Effect of climate change on growth and seed yield of canola (Brassica napus L.) in Dehgolan plain of Kurdistan province in Iran-using the DSSAT program

The crisis of water sources limitation has signified the necessity of irrigation management of canola crop unavoidable. This issue is especially critical in the context of climate change, which is accompanied by changes in precipitation amount and patterns as well astemperature flucatations. The time-consuming and costly nature of field research and the spatial and temporal dependence of the results have caused crop growth modelling to be considered as an effective and acceptable technique in decision support systems under climate change conditions. In this regard, the DSSAT program is one of the most successful programs available for simulating the growth and development of crops. In this study simulation program for plant growth and development was used to predict growth and seed yield of canola in Dehgolan in Kurdistan province of Iran.

This study consisted of two phases; field and simulation studies. Statistical Downscaling Model (SDSM) was used to simulate climate data and forecast climate changes in the future. For the future climate, the set of CanESM scenarios including; RCP2.6, RCP4.5 and RCP8.5 scenarios, presented by the Canadian Earth System Modeling Center, were used. Then, the changes in the growth and yield of canola under the mentioned scenarios were studied in the four periods of 2021-2040, 2041-2060, 2061-2080, and 2081-2100 using the CSM-CROPGRO-Canola model in the DSSAT program. In field studies, two field experiments were carried out to calibrate and validate the output of the model in the research farm of the Kurdistan University in Dehgolan 2016-2017 and 2017-2018 cropping seasons.

The results of validation for weather and growth models showed that the models had sufficient accuracy to simulate climate variables and also the growth of canola. The simulation results illustrated that the growth characteristics of canola were affected by the negative effects of climate change under all scenarios and different time periods, therefore, the plant traits in various climate change scenarios were low when compared to the baseline cropping season (2018-2019). In general, the results of the model showed that the maximum negative effects of climate change on canola growth was in the RCP8.5 scenario and the minimum in the RCP2.6 scenario. The adverse effects of climate change were accelerated by time, especially in the RCP8.5 scenario.

The results of this study showed that the future climate change will have a negative effect on the growth and yield of canola that depends on the scenario and time period, the seed yield will decrease from 0.3% to 37.58% as compared with the current conditions. Therefore, to mitigate climate change impact on agricultural ecosystems necessary management measures including development of suitable canola cultivars and agronomic mangament package should be taken into consideration for adaptation to the changing climate in future.