LONG-TERM ANALYSIS ON CLIMATE-DROUGHT-YIELD RELATIONSHIP; ESKISEHIR CASE STUDY
In this study, the structure of climate characteristics (precipitation, minimum, maximum and average temperature, relative humidity), their changes by years, and analysis for drought and stress analysis by SPI (Standard Precipitation Index), and for temperature stress by THI in Eskişehir province were analysed. In addition, the relationship between climate factors and yield was determined by factor analysis. Results showed that although precipitation appears slightly arid in the 50-year period, no excessive change or decrease was observed on precipitation in Eskişehir. In addition, about 2°C increase was recorded at minimum, maximum and mean temperatures. PCA analysis revealed that, the precipitations in March, April, May, June, October, March-June period and total precipitation are closely related to grain yield in wheat. When the mean, minimum and maximum temperatures are taken into consideration, the temperatures in May and June, October and March-June period and June-August period are also very effective in the development of the plant. Since, relative humidity is closely related to precipitation, relative humidity in June, July, October, March-June period and August-November period affects the yield together with precipitation. While there is not a big change in precipitation, almost 2ºC increase in temperatures is determined and this increase is the trigger of drought. There is an increase in evapotranspration more and more, that expresses water loss from soil and plants due to the gradual increase of temperature on a 50-year basis, it is highly probable that, the plant needs to use more water for transpration due to the increasing temperature. This shows that due to the increasing temperature, water loss increases and accordingly, there are gradual increases in drought.