A New Approach to the Identifying of the Extreme Climate Effect on the Wheat Yield Reduction in the South of European Russia

The change in seasonal extreme climatic conditions driving low wheat yields in the South of European Russia in the period of 1991-2019 compared to 1961-1990 has been investigated. The extreme temperature conditions are more important than the extreme precipitation regimes from the standpoint of assessing their total yearly impact on the wheat yield. A new proposed integral indicator takes into account the cumulative effect of seasonal extreme temperature and precipitation regimes most often accompanied by a shortage of wheat yield. Despite the positive changes in winter and spring, changes in extreme temperature and precipitation regimes in recent decades were unfavorable for wheat growing in the study area due to the negative statistically significant changes observed in summer and autumn.