پديد آورندگان :
عزيزي، قاسم دانشگاه تهران - دانشكده جغرافيا - گروه جغرافياي طبيعي - دانشيار , كريمي، مصطفي دانشگاه تهران - دانشكده جغرافيا - گروه جغرافياي طبيعي - دانشيار , رستمي، هما دانشگاه تهران - دانشكده جغرافيا , ملكي، سحر دانشگاه تهران - دانشكده جغرافيا
كليدواژه :
آب و هواي ديرينه , اهلي شدن , تغييرات فراژنتيكي , گندم
چكيده فارسي :
تغييرات اقليمي همواره از راه ايجاد تغيير در مؤلفه‌هاي محيطي، اثرات بسياري بر انقراض ، انطباق و يا سازگاري گياهان و جانوران داشته است. نتايج به‌دست‌آمده از تحقيقات انجام‌شده بر چگونگي اهلي شدن گندم و تغييرات ژنتيكي آن نشان‌دهنده وجود ارتباط ميان اين تغييرات شرايط آب و هواي گذشته و تغييرات ژنتيكي گندم مي‌باشد. در بيش از 12500 سال قبل، گندم براي سازگاري با شرايط اقليمي سردتر و داراي بادهاي شديدتر با تشكيل ياخته‌هاي كوچك و تغيير در اندازه و شكل دانه‌ها و كوتاه و ضخيم‌تر نمودن ساقه به نوعي سازگاري در برابر تغييرات ناگهاني اقليم دست يافت. تغيير اقليم انسان منشأ كنوني و گرم‌تر شدن شرايط اقليمي در عرض‌هاي پايين و مياني در كاهش ميزان باروري، تغيير در اندازه، شكل و كيفيت دانه‌هاي گياهان و به‌ويژه غلات جهت رسيدن به سازگاري با شرايط اقليمي حاضر مؤثر است. با انتقال كمربندهاي كشاورزي به عرض هاي بالا اگرچه شرايط دمايي مطلوبي جهت رشد گندم وجود خواهد داشت اما عواملي همچون رطوبت زياد، فقير بودن خاك اين عرض‌ها ازلحاظ مواد آلي و كمضخامت بودن خاك از مهم‌ترين مسائلي است كه كشت گندم را محدود ميكند ، همچنين احتمال بروز انواع آفات و بيماري‌هاي قارچي غلات افزايش خواهديافت. در اين پژوهش با استفاده از مرور مقالات معتبر در سطح ملي و بين المللي سعي بر آن شد تا با توجه به تغيير اقليم در عصر حاضر و بحث امنيت غذايي، رشد و سازگاري گونه هاي گندم در شرايط اقليمي متفاوت درگذشته مورد بررسي قرار گيرد تا بتوان با توجه به ميزان تغييرات بارش و دما در آينده گونه هاي داراي سازگاري بالاتر را جهت توليد، انتخاب و مكانهاي مناسب را جهت كاشت اين محصول معرفي نمود.
چكيده لاتين :
Introduction
The results from the previous studies show that there was a relation between domestication of
wheat, genetic variation and paleo-climatic conditions. Wheat has been adapted to colder and severe
winds climatic conditions with formation of small cell and changing in size and shape of seeds
together with shortening and thickening of stem, approximately 12,500 years ago. The studies
showed that wheat crop was planted in the Fertile Crescent region for the first time and then spread
out in other geographical areas. Structural and behavioral characters of wheat crop were made in
different climatic periods so that it was disappeared in some geographical areas and adapted to
others with the environment. As extent of plant communities were changed during different climatic
periods, some crops dead and some of them were adapted to the new conditions. To understand how
much climate change has affected on domestication and evolution of wheat crop and the crop how
much will be able to adapt to future climate change, it needs to know about the domestication and
evolution trend of wheat in different climatic periods. By identifying the relationship between
climate and wheat morphology and genetic, it is possible to predict the future changes of the
strategic plant under different scenarios of climate change. The highly adapted species can be
selected on the basis of precipitation and temperature changes in the future. In addition, the suitable
regions can be introduced to plant the crop.
Materials and Methods
In this study, about 80 national and international papers in the field of wheat genetic variations have
been studied since its inception of Gramineae family. The effects of climate changes on different
species of wheat were investigated in various periods as well. With regards to the growth and
development together with the adaptation of the crop in different regions and climates in the past,
the suitable climate as well as location was detected to plant in the future.
Discussion and Results
Gramineae family has been evolved during the Cretaceous period 55 million years ago. However,
phytolithes founding in dinosaur fossils showed that the plants have existed 66 million years ago
(Payprnv, 2005). Cretaceous is the third period of the Mesozoic era after Triassic and Jurassic in
which occurred 145 to 65 million years ago and lasted 70 million years of the Cenozoic is the
longest period. The area of broadleaf forest, grasses species and Gramineae family increased in
North Africa and the Fertile Crescent in 110,000 to 116,000 years ago (Underhill et al., 2001). Wild
Einkorn grains found in the Fertile Crescent has the precedence more than 12,500 years (Ren
plentiful, 1979), but the grains of the domesticated type discovered in archaeological sites in
Greece, Cyprus and Balkans have the precedence of 9500 years old. Einkorn wheat was very
important for early farmers in Central Europe (7000 years ago). The genetic studies on Einkorn divided into 18 basins and most of the basins related to the northern and north-eastern areas which
are located in the uplift zone recorded high tectonic activities in most of the measured data.
Moreover, the basins have been divided into five levels according to the rate of their tectonic
activities; level 1 indicates the highest rate of activities and level 5 indicates the lowest.
Conclusions
After measuring all the indexes, the active tectonic index (lat) was measured for all the study area in
order to come up with an overall conclusion. This index also, confirmed other data and observations
as expected. A number of 6 catchments out of 18, all of which related to the northern and north
eastern areas, revealed the highest rate of tectonic activities, and their activity index was 1. A
number of 11 catchments revealed medium activity, and they were mostly related to the central and
southern areas of the study area; and only 1 catchment revealed the lowest tectonic activity which
was related to the most southern study area. Totally, according to the data collected from the three
catchment areas which were investigated in this study, the highest rate of tectonic activity is
recorded in Hablerood catchment area and the lowest rate is recorded in Eivanaki (Galooshoot)
catchment area, and Jajrood catchment area has revealed a medium rate of tectonic activities. The
results showed that in catchments affected by the main faults of the area such as Mosha, Emamzade
Davood and Porkan faults in the northern area and Hesarbon, Eivanaki and Garmsar faults in the
central and southern area, high tectonic activities were recorded which were also confirmed by field
observations.
