The biological and chemical protection system's influence on the soil mycological composition, potato plant biometric indicators, yield structural indicators, productivity, as well as the potato tuber quality has been studied. It was determined that after the biological protection system application, the genus Penicillium fungi number decreased by 4 times, the genus Aspergillus – more than 2 times, Trichoderma sp. content – 2.5 times. There was an increase in the stem number in the variant with

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... biological protection by more than 2 times, compared with the control, and by 25%, compared with the chemical protection variant. The plant height in the two variants was 6.4-7.3 % higher than the control values. The potato tuber total number per bush in the biological protection variant increased by 40 %, and the tuber mass increased by 12.4-61.7% in comparison with other variants. The yield increase was 157.3 c/ha (50.4%) and 128.0 c/ha (39%) for the biological and chemical systems, respectively. The nitrate amount was within the normal range in all variants. The vitamin C highest content was noted in the variant with the biological protection application (9.3 mg/100 g of raw substance). The starch amount varied from 20.8% to 21.3% in all variants.