The productivity of potato varieties planted in spring depending on plant growth regulators under irrigation conditions in Southern Ukraine

Abstract

Purpose of the study was to determine the productivity of potato varieties planted in the spring depending on the plant growth regulators used. Methods. Field experiments were conducted during 2020-2021 on irrigated fields of the "Veles" farm in the Vasylivka district of the Zaporizhzhia region. The experiment included two factors. Experimental design: Factor A – variety: 1) Arizona; 2) Volumia; 3) Colomba; Factor B – plant growth regulator: 1) Without regulator; 2) Mover-N; 3) Kelpak RK. The experiments were carried out using generally accepted methods. Agronomic practices were used in accordance with the recommendations for growing potatoes on irrigated lands in southern Ukraine. The soil of the experimental plots was southern chernozem with low content of mobile nitrogen and medium content of mobile phosphorus and exchangeable potassium in the arable layer. The predecessor crop was winter wheat. Second generation seed potatoes grown on the farm were used as planting material. The planting density was 55,000 tubers per hectare. The planting tubers had an average weight of approximately 40 g. Potato plants were sprayed with plant growth regulators at the budding stage according to the experimental scheme. The application rate of the Mover-N growth regulator was 0.4 l/ha, and Kelpak RK was 3 l/ha. Soil moisture was maintained at 70-80-70% of field capacity during the following stages: emergence-budding, budding-flowering, and flowering-dying back of the foliage, respectively. Harvesting of the tubers began with digging up the potatoes followed by manual collection plot by plot. Meteorological conditions during the years of the study sufficiently reflected the climatic characteristics of southern Ukraine, allowing for reliable experimental data, conclusions, and recommendations for production under these soil and climatic conditions. Results. The highest number of tubers per bush was observed in the Arizona and Colomba varieties with the application of the Mover-N plant growth regulator, averaging 7.8 and 7.7 tubers per bush, respectively, for 2020-2021. The highest average yield of potato tubers over the two years was obtained from the Arizona and Colomba varieties, amounting to 33.8-34.9 and 33.3-34.3 t/ha, respectively, with the use of plant growth regulators, which was 3.0-5.5 t/ha more than the Volumia variety. The use of Kelpak RK growth regulator increased the potato yield by 2.7 % in Arizona, 2.1 % in Volumia, and 2.5 % in Colomba, while Mover-N increased the yield by 6.1 %, 5.2 %, and 5.5 %, respectively. The potato yield in all experimental variants was higher in 2020 compared to 2021 by 16.0-19.4 %. The highest marketable quality of potato tubers on average for 2020-2021 was in the Arizona and Colomba varieties, ranging from 93.7-93.9 % without the growth regulator to 95.8-96.2 % with the Mover-N growth regulator. The highest starch content in potato tubers was in the Arizona and Colomba varieties with the use of plant growth regulators, at 16.4-16.6 % and 15.2-15.3 %, respectively. The use of plant growth regulators increased the starch content in tubers by 1.9-3.1 percentage points in the potato varieties. The most effective was the action of Mover-N. The application of this growth regulator also contributed to an increase in the conditional yield of starch per hectare of potato crops. This indicator increased by 3.8-9.4 % in the varieties compared to the untreated variant. The highest conditional starch yield per hectare was in the Arizona and Colomba varieties. The lowest cost of 1 quintal of tubers was 349-356 UAH for the Arizona and Colomba varieties with the use of the Mover-N growth regulator. Net profit was highest, at 169,594-174,553 UAH/ha, also in the Arizona and Colomba varieties with the application of the Mover-N growth regulator. In these variants, the highest profitability level was also achieved, at 139.1-143.0 %. Conclusions. Under the irrigation conditions of southern Ukraine, for spring planting to achieve a potato yield of 34.3-34.9 t/ha with high quality and marketable product indicators, ensuring the highest net profit and profitability, it is recommended to grow the Arizona and Colomba varieties and treat the crops at the budding stage with the Mover-N growth regulator at a rate of 0.4 l/ha.