نوع مقاله : مقالات پژوهشی
نویسندگان
1 دانشگاه شاهرود
2 دانشگاه شهید چمران اهواز
3 مرکز تحقیقات کشاورزی و منابع طبیعی خوزستان
4 دانشگاه تهران
چکیده
در این مطالعه راهکارهای سازگاری گندم با تغییر اقلیم، توسط مدل گیاهی ارزیابی شده CERES-Wheat برای شرایط آب و هوایی شهرستان اهواز مورد بررسی قرار گرفت. بدین منظور سناریوهای تغییر اقلیم برای دو دوره آتی 2045-2015 و 20100-2070 با استفاده از 13 مدل GCM تحت دو سناریوی انتشار گازهای گلخانه ای A2 و B1 با ریسک 10/0 تولید شد. نتایج مقایسه عملکرد در شرایط تغییر اقلیم با دوره مبنا (2010-1980) نشان داد، با قبول ریسک 10/0، عملکرد در دوره های 2045-2015 و 2100-2070 به ترتیب حدود 4 و 15 کاهش می یابد. برای سازگاری با تغییر اقلیم، 4 راهکار به زراعی (تغییر تاریخ کشت، تغییر مقدار نیتروژن مصرفی، تغییر رژیم آبیاری و اصلاح واریته گندم) مورد بررسی قرار گرفت و نتیجه گرفته شد که تاریخ کشت های 30 آبان ماه (تاریخ کشت نرمال دوره مبنا) و 20 آذرماه به ترتیب برای دوره های 2045-2015 و دوره 2100-2070، مناسبترین تاریخ کشت می باشند. ارقام دیررس متحمل به گرما عملکرد بالاتری را نسبت به ارقام میان رس و زودرس داشتند، که نشان می دهد اصلاح واریته گیاهی راهکاری مناسب برای سازگاری با تغییر اقلیم می باشد. همچنین مشخص گردید که در دوره های آتی مقدار مصرف نیتروژن به میزان 20 درصد کاهش خواهد یافت. افزایش و کاهش یک نوبت آبیاری (40 میلیمتر) نسبت به رژیم آبیاری دوره مبنا، بهترین نتایج عملکرد را به ترتیب برای دوره 2045-2015 و 2100-2070 به همراه داشت. اما از نظر بهره وری مصرف آب (WPI)، کاهش دو نوبت آبیاری نسبت به رژیم آبیاری دوره مبنا، بهترین رژیم آبیاری برای هر دو دوره آتی معرفی شد.
کلیدواژهها
عنوان مقاله [English]
Adaptation Strategies of Wheat to Climate Change (Case Study: Ahvaz Region)
نویسندگان [English]
- M. Delghandi 1
- S. Broomandnasab 2
- B. Andarzian 3
- A.R. Massah-Bovani 4
1 Shahrood University
2 ShahidChamran University of Ahwaz
3 Assistant Professor and Lecuture
4 Tehran University
چکیده [English]
Introduction In recent years human activities induced increases in atmospheric carbon dioxide (CO2). Increases in [CO2] caused global warming and Climate change. Climate change is anticipated to cause negative and adverse impacts on agricultural systems throughout the world. Higher temperatures are expected to lead to a host of problems. On the other hand, increasing of [CO2] anticipated causing positive impacts on crop yield. Considering the socio-economic importance of agriculture for food security, it is essential to undertake assessments of how future climate change could affect crop yields, so as to provide necessary information to implement appropriate adaptation strategies. In this perspective, the aim of this study was to assess potential climate change impacts and on production for one of the most important varieties of wheat (chamran) in Khouzestan plain and provide directions for possible adaptation strategies.
Materials and Methods: For this study, The Ahvaz region located in the Khuzestan province of Iran was selected.
Ahvaz has a desert climate with long, very hot summers and mild, short winters. At first, thirteen GCM models and two greenhouse gases emission (GHG) scenarios (A2 and B1) was selected for determination of climate change scenarios. ∆P and ∆T parameters at monthly scale were calculated for each GCM model under each GHG emissions scenario by following equation:
Where ∆P, ∆T are long term (thirty years) precipitation and temperature differences between baseline and future period, respectively. average future GCM temperature (2015-2044) for each month, , average baseline period GCM temperature (1971-2000) for each month, , average future GCM precipitation for each month, , average baseline period GCM temperature (1971-2000) for each month and i is index of month. Using calculated ∆Ps for each month via AOGCM models and Beta distribution, Cumulative probability distribution function (CDF) determined for generated ∆Ps. ∆P was derived for risk level 0.10 from CDF. Using the measured precipitation for the 30 years baseline period (1971-2000) and LARS-WG model, daily precipitation time series under risk level 0.10 were generated for future periods (2015-2045 and 2070-2100). Mentioned process in above was performed for temperature. Afterwards, wheat growth was simulated during future and baseline periods using DSSAT, CERES-Wheat model. DSSAT, CERES4.5 is a model based on the crop growth module in which crop growth and development are controlled by phenological development processes. The DSSAT model contains the soil water, soil dynamic, soil temperature, soil nitrogen and carbon, individual plant growth module and crop management module (including planting, harvesting, irrigation, fertilizer and residue modules). This model is not only used to simulate the crop yield, but also to explore the effects of climate change on agricultural productivity and irrigated water. For model validation, field data from different years of observations were used in this study. Experimental data for the simulation were collected at the experimental farm of the Khuzestan Agriculture and Natural Resources Research Center (KANRC), located at Ahwaz in south western Iran.
Results and Discussion: Results showed that wheat growth season was shortened under climate change, especially during 2070-2100 periods. Daily evapotranspiration increased and cumulative evapotranspiration decreased due to increasing daily temperatures and shortening of growth season, respectively. Comparing the wheat yield under climate change with base period based on the considered risk value (0.10) showed that wheat yield in 2015-2045 and 2070-2100 was decreased about 4 and 15 percent, respectively. Four adaptation strategies were assessed (shifting in the planting date, changing the amount of nitrogenous fertilizer, irrigation regime and breeding strategies) in response to climate change. Results indicated that Nov, 21 and Dec, 11 are the best planting dates for 2015-2045 and 2070-2100, respectively. The late season varieties with heat-tolerant characteristic had higher yield in comparison with short and normal season varieties. It indicated that breeding strategy was an appropriate adaptation under climate change. It was also found that the amount of nitrogen application will be reduced by 20 percent in future periods. The increase and decease of one irrigation application (40mm) to irrigation regime of base period resulted in maximum yield for 2015-2045 and 2070-2100, respectively. But, reduction of two irrigation application (80mm) resulted in maximum water productivity (WPI).
Conclusions In the present study, four adaptation strategies of wheat (shifting in the planting date, changing the amount of nitrogenous fertilizer, irrigation regime and breeding strategies) under climate change in Ahvaz region were investigated. Result showed that Nov, 21 and Dec, 11 were the best planting dates for 2015-2045 and 2070-2100, respectively. The late season varieties with heat-tolerant characteristic had higher yield in comparison with short and normal season varieties. It indicated that breeding strategy was an appropriate adaptation strategy under climate change. It was also found that the amount of nitrogen application will be reduced by 20 percent in future periods. The increase and decease of one irrigation application (40mm) to irrigation regime of base period resulted in maximum yield for 2015-2045 and 2070-2100, respectively.
کلیدواژهها [English]
- Climate change
- wheat
- Adaptation Strategies
- Crop Model
- scenario
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