Object of study – technological process of seed potatoes reproduction in irrigation conditions оn the south of Ukraine. Aim – determination of seed productivity of potato varieties depending on their biological potential and nutritional conditions during reproduction of basic seed potato under irrigation conditions оn the south of Ukraine. Methods – field: visual, measuring; laboratory: chemical; statistical; calculation and comparison. Results – The application of mineral fertilizers in the dose of N45P45K45 and N90P90K90 significantly improved the yield structure of biological maturity superelite potato: increased the number of tubers under the bush on 21 and 26 %, the weight of the average tuber – on 12 and 16 %, seed tuber 19 and 25 %; yield of seed fraction – on 7 and 8 %; yield of conditioned seed potatoes increased on 56 and 72 %, reproduction rate (quantity) on 21 and 28 %, (weight) – on 37 and 48 %, according to the level of fertilizer. The use of growth regulators Emistim C, Regoplant and Stimpo with mineral fertilizers at the dose of N45P45K45 also improved the yield structure of basic seed potatoes of biological maturity: the number of tubers under the bush increased by 6, 9 and 6 %, the average tuber weight - by 3, 5 and 3 %, seed - by 6, 11 and 7 %, the yield of seed fraction - by 3, 5 and 3 %. The Regoplant use increased the yield of conditioned seed potatoes on 25 %. Reproduction rates by number and weight increased from the use of regulators by 2, 9, 5 and 6, 15 and 10 %. The maximum productivity of biological ripeness superelite (SE) of early and middle-early varieties Skarbnytsia and Levada was formed with mineral fertilizers at a dose of N45P45K45 in combination with Regoplant complex treatment (21,85 and 22,12 t/ha, respectively), and with N90P90K90 without growth regulators treatment. The cultivation of the medium-ripe variety Yavir requires an increased fertilizers dose of N90P90K90 – the yield was 22,65 t/ha. The maximum level of conditional net profit, profitability at the lowest unit cost is formed growing seed potato of early-maturing variety Skarbnytsia and middle-early – Levada with Regoplant treatment on the background of N45P45K45 mineral nutrition: 90,97 k UAH, 147 %, 2,84 k UAH/t; 92,71 k UAH/ha, 150 % and 2,81 k UAH/t, respectively. The optimal indicators of economic efficiency were obtained using mineral fertilizers N90P90K90 with growth regulator Emistim C at reproducing medium-ripe variety Yavir – 92,9 thsnd UAH/ha, 142 % and 2,92 thsnd UAH/t, as well as without regulators use – 91,82 k UAH/ha, 140 % and 2,90 k UAH/t, respectively. Novelty – for the first time on irrigation for Ukraine south conditions features of growth, development, formation of morpho-physiological, economically valuable signs, seed productivity of different maturity groups potato varieties in spring planting depending on complex action of mineral fertilizers and growth stimulators was established; the influence of the studied factors on the photosynthetic potential of potato plants, microbiological activity and agrochemical parameters of the soil was established. The scientific value – the optimal method of complex application of mineral fertilizers and growth regulators was determined, which is guaranteed to provide high yields, yield of conditioned seeds, high reproduction rate of potato varieties adapted to the conditions of the south of Ukraine while saving material and labor resources. Sector – agriculture.
