An analysis of yield dynamics in Peredovik sunflower variety in the conditions of the North Caucasus Region

The results of observations for 1971–2002 were used to analyze the long-term trends of yield and the duration of the growing season in the sunflower variety Peredovik. The regression analysis has shown that the growing season duration decreases with the increase in the sum of temperatures above 15 °C. The yield of sunflower was negatively associated with the sums of temperatures and the sums of precipitation in May–August, and positively with the precipitation in April. According to the regression analysis in differences, the main factor influencing the yield variability was the hydrothermal coefficient for the period with temperatures above 20 °C, the second factor was spring precipitation. The possible presence of a non-linear trend in yield dynamics that is not related to weather and climate conditions has been revealed. With the sustained tendency of the last 30 years towards an increase in temperatures and a decrease in precipitation in April, the growing season will keep shortening and the yield decreasing.