Productivity of ethylene-treated seed potatoes (Solanum tuberosum L.) depending on growing conditions

In recent years, the production of potato (Solanum tuberosum L.) in Russia's private sector has been declining, giving way to industrial production which currently amounts to 8.2 million tons per year. This, in turn, increases the requirements for storage technology which should provide the possibility of simultaneous treatment of thousands of tons of seed potato for cultivation on a large scale, increasing the profitability. It is known that ethylene suppresses apical dominance at the beginning of tuber germination and thereby contributes to formation of a larger number of lateral sprouts from which additional stems are growing. However, the issue of ethylene-treated tubers response to growing conditions has not yet been studied. We have developed for the first time an original mathematical model to calculate the mineral fertilizer doses and irrigation rates that will ensure maximum realization of the biological potential of ethylene-treated seed potatoes. The aim of the research was to evaluate the physiological effect of the phytohormone ethylene on the biochemical parameters and productivity of potato plants obtained from seed tubers treated with ethylene, and to develop a mathematical model of the dependence of the commercial yield on mineral nutrition and moisture supply of plants in the second half of the growing season. The research was carried out at the experimental site Korenevo of the Russian Potato Research Centre (Moscow Province) in 2022-2023. Ethylene gassing was carried out in a 1000-ton potato storage facility using equipment of the Restrain Company Ltd. (Great Britain). Potato ( S. tuberosum ) was grown on sod-podzolic sandy loam soil. In the experiment, seed tuber exposure to ethylene was factor A which includes treatment I without gassing (control) and treatment II with gassing at a dose of 15 ml/m3 from November to the end of April). Factor B was medium-ripened potato cultivars Grand and Vympel. Factor C was fertilizer dose for local application during ridge cutting (I - N30P30K45, II - N60P60K90, III - N90P90K135, IV - N120P120K180. Factor C was precipitation from the second decade of July to the second decade of August inclusive (I - 57.5 mm, or 39.8 mm less than the average long-term norm, II - 135.2 mm, or 37.9 mm more than the average long-term norm which is 97.3 mm for the specified period). Potato was planted in the first decade of May with a density of 45 thousand tubers/ha and a 75 cm row spacing. Biochemical, biometric indicators and potato yield were assessed. The physiological effect of the phytohormone ethylene on the shortening of tubers dormancy of medium-ripened potato cultivars Grand and Vympel was revealed, accompanied by a decrease (р ≤ 0.05) in their starch content by 0.3 % and an increase in sucrose content by 0.06 %. Tuber weight loss during long-term storage increased by 0.4-0.6 % (р ≤ 0.05). There was a more active and uniform germination of the lateral buds with simultaneous suppression of the apical ones. The height of plants increased by 2.6-8.4 %, the number of stems per plant by 27.7-37.1 %, leaf surface area by 4.6-20.2 %, commercial yield by 7.8-26.5 % (р ≤ 0.05). The greatest increase in indicators occurred when the doses of mineral fertilizers increased from N30P30K45 to N60P60K90 with low moisture supply of plants, and from N60P60K90 to N90P90K135 with high moisture supply. Using analysis of variance it was found that the most significant factor for the commercial potato yield formation is the dose of mineral fertilizers (69.6 % effect), followed by the amount of precipitation in the second half of the growing season (8.6 %), treatment of tubers with ethylene (7.2 %) and the cultivar (4.8 %). Based on regression analysis, we have developed a mathematical model that predicts the commercial yield of potatoes with high accuracy (R2 values for ethylene-treated potatoes and seed tubers without treatment were 0.85 and 0.82, respectively). The model allows for the efficient management of crop commercial yields by applying appropriate irrigation rates.