پهنه بندي زماني و مكاني اراضي مستعد كشت پنبه( .Gossypium hirsutum L) با استفاده از روش تحليل سلسله مراتبي(مطالعه موردي استان خراسان جنوبي)

( Spatial and Temporal Zoning of Suitable Lands for Cotton (Gossypium hirsutum L) Cultivation using Analytical Hierarchy Process (Case study: South Khorasan Province

در بين عوامل مختلف تاثيرگذار در توليد محصولات كشاورزي، شرايط اقليمي از مهمترين متغيرهاي محيط طبيعي است. از سويي ديگر، اساس توسعه كشاورزي، آگاهي دقيق از ويژگي هاي محيطي در هر نقطه و اعمال مديريت ويژه مي باشد. پنبه (Gossypium hirsutum L.) به دليل داشتن ريشه هاي گسترده و نفوذپذير و همچنين دارا بودن قابليت تنظيم تعداد برگ و ميوه زماني كه گياه تحت شرايط تنش قرار مي گيرد و نيز داشتن دوره قوزه دهي قابل انعطاف از گياهان مناسب براي كشت در مناطق خشك و نيمه خشك محسوب مي شود. بر اين اساس، اين تحقيق به منظور ارزيابي شرايط اقليمي براي كشت پنبه در تاريخ هاي كشت مختلف در استان خراسان جنوبي در يك دوره آماري 25 ساله (1394-1374) صورت گرفت. بدين منظور، پانزده ايستگاه هواشناسي استان خراسان جنوبي انتخاب و به كمك محيط نرم افزاري GIS Arc مدل سازي و تحليل فضايي صورت گرفت. با بهره گيري از شرايط اقليمي مطلوب در هر مرحله از رشد پنبه، لايه هاي اطلاعاتي كلاس بندي و ارزش وزني هر كدام از عوامل مشخص گرديد. در نهايت، به منظور هم پوشاني لايه هاي اطلاعاتي با استفاده از روش هاي تصميم گيري چند معياره مبتني بر روش تحليل سلسله مراتبي (AHP)، نقشه هاي نهايي مربوط به هر تاريخ كشت از نيمه اول فروردين تا نيمه اول تير براساس عوامل اقليمي براي كشت پنبه در استان خراسان جنوبي تهيه گرديد. نتايج نشان داد كه نقش هر يك از عناصر اقليمي بارش و دما، متناسب با هر تاريخ كشت، در مناطق مختلف استان متفاوت بود و اهميت آن بيشتر از عوامل زميني بود و از بين همه تاريخ هاي كشت از فروردين ماه تا تيرماه، بهترين تاريخ كشت مربوط به نيمه اول و نيمه دوم ارديبهشت ماه بود، چون از نظر مساحت مناطق مناسب به ترتيب 56 و 68 درصد بيشترين مساحت را به خود اختصاص داده اند.

Introduction Climatic conditions are the most effectiveness than from the natural environment variables for agricultural production On the other hand the base of agriculture development، especially in semi-arid zone is the accurate knowledge of environmental characteristics and its management practices. Cotton (Gossypium hirsutum L.)، due to the extensive roots and permeability and the ability to set the number of leaves and fruits under water stress، is a suitable crop for planting in arid and semi-arid climates. South Khorasan Province is a dry، desert and mountainous region with post-semi-arid and semi-arid climates. South Khorasan province produces 34000tons of cotton annually with 13000 hectares of irrigated cotton lands and the second position in cotton production ranking in Iran. Materials and MethodsSouth Khorasan Province is located in the east of Iran with an area of 149،107 square kilometers and the geographical coordinates of 30 degrees and 31 minutes to 34 degrees and 53 minutes of northern latitudes and 57 degrees and 3 minutes to 57 degrees and 60 minutes of eastern longitude. This study was performed to evaluate the climatic conditions for the cultivation of cotton in the history of different cultures in South Khorasan province in a 25-year period (1990-2015). For this purpose، fifteen stations of South Khorasan province was chosen as target and modeling and spatial analysis was performed by Arc GIS. By using advantage of favorable climatic conditions at each stage of cotton growth، was prepared data layers of classification and weighting values for each of the zones. Eventually، in order to overlay layers using multi-criteria decision-making methods based on the Analytic Hierarchy Process (AHP)، the final maps was prepared for each date based on the climatic factors of the cotton cultivation date in South Khorasan. Results and DiscussionAccording to the results obtained from zonation of different cultivars، in the western and southern parts of the province، the suitable planting date will be from the first to second half of the April. This is while the planting date in the central and northern regions and some parts of the south of the province will continue from the first month of cultivate (March) to the first half of the second month until the first half of May. In the eastern parts of the province، suitable planting dates will continue from the second half of June to the first half of July. Considering the cotton ecological needs، if the plant cultivated in suitable planting date in different regions of the South Khorasan Province، there will be no growth inhibitory temperatures for this crop. The results of all cultivar maps indicate that among all planting dates from April to July، the best cultivation date was the first half to the second half of May، because they have the largest area in terms of area of suitable areas. The first half of July، due to lack of rainfall and temperature increase، is not a suitable time for flowering stage of cotton، because of it will be treated at a lower temperature when it is processed. Therefore، just with the reduction of the product. For cultivation of cotton in the first and second half of April the appropriate areas are western and southern regions of the province. ConclusionThe results was showed that the role of temperature and precipitation as climatic factors، were difficult for any cultivation date in different regions and cultures of all dates from April to July. The best planting date from the first half and the second half of May، because of، respectively، 84،680 and 103،100 square kilometer area of the right to have the largest area. For all climatic conditions also have an important loss condition.