@article { author = {Abbasi Alikamar, Reza and Nassiri Mahallati, Mahdi and Koocheki, Alireza}, title = {Evaluation of Temperature Changes and Its Impacts on Seed Filling Period and Grain Yield of Wheat (Triticum aestivum L.) in Different Regions of Iran (1992-2012)}, journal = {Journal Of Agroecology}, volume = {12}, number = {2}, pages = {319-343}, year = {2020}, publisher = {Ferdowsi University of Mashhad}, issn = {2008-7713}, eissn = {2423-4281}, doi = {10.22067/jag.v12i2.58737}, abstract = {IntroductionIt is accepted that the global annual average temperature has been increased during recent decades. The climate of Iran is also affected by this global warming. Some studies indicated the increasing of mean annual temperature of Iran between 3.5-4.5○C by 2050. Crop phenology is directly related to temperature, so climate change could significantly change the phenology and yield of crops. Modelling phenology is a way to simulate the timing of phenological stages based on climatic factors. Amongst models, WOFOST is known as a powerful model for simulation of phenological stages and yield of wheat. In this study climate warming of Iran was evidenced. Based on this fact, trends of potential grain yield and time of flowering and maturity of wheat were studied in different climatic zones of Iran during 1992-2012. It is expected that understanding the thermal induced of phenological changes, can lead us to better field management decision making.Materials and MethodsWeather data of 18 cities from 4 climatic zones of Iran (northern warm and humid (Zone 1), southern warm and dry (Zone 2), temperate (Zone 3) and cold and high elevation (Zone 4)) were analyzed during 1992-2012 and the long-term trends of air temperature were detected by linear regression. The crop growth simulation model WOFOST, was used to simulate the time of flowering and maturity and also the potential grain yield of winter wheat. Calibration and validation of model was conducted in 4 selected cities from each zone using statistical measures. The consequences of temperature on duration of grain filling period and also yield of wheat were determined.Results and DiscussionResults indicated that the mean annual air temperature was significantly increased in all cities during 1992-2012. The highest increasing rate (regression line slope) belonged to Ardabil (0.159○C.y-1) and the lowest rate was observed in Pars Abad Moghan (0.06○C.y-1). Validation of WOFOST in 4 selected cities from each climatic zone, showed the perfect ability of model in simulating the flowering and maturity time of wheat. Regression analysis showed that the grain filling period was increased in accordance with temperature rise in zone 1 and 4 whereas it was shortened in zone 2 and 3. Grain yield showed the same trends predicted for grain filling period in different climates. Slop of linear regression between temperature and yield was significant except in Gorgan (Zone 1). In all cities the relation between grain filling period and yield was direct and positive.ConclusionAlthough temperature has increased in all climatic zones of Iran, flowering and maturity time and grain yield of wheat has showed different responses. There was a nonsignificant slope of regression line in the north humid climate, which means that the humidity of northern part of Iran (south of Caspian Sea) enhanced stability for this area. Annual mean temperature in southern warm and dry zone of Iran ranged between 24.3-27.9 ○C that could be stressful