INTENSIFICATION OF CALLOGENESIS IN GRAPEVINE GRAFTED CUTTINGS THROUGH THE APPLICATION OF BIOLOGICALLY ACTIVE PREPARATIONS

Abstract

A critical stage in the production of grafted grapevine planting material is the development of callus tissue at the graft union between the rootstock and the scion, as this process determines graft compatibility, survival rate, and overall quality of grafted cuttings. Callogenesis depends on the anatomical characteristics of shoots, polarity, apical dominance, and the formation of an insulating layer. To intensify this process, biologically active preparations (BAP) are applied to stimulate cell division, enhance cambial activity, and promote uniform callus development. The objective of the study was to determine the effect of modern biologically active preparations and different grapevine rootstocks on the intensification of callogenesis in grafted cuttings. The research was conducted at the National Scientific Center “V. Ye. Tairov Institute of Viticulture and Winemaking” of the National Academy of Agrarian Sciences of Ukraine in 2023–2025. The experimental material consisted of grafted cuttings of the cultivars «Original» and «Zahrei», produced on the rootstocks «RxR 4923», «Berlandieri × Riparia Kober 5BB 9191», and «Berlandieri × Riparia SO4 9701». The graft union was treated with gel-based preparations Clon M and Clonex Gel and stratified in a coconut substrate for 21 days. For each experimental variant, 150 grafted cuttings were prepared. The number of grafted cuttings with circular callus, rejected grafted cuttings, fresh and dry callus weight, tissue hydration, and dry matter content of the callus tissue were determined. The results showed that the application of BAP increased the formation of circular callus at the graft union of the cultivar ‘Original’ by 2.4–10.3% (Clon M) and by 2.4–5.7% (Clonex Gel) compared to the control. In the cultivar «Zahrei», the increase ranged from 4.0–16.0%, depending on the rootstock and preparation used. The percentage of rejected grafted cuttings decreased to 16.0%. The most effective rootstock was «Berlandieri × Riparia Kober 5BB 919», which enhanced callogenesis in grafted cuttings of «Original» by 10.4–17.2% and of «Zahrei» by 0.5–13.4% compared to the control. Comparative analysis of the cultivars demonstrated that «Zahrei» exhibited superior callogenic capacity. Assessment of qualitative indicators of callus tissue confirmed an increase in tissue density and dry matter content following BAP application. In treatments with Clon M and Clonex Gel, tissue hydration decreased to 79.0–80.55% compared to 89.68–90.32% in the control, while dry matter content increased to 18.12–20.88%. Statistical analysis confirmed the significance of the studied factors: BAPs were the primary factor influencing fresh callus weight (contribution 88.01%), whereas dry callus weight was determined by multiple factors (BAP contribution – 54.99%, rootstock – 11.23%, grapevine cultivar – 6.75%, three-factor interaction – 12.86%).