پديد آورندگان :
فاتح، شاهرخ سازمان هواشناسي كشور - مركز ملي خشكسالي و مديريت بحران , رسولي، علي اكبر دانشگاه تبريز - دانشكده جغرافيا و برنامه ريزي - گروه آب و هواشناسي , ساري صراف، بهروز دانشگاه تبريز - گروه اقليم شناسي , كمالي، غلامعلي دانشگاه آزاد اسلامي واحد علوم و تحقيقات - گروه هواشناسي
كليدواژه :
طول فصل رشد , واحدهاي گرمايي طول فصل رشد , آستانه هاي دمايي , پهنه بندي اقليمي , ايران
چكيده فارسي :
شناخت و آگاهي از چگونگي تغيير فرآيندهاي كشاورزي مي تواند برنامهريزان بخش كشاورزي را در روند شناخت راهكارهاي مناسب براي كاهش خسارات احتمالي اين چالش ياري نمايد. چگونگي تغييرات فصل رشد محصولات كشاورزي از جمله گندم دركشور يكي ازمهمترين مقولههاي پژوهشي است كه بايد مورد بررسي قرارگيرد. در اين مطالعه، ضمن تعريف فصل رشد، چگونگي تغييرات آن در طول رشد گياه گندم به عنوان يكي از محصولات استراتژيك كشاورزي با روش هاي مختلف از جمله تجزيه و تحليل داده هاي آب و هوايي و با استناد به اندازه گيري هاي فنولوژيك گندم ديم استخراج خواهند شد. در بين عناصر اقليمي دما از اهميت خاصي برخوردار است و به اين دليل بررسي تاثيراتي كه دما در رشد و نمو موجودات بويژه گياهان مي گذارد، ضروري مي باشد. هدف كلي اين مقاله بررسي و پهنه بندي واحدهاي گرمايي طول فصل رشد گياه گندم بر اساس پايه دمايي صفر درجه سلسيوس در 27 ايستگاه سينوپتيك ايران در طول دوره آماري مشترك 30 ساله با استفاده از شاخص هاي دمايي طي سال هاي 2010-1981 بوده است. به اين منظور به منظور محاسبه واحدهاي گرمايي ابتدا طول فصل رشد براي آستانه دمائي صفر درجه سلسيوس بدست آمد و پس از محاسبه واحدهاي گرمايي نقشه پهنه بندي واحدهاي گرمايي در GIS تهيه شد. ميزان واحدهاي گرمايي طول فصل رشد در پايه دمايي صفر درجه سلسيوس از جنوب به شمال و از غرب به شرق كشور مي يابد.
چكيده لاتين :
Climate is a major environmental factor that controls all aspects of life. Among the climatic elements temperature is the important factor and because of this, study the effects of temperature on the growth of organisms, especially plants will be necessary. If temperature to be below the critical level of growth, plant growing stages will be stop and may hurt plant. The critical level temperature is different and dependent on the kind of plants. The majority of biological changes in plants is dependent on Growing Degree-days. In the present study, it has been achieved Growing Degree Days (GDD) Zoning with using temperature indicators. According to these factors, it has been determined capabilities and limitations of agricultural climate in different plant species adaption in country. Wheat is one of the strategic agricultural products of Iran. This variety of wheat has the best yield and quality in north-western provinces of country, including West and East Azerbaijan, Ardabil, Zanjan, Kordestan and Hamedan. Despite the fact that the mentioned region has the area of 17578000 acres or nearly 16.3% of the country area, the area under cultivation of winter wheat in these provinces consist about 40% of total wheat cultivating farms in the country or about 2411000 acres. This implies that the region is prone of cultivating wheat (and also other agricultural products) about 2.3 times more than other parts of country.
Another fact that verifies this is fraction of area under cultivation of wheat per total province area. Among 31 Iranian provinces, ranking of this statistic shows that all the provinces in selected area rank below 10, including first rank in country, Hamedan Province with 21.2% of its area under cultivation of wheat, Second rank Ardabil Province with 20.0%, rank 4 Kordestan province with 18.4%, rank 6 Zanjan provinces with 14.1% and finally, rank 9 and 10 East and West Azerbaijan provinces with 9.7% and 9.6% respectively.
Although the most important source of impact on yield of wheat, especially in dry farming, is adequate and timely precipitation, the climate change and global warming plays an undeniable role on long-term trends and attitudes toward choice of new places for building farms to answer the consistently increasing demand for this strategic product.
The trend in four phenological stages beside total Lenth of Crop Season (LCS) as a measure of intensity of the effect of climate is calculated in 27 stations in the region.
Materials and methods
For this research, it has been used daily temperature at 27 Synoptic Stations during 1981 to 2010 periods. For calculating heat units, it was used the thresholds of 5 and 10 ° C as the lower threshold and 30 and 35 C °for the upper thresholds. For determining of hit units, at first, the dates of starting and end of 5 and 10 C° temperatures were extracted and then heat units during the growing season was calculated from mean daily temperature minus the base temperature and zoning heat units maps in GIS were prepared.
Result and discussion
According to this research, the growing season length of 5 and 10 C° were divided into five categories in Iran. In the research, the areas of the country that Thermal Units based on 5 and 10 were homogeneous had taken in a group. Heat units in the base of 5 C° are divided into five groups, including 2000-2500, 2500-3000, 3000-3500, 3500-4000, 4000> (GDD) and for 10 C° are divided into four group including 500-1500, 1500-2500, 2500-3500, 3000>.(GDD).
Conclusion
Growing Season Degree-Days for the basis of 5 and 10 C° are declining from South to North and East to West in the country. The Heat Units amounts during the growing season at 5 C° are increased from South to North and West to East. These amounts are decreased from South to North for the base temperature 10 C° and are increasing from West to East. According to the obtained results, it can be suggested that in areas where the growing season is reducing, farmers by reducing crop yield and also products that have not been well face. That is better farmers used early growing plants until they got heat energy to supply in the plant during the growing season.
