شبیه‌سازی عملکرد دانه و کارایی مصرف آب در ارقام غالب ذرت تحت شرایط محدودیت آب و تغییر اقلیم

به‌منظور شبیه سازی عملکرد و کارایی مصرف آب در ارقام ذرت آزمایشی تحت شرایط تغییر اقلیم و محدودیت آب در استان خوزستان (مناطق اهواز، ایذه، دزفول و بستان) طراحی شد. اقلیم آینده (2070-2040) در این مناطق با استفاده از مدل گردش عمومی miroc5، تحت سناریوی اقلیمی rcp4.5 و روشagmip  پیش بینی شد. همچنین از مدل apsim برای شبیه سازی رشد و نمو گیاه ذرت در دوره گذشته (2010-1980) و آینده (2070-2040) استفاده گردید. نتایج نشان داد که به‌طور متوسط عملکرد دانه و کارایی مصرف آب ذرت در استان خوزستان در آینده نسبت به گذشته به‌ترتیب 2 و 5.7 درصد کاهش و میانگین دما در طول فصل رشد و تبخیر و تعرق 12.6+ و 0.9+ درصد افزایش خواهد داشت. به‌علاوه نتایج نشان داد که اگر کشاورزان یک آبیاری مناسب (آبیاری 10 دور) به‌کار ببرند، این موضوع باعث افزایش کارایی مصرف آب (42 درصد) و کاهش تبخیر و تعرق (3.8 درصد) خواهد شد. این سطح بهینه آبیاری در دوره آینده به‌همراه یک رقم دیررس (سینگل کراس 704) می تواند بهترین نتیجه را در استان خوزستان از نظر عملکرد دانه (7999.26 کیلوگرم در هکتار) و کارایی مصرف آب (16.94 کیلوگرم بر میلی‌متر در هکتار) داشته باشد.

Simulating Grain Yield and Water Use Efficiency in Dominant Maize Cultivars under Water Limited a Climate Change Conditions

Introduction Today, rapid population growth and economic development have increased demand for food, and climate change has affected food security worldwide. Climate change processes, including increasing the atmospheric carbon dioxide concentration, rising temperature, and fluctuation of precipitation, could directly affect agricultural products. Climate change also causes drought, which indirectly influences agricultural systems as water is the most important for grain yield and its quality. Arid and semiarid regions are limited in terms of water resources and they are the most fragile regions faced with drought caused by climate change. Khuzestan province is one of the hot and arid regions in Iran which its agricultural crops (especially maize) are very sensitive to climate change. Irrigation schedules and various cultivars can be considered as the adaptation strategies according to the climate change conditions. In agricultural ecosystems, water consumption should be reduced, and grain yield should be increased as much as possible. Optimizing water consumption by improving water use efficiency (WUE) is essential for achieving agricultural sustainability in arid and semiarid regions. Accordingly, modelling approach has been considered as a timesaving and lowcost way to study the effects of climate change and different treatments. The current study was conducted to investigate the effects of different irrigation management practices on maize grain yield and WUE under climate change conditions in order to optimize water consumption and WUE by using modeling approach. Material and Methods The current study was carried out in several locations of Khuzestan province, including Dezful, Izeh, Bostan, and Ahwaz. The longterm climatic data of the studied locations were collected from the Iran Meteorological Organization. These data included minimum and maximum temperatures (°C), rainfall (mm), and solar radiation (MJ m2) from 1980 to 2010. Angstrom equation was used for calculating the radiation based on sunshine hours. The climatic data were modified using WeatherMan software embedded in the DSSAT package. The future climate of Khuzestan province (20402070) was predicted by the MIROC5 general circulation model under the RCP4.5 climate scenario and using AgMIP methodology. According to the previous studies, the MIROC5 climatic model showed the highest accuracy in predicting the future climatic data of Khuzestan province. Two adaptation strategies, including cultivar and irrigation regime, were considered to mitigate the negative effects of climate change. The cultivars consisted of SC704 (latematurity) and SC206 (midmaturity), which had the highest area under cultivation in Khuzestan province. Irrigation regimes included three levels: 12time irrigation (as farmers’ common practice), 10–time irrigation, and 14time irrigation per growing season. Results and Discussion The results of the current study indicated that climate change had negative effects on maize grain yield as well as positive effects on average temperature during the growing season, evapotranspiration, and corn water use efficiency across the whole province. The results showed that the average grain yield and corn WUE in Khuzestan province in 2050 under the RCP4.5 scenario was 2% and 5.7%, respectively, compared to the baseline. In addition, mean temperature during the growing season and evaporation and transpiration increased by +12.6% and + 0.9% compared to the baseline. The results also showed that with the application of an optimal amount of irrigation regime (10time irrigation), an increase in WUE and decrease in evapotranspiration were observed, which resulted in acceptable grain yield. Results also portrayed that applying the optimal irrigation level (10time) along with a late maturity cultivar (SC704) showed the best performance in terms of grain yield (9433.9 kgha1) and WUE (19.57 kgha1 mm1) in the province Khuzestan. Conclusion The results illustrated that by 2050, the average grain yield and WUE were reduced compared to the baseline period. However, the mean temperature and evapotranspiration over the growing season were increased. Totally, the results of the current study revealed that an optimal irrigation level 10 and suitable cultivar SC704 could mitigate the negative impacts of climate change on maize in the agroecosystems of Khuzestan province.