İklim değişiminin buğday verimine etkilerinin incelenmesi: Kırklareli örneği

Abstract

The Thrace Region is located in The European partof the northwestern Turkey, which is responsible fora considerable portion of rice, sunflower and winterwheat productions of Turkey. Winter wheat (Triti- cum Aestivum L.) production rate in Thrace is gen- erally higher than that in the rest of Turkey. Howev- er, there is not enough qualified study on the effectsof drought and possible climate change on the re- gion’s agriculture. The dynamics and complexstructure of the plant growth are under the influenceof many factors which are out of human control.Meteorological parameters are the dominant onesamong these factors. Hence, reliable research stud- ies are to be conducted from the agricultural mete- orological viewpoint. Using crop growth simulationmodels, possible effects of the variations in plant,soil and atmosphere on wheat development and yieldcan be estimated. In this study, the CERES-Wheatcrop growth simulation model have been used forwheat during the years between 1975 and 2005 totake a first step for filling the gaps in the desireddrought related research in the Kırklareli City, inwhich the winter wheat production is popular. Atfirst, the average growing season have been deter- mined by considering long term phenological data(3 November-22 July). Afterwards, the associatedsoil-and crop parameters have been supplied intothe model database as well as the calculated dailyaverage meteorological data (daily totals for precip- itation). Average wheat grain yield was calculatedas 2827 kg/ha by the model with an relative error of3.1%. Model sensitivities to temperature, precipita- tion, global radiation and $CO _2$ have been done byconsidering single and combined variations. The(Rg30%; CO2x4) combined application gave thehighest yield increase response as 67.1%, where theopposite output was a 63.1% decrease for the(T+5;P-40%) application. Another step was the in- vestigation of the development and yield reactions ofthe crop to the IPCC A2 scenarios from 2071 to2100. To achieve this, model database used dailyoutput from the RegCm3 Regional Climate Model byconsidering the associated field coordinates. Themodel showed a 9% increase in winter wheat grainyields during the mentioned time interval. It hasbeen determined that the winter wheat yield wassensitive especially to variations in T and CO2.Thisstudy represents a part of the PhD named “Deter- mination of the Agrometeorological Properties ofthe Thrace Region”, in which additional cities(Edirne and Tekirdağ) have been investigated fromthe point of wheat production.30% yield increasehas been simulated for Edirne, while a 13% de- crease was expected for Tekirdağ during the aver- aged 2071-2100 growing period. Rice productionhas been also estimated for Edirne with a decreaseof 53%. RegCm3 data were also arranged andadapted into CERES meteorology files to enablemodel runs for the hottest and driest growing sea- sons for the 2071-2100 interval. Moreover; threedrought indices, namely the percentage of normal, zscore and standardized precipitation indices havebeen calculated and interpreted for seasonal fieldcrops (wheat, rice and sunflower) and forests (pine,oak and beech) during the years between 1975 and2005 to take a first step for filling the gaps in thedesired drought related research in the region. Ingeneral, dry periods were determined with low se- verities and continuities. Growing Degree Day(GDD) and vernalization calculations for field cropshave been also applied. Among the average growingseasons in Kırklareli, the winter wheat collected2893 GDD’s for 0°C base temperature. Same pa- rameter was calculated as 2719 and 2639 forTekirdağ and Edirne, successively. It has been cal- culated that the wheat needs 70 and more vernaliza- tion days to complete it’s average growth. Varia- tions in the Normalized Difference Vegetation Index(NDVI) on the agricultural and forest areas werealso estimated using the satellite data. Furthermore,correlations of the drought indices with the GDD’sand NDVI’s were investigated. Highest averageNDVI values were calculated for the flowering peri- ods of wheat (NDVI=0.45) and rice (NDVI=0.50),consequently. June showed the highest mean NDVI’sfor pine (NDVI=0.4), oak and beech (NDVI=0.65)when the forest areas were considered. Some grow- ing periods showed nearly linear correlations be- tween SPI and NDVI, while this was not the casewhen the whole growing periods were considered.On the other hand, high nonlinear relationships be- tween NDVI and BDG were estimated for both fieldcrops and trees.

Özet

Bitki-Toprak-Atmosfer arasındaki karmaşık süreç, bu süreci yöneten meteorolojik faktörlerin etkisialtında gerçekleşmektedir. Söz konusu etkinin olası sonuçlarının öngörülebilmesi, bitki gelişimi veverimi açısından da önemlidir. Bu sebepten, tarım ve orman meteorolojisi alanındaki araştırmalar,son yıllarda özellikle iklim değişikliği üzerine yoğunlaşmaktadır. Dünyadaki uygulamaların izlene- rek, karşılaşılan sorunların ve çözüm seçeneklerinin araştırılması, tarımın önem taşıdığı Türkiyeiçin de gereklidir. Trakya, yüksek tarım potansiyeli ve sanayi bölgelerine yakınlığı nedeniyle fenolo- ji ile kuraklık bakımından araştırılması gerekli bir bölgedir. Bu çalışmada, buğdayın olası iklim de- ğişiminden etkilenme durumu, Trakya Bölgesi’nde kışlık buğday tarımının yapıldığı illerden Kırkla- reli’nde açıklamalı bir bitki-iklim simulasyon modeli (CERES-Wheat) kullanılarak incelenmiştir.Model 1975-2005 arası ortalama gelişme dönemleri için buğday dane verimini %3.1’lik bağıl hataile tahmin etmiştir. Bunun ardından model girdi altyapısı, sırasıyla hassasiyet analizleri ve iklimdeğişimi senaryoları için düzenlenerek simulasyon sonuçları analiz edilmiştir. Yağışın %40 azal- ması durumunda verim %38.4 düşmektedir. Buğday, sıcaklık artışlarına da olumsuz verim tepkilerivermektedir. Karbondioksit ($CO _2$) konsantrasyonundaki artışların verimi artırıcı etkisi dikkat çek- mektedir. $CO _2x2$ uygulamasının verimi %10.5 artıracağı öngörülmüştür. Birden fazla meteorolojikparametrenin birlikte değiştiği simulasyonların verime etkisi de fazlalaşmaktadır. 2071-2100 arasıdönemin senaryo sonuçları, ortalama buğday veriminin Kırklareli’nde %9 oranında artış göstere- ceğine işaret etmiştir. Bu artış, ekstrem sıcak gelişme dönemi (2099-2100) için ortadan kalkmakta- dır. Ekstrem kurak gelişme döneminin (2085-2086) verim değeri ise 1975-2005 ortalamasının%65’ini karşılayabilmektedir. Buğday genelde $CO _2$ artışlarına en olumlu verim tepkilerini vermiş,tersi durum ise yağış azalışı için belirlenmiştir.