Modeling of the Saffron Yield Based on Meteorological Extreme Events (Case study: Birjand)

Weather, whether in terms of averages or events, is an important determinant of yields. Extreme weather events, already a significant challenge for crop producers, are predicted to increase under future. Extreme weather events are expected to increase worldwide, therefore, anticipating and calculating their effects on crop yields is important for topics ranging from food security to the economic viability of products. During recent years, monitoring of saffron has revealed that in spite of increase in Iranian cultivated areas in Iran. Its yield per unit area has decreased. Due to its importance and determinant that it is highly dependent on meteorological events, recognition and evaluation of extreme events and their influences on saffron yield can lead to a better utilization and management planning. To evaluate the extreme climate indices trend (during 1991-2015), 38 indices of rainfall and temperature that defined by the CCl/CLIVAR/JCOMM team were used. Afterward, using the stepwise regression analysis, the effects of weather extreme events were evaluated. Then, by selecting the best indices, saffron yield model was proposed. Analysis of indices demonstrate the trends of region warming and precipitation decrement. From the results of this study, it could be concluded that the incremental trend of warming extreme indices coupled with the negative trend of precipitation are the most significant factors in decrease of saffron yield.