Effects of moisture conditions on winter wheat yield using the Palmer drought severity index: A case study of the Rostov region, Russia

The paper examines the effect of fluctuations in moisture conditions in different seasons on spatiotemporal changes in winter wheat yields in the Rostov region of Russia in 2010-2024. The Palmer drought severity index (PDSI) was used as a moisture indicator. In general, the yield value from the maximum values of 4.0–5.0 t/ha in the southern and western parts of the region decreases with removal to the northern and eastern parts to the minimum values of 2.0–3.0 t/ha. During the study period, most of the districts were characterized by a significant trend of increasing crop yields at an average rate of 0.14 t/ha per year. There were no spatial features in increasing yields. During this time interval, periods of increasing and stagnating crop yields were observed in the region, and these dynamics correlated with fluctuations in the PDSI index. The most significant influence on the yield of winter wheat in various regions of the region was exerted by the moisture conditions in the spring season. As a factor, this indicator explained, depending on the region, from 24.8% to 69.2% of the interannual variability in the yield of this crop. The influence of moisture conditions in the autumn and winter seasons was less pronounced. The most significant decrease in yields was observed in 2013, when moderate and severe droughts were observed in most of the region during the previous autumn, winter and spring seasons. Our experience has shown that PDSI is a fairly informative and reliable indicator that can be successfully used in analyzing the impact of moisture conditions on winter wheat yields.