projected directional changes in temperature (warming) and precipitation (drying trends) during these respective developmental periods. The results obtained from comparing the occurrence risk of indices between the baseline and future periods are as follows: a) The probability of frost occurrence is higher in the vegetative and reproductive stages of canola compared to other stages. In the future, the risk of frost occurrence is expected to decrease during the vegetative stage and increase during the reproductive stage. b) The probability of temperatures between 0 and 5 degrees Celsius is higher in the vegetative and reproductive stages of canola than in other stages. The likelihood of this temperature range occurring is expected to decrease in the future. c) The highest probability of temperatures exceeding 30 degrees Celsius is associated with the maturity stage. However, there is also a possibility of heat stress occurring during the germination and reproductive stages. Overall, the probability of heat stress is projected to decrease across all phenological stages in the future. d) The probability of no precipitation (dryness) is highest during the germination stage compared to other stages. It is anticipated that the likelihood of dryness in this stage will be lower in the future compared to the baseline period. In other phenological stages, the probability of no precipitation is expected to increase in the future. e) The probability of heavy rainfall is projected to decrease during the germination stage in the future. However, the likelihood of heavy rainfall is expected to increase in other stages in the future.
The analysis highlights an augmented risk of frost damage during the critical reproductive stage, a diminished likelihood of satisfying the necessary vernalization (chilling) requirements in the vegetative phase, alongside an elevated probability of both extreme drought conditions and intense precipitation events throughout the entire canola phenological cycle. These findings underscore the critical need for adaptive agricultural strategies to mitigate the adverse impacts of projected climate change and ensure food security in the study area.
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Conceptualization, Javad Bazrafshan; methodology, Javad Bazrafshan; software, Javad Bazrafshan and Seyyedeh Fatemeh Arab; formal analysis, Javad Bazrafshan and Seyyedeh Fatemeh Arab; data curation, Seyyedeh Fatemeh Arab; writing—original draft preparation, Javad Bazrafshan; writing—review and editing, Javad Bazrafshan; visualization, Seyyedeh Fatemeh Arab. All authors have read and agreed to the published version of the manuscript.
Statement: Not Applicable.
Data available on request from the authors.
The authors would like to thank Iran Meteorological Organization for supporting the data needed in the present study.
The authors avoided data fabrication, falsification, and plagiarism, and any form of misconduct.
The authors declare no conflict of interest.
)