Biologization of apple cultivation technology: effect of a humic biostimulant on yield and fruit quality

Abstract

The aim of the research (2024–2025) was to assess the effect of the humic biostimulant GUMI-90M (BashInkom) on the formation of yield and fruit quality of the apple variety Prikubanskoe on the SK2 rootstock under the conditions of Krasnodar Territory. The preparation was applied as foliar treatments before flowering at rates of 45, 60 and 75 g/ha; part of the yield was subjected to postharvest treatment with 1-methylcyclopropene (1-MCP). The trial was established in the orchard of the OPH «Tsentralnoe» in four replications. Fruit set and fruit drop, yield, commercial grading and the contents of ascorbic acid, P-active catechins, potassium, magnesium and calcium were determined; the data were processed by one-way analysis of variance. The treatments increased fruit set by 5.0–6.5 % relative to the control; at a rate of 75 g/ha fruit drop decreased by 16.6 %, the proportion of fruits retained until harvest reached 41.0 % against 24.4 % in the control, and yield increased by 2.4 t/ha (12.4 %) – at the level of a tendency, within LSD05. The contents of vitamins C and P, potassium, magnesium and calcium in the fruits increased by 2.8-11 %. Fruit ripening was more extended, which widens the optimal harvest window. The combination of foliar treatments with postharvest 1-MCP provided, after five months of storage, an output of extra and first commercial grade fruits of 92–94 % against 78 % in the control (+14–16 %). The preparation at an application rate of 75 g/ha is advisable for inclusion in zonal agrobiotechnological systems of apple cultivation in order to increase orchard productivity and improve fruit quality during long-term storage. Keywords: apple, Prikubanskoe variety, humic biostimulants, GUMI-90M, 1-methylcyclopropene, fruit set, yield, fruit quality, mineral composition, storage.