The Effects of NPK Fertilization on Growth Dynamics of Potato Plants Under Non-Irrigated Conditions

The effects of NPK fertilization on growth dynamics of potato plants under non-irrigated conditions were studied during 2013-2014, in Brasov experimental conditions. In this experiment were used two potato varieties, Christian and Roclas. Two different nitrogen fertilizers levels, N100 kg/ha and N200 kg/ha were used. The variants were done with two complex fertilizers given before planting: C15-15-15, for NPK report of 1:1:1 and C5:10:22, supplemented with ammonium nitrate through which was realized NPK 1:0.9:2 report. Dynamics of biomass components, yield accumulation and tubers starch content was monitored by performing six harvests on dynamics. Maximum aerial mass was recorded in the first two observations in both varieties, after 25 and 37 vegetation days in 2013 and 22 and 34 vegetation days in 2014. In 2013 maximum production was obtained in fertilized variant with N200:P180:K400, to Christian variety 975 g/plant (at 52 days after emergence DAE) and to Roclas varieties 1021g/plant (at 80 DAE). In the two years studied, the maximum levels of starch content were registered in variants N100, P100: K100, starting with 61-62 DAE, after that, on this variant the increases of starch content have become insignificant. As a result of various hydrothermal conditions in those two years, the maximum starch content of 16.316.7% recorded in 2013 to Christian, were reduced in 2014 to 14.5-15.1%. The effects of climate on tuber starch content could not be manifested to Roclas variety, maximum content exceeded 17% on both years. Doubling doses of NPK from both reports resulted in declines of tuber starch content which was manifested stronger in the year 2014 with higher humidity.