Adaptation strategies to lessen negative impact of climate change on grain maize under hot climatic conditions: A model-based assessment

Rise in temperature, particularly in warmer areas, could have a negative effect on maize productivity. However, careful management practices could reduce the effects of high temperatures by altering the sowing dates and type of cultivar. The current study applied APSIM (The Agricultural Production Systems sIMulator) crop model to investigate the interaction of sowing date and cultivar when dealing with climate change and high temperatures at nine locations in Khuzestan province, in southwestern Iran. Daily climatic data for the baseline period of 1980-2010 was obtained from the Meteorological Organization of Iran. Projections of the future climate of Khuzestan was done in Miroc5 (Model for Interdisciplinary Research on Climate) GCM (Global Climate Model) for 2040-2070 under two RCPs (Representative Concentration Pathways) (RCP4.5 and RCP8.5) using the methodology developed by AgMIP (The Agricultural Model Intercomparison and Improvement Project). The high risk window for extreme temperature was calculated as the number of days having a maximum temperature of over 36 °C (Tmax > 36 °C) during pre-flowering and flowering. Results indicated that for mid-future (2050), the average maize grain yield in almost all study areas except Masjed Soleyman decreased in comparison to baseline at −13.7% and −22.8% for RCP4.5 and RCP8.5, respectively mainly because the length of the high-risk window for extreme temperature had expanded from 18.8 to 26.3 days for RCP4.5 and RCP8.5, respectively, compared to baseline. Most farmers have not realized that they are currently sowing maize during a high-risk window for extreme temperatures (Tmax > 36 °C) in some seasons. If farmers do not apply adaptive options for their regions (most promising sowing date × cultivar), the probability of economical grain yield will be less than 50% for an average economical grain yield of 8.9 t ha−1. The current findings support the hypothesis that climate change by the middle of the 21st century will not be beneficial for maize agroecosystems in hot areas like Khuzestan province unless the best sowing date × cultivar is applied for both winter and summer sowing dates.