Relationship Between Weather Conditions and Climate Indices with Rainfed Crop Yield

Crop yield in rainfed conditions is greatly influenced by meteorological parameters such as rainfall and evapotranspiration. As climate indices (AO, NAO, PNA, NINO-3.4, and AAO) are available for the future months, finding the relationship between crop yield with meteorological parameters and the relationship between meteorological parameters with climate indices can be very useful in predicting annual fluctuations in rainfed crop yield. In the current study, the association between rainfall, PET, and AI with barley and wheat rainfed detrended yields (1990-2016) and the relationship between AI and climate indices (AO, NAO, PNA, NINO-3.4, and AAO) were assessed for Chaharmahal and Bakhtiari province in the west of Iran. All associations were assessed at annual and seasonal (wet and dry seasons) scale considering both concurrent and lag correlations (1-year and 2-year lag). Our results showed a significant correlation between rainfall and AI with crop yields in all study locations except Kouhrang in both annual and wet season time scales. The results indicated that except Kouhrang, where the temperature is a limiting factor to crop yields, in all Chaharmahal and Bakhtiari areas, drought is one of the key factors of annual yield variability (significant correlation between AI and crop yields). The significant correlation between AI with NINO-3.4 and AAO also was observed in both annual and wet season time scales. It seems that NINO-3.4 and AAO indices can be useful to estimate grain yield of rainfed barley and wheat, predict drought occurrence, and take possible actions to counter such conditions.