Potato yield dependence on weather conditions

The purpose of the study is to assess the influence of temperatures and precipitation in different phases of potato development on its yield and product quality. In the course of ten-year observations (1995-2005) at the variety testing station of the Tomsk Region, the following were determined: the duration of each five phenophases of eight varieties; calculated the amount of precipitation and heat resources (the sum of all temperatures above 5 °C) for each of them. Analysis of variance revealed a clear localization of only two groups of varieties in terms of early maturity (early and mid-maturing). Correlation analysis showed a positive average in terms of strength between the yield and the amount of precipitation in phase II, negative - with the sum of temperatures in phase IV, an average negative - between the proportion of large tubers in the structure of the crop and the amount of precipitation in phase IV. A reliable dependence of the yield of potatoes on the amount of precipitation in phase II, the amount of temperatures in phase IV and lesions by late blight has been derived. The lowest productivity of late varieties, forming smaller tubers, is shown. The yield of early varieties is on average 127.3 kg/ha; mid-early - 156.0; medium - 99 c/ha. The share of large tubers in the structure of the yield is 3.5 % for medium early and medium varieties; the share of small tubers is 82.3 % for early varieties, 93.5 % amounts for medium early varieties and 96.7 % amounts for medium ones. The results obtained provide a quantitative assessment of the patterns previously described in the scientific literature. Lack of precipitation at the beginning of flowering leads to maximum yield losses, and this relationship is much weaker in other phases of the growing season, when dehydration is compensated by endogenous moisture reserves in parent or daughter tubers. The negative effect of elevated temperature during flowering on productivity causes the transformation of stolons into aerial shoots, overgrowth of tubers and a sharp decrease in their size. A clear localization of only two varietal groups according to early maturity (early and mid-maturing) was revealed instead of four traditional ones, which makes it possible to optimize agrotechnical measures for their cultivation.