for wheat, and hence resulted in shorter grain filling period and less grain yield. It seems that in temperate zones (such as Mashhad) increasing temperature caused yield reduction due to faster GDD accumulation and lack of time to complete remobilization of photosynthetic materials. On the other hand, in cold areas increasing temperature could reduce the risk of cold stress in flowering time, resulting in longer grain filling period and higher grain yield. According to WOFOST simulation results, during 20 years study (1992-2012), mean potential yield of wheat increased 6.25 and 11.42 percent in northern warm and humid (Zone 1) and cold and high elevation (Zone 4), respectively and decreased 12.17 and 13.11 percent in southern warm and dry (Zone 2) and temperate (Zone 3), respectively. Total mean potential yield of wheat, by consideration of proportion of each zone in total wheat production of Iran, showed reduction of 1.8% and 3.28% during 1992-2001 period (10 years) and 1992-2012 period (20 years), respectively.           }, keywords = {Climate change,Global warming,Regression,simulation,WOFOST}, title_fa = {بررسی روند تغییرات دمایی و اثرات آن بر طول دوره پر شدن دانه و پتانسیل عملکرد گندم (Triticum aestivum L.) در مناطق مختلف ایران در طی یک دوره 20 ساله (91-1371}, abstract_fa = {میانگین دمای سطحی زمین در طی 30 سال گذشته در طی هر دهه 2/0 درجه سانتی‌گراد افزایش داشته است. ایران نیز از این گرمایش جهانی به دور نبوده و اثرات آن در نقاط مختلف کشور مشهود می‌باشد. این تغییرات دما اثرات زیادی بر دوره‌های رشدگیاهان دارد و به‌ تبع آن تولید گیاهان زراعی را نیز تحت تأثیر قرار می‌دهد. در این پژوهش روند تغییرات دمای 18 شهر از چهار ناحیه اقلیمی (خزری، گرم، معتدل و سردسیر) در طی 20 سال گذشته (91- 1371) مورد مطالعه قرار گرفت و با استفاده از مدل شبیه‌سازی WOFOST مراحل گل‌دهی و رسیدگی گندم آبی (Triticum aestivum L.) در هر منطقه مشخص شد. سپس تغییرات مراحل گل‌دهی و رسیدگی و همچنین عملکرد گندم و رابطه آن‌ها با دما در هر ناحیه بررسی شد. نتایج نشان داد که در طی سال‌های مورد مطالعه، در تمامی 18 شهر کشور، دمای میانگین سالانه افزایش یافت که در آن اردبیل بیشترین شدت افزایش دما (159/0 درجه سانتی‌گراد به‌ازای هر سال) و پارس‌آباد مغان کمترین شدت افزایش دما (066/0 درجه سانتی‌گراد به‌ازای هر سال) را نشان داد. واسنجی و تغییرات پارامترهای مدل WOFOST بر اساس داده‌های واقعی و صحت‌سنجی مدل با RMSE% و آزمون شیب خط رگرسیون برای شهرهای منتخب هر ناحیه اقلیمی انجام شد. نتایج نشان داد که این مدل با دقت بالایی قادر به تخمین مراحل گل‌دهی و رسیدگی گندم بود. در مناطق گرم و مرطوب خزری افزایش دمای میانگین سالانه، با شدت کمی طول دوره پر شدن و عملکرد دانه را افزایش داده که احتمالاً به‌دلیل اثرات تعدیلی رطوبت هوا در این مناطق بوده است. امّا در مناطق گرم و خشک جنوب و مرکز ایران افزایش دما به‌تدریج با ایجاد تنش در دوره رسیدگی دانه منجر به کاهش طول دوره پر شدن دانه و کاهش عملکرد گندم شده است. در مناطق معتدل نیز با افزایش دما، کاهش طول دوره پر شدن و عملکرد دانه گندم مشهود بود. با افزایش دمای میانگین سالانه در مناطق سردسیر، طول دوره پر شدن دانه افزایش یافته که دلیل آن احتمالاً عدم برخورد ابتدای دوره زایشی با سرمای خسارت‌زا بوده است و قرار گرفتن دوره پر شدن دانه در محدوده دمایی مناسب در این نواحی منجر به افزایش عملکرد شده است. میانگین عملکرد پتانسیل گندم با در نظر گرفتن سهم شهرهای مورد مطالعه از تولید کل کشور در طی یک دهه (81-1371) به‌میزان 8/1% و در طی دو دهه (91- 1371) به‌میزان 28/3 % کاهش داشته است.}, keywords_fa = {تغییراقلیم,رگرسیون,شبیه‌سازی,گرمایش جهانی,WOFOST}, url = {https://agry.um.ac.ir/article_37499.html}, eprint = {https://agry.um.ac.ir/article_37499_b14611417fbf7350dd278ce3d38b2b1b.pdf} }