PECULIARITIES OF SUMMER BUD GRAFTING OF CITRUS CROPS IN THE RUSSIAN HUMID SUBTROPICS

The paper presents the results on the obtained planting material based on the results of the summer bud grafting within citrus cultivars and hybrids. Observations and records were carried out according to the “Program and methodology of fruit, berry and nut cultivar studies”. The terminology is used in accordance with GOST R 70191-2022. The assessment of the eyes survival rate was carried out in the spring of the following year (March). The living eyes were green in colour, while the eyes that had not taken root were turning brown by this time. In general, there is a good compatibility of propagated cultivars and hybrids with the rootstock – Citrus trifoliata. The highest survival rate among mandarin was observed in the hybrid G-9952 (96.9 %), cultivars ‘Kowano Wase’ (95.0 %), ‘Kodorsky’ (94.4 %), ‘Miagawa Wase’ (92.3 %), ‘Solnechny’ (90.8 %), the lowest was in cultivars ‘Sochinsky-23’ (46.0 %), ‘Pioner-80’ (46.2 %), ‘Millennium-1’ (50.6 %) and ‘Unshiu’ (54.3 %). Among grapefruit, the highest survival rate was noted in the ‘Gulripshsky’ cultivar (82.1 %), the lowest was in the ‘Jubileiny’ cutivar (39.3 %), for the cultivar ‘Seedless’ it amounted to 60.0 %. For