The role of spatial and temporal fluctuations of climatic parameters in dry land wheat yield (Case study: Kaleibar and Khodaafarin County)

Recognition of climate and doing research about climatic requirements of farm plants can be regarded as main factors in the production process. According to the importance of the climatic fluctuations in rainfed productions, in this study effect of spatial distribution and temporal variation of climatic elements on wheat yield was studied in dry land farms of Kaleibar and Khodaafarin counties. For this, distribution of precipitation parameters was mapped in GIS environment and year-to-year variety of temperature and rainfall analyzed by drawing of charts. And thus with using wheat growing requirements (including desired climatic conditions), ability to meet the climatic needs of this valuable plant were examined. In addition by running of stepwise multivariate regression model between 16 meteorological parameters and average wheat yield, the role of climatic fluctuations in dry land wheat yield identified and the best predictive model determined. Final results of this study show the fact that the importance of each of temperature and precipitation factors differ according to different phonologic stages of wheat at the study region. Although it seems that the mean annual rainfall in study area appears desirable but large fluctuation from year to year as well as small amount of rain in Khordad(June) are the main limitations of rain fed wheat cultivation. Temperature in germination and grain filling stages are created ideal condition but at the flowering stage temperatures are cooler than optimal physiological threshold. The stepwise regression presented a model with 7 meteorological parameters that can be explain a significant impact of climate parameters on dry land farming wheat yield at 95% confidence level on the study region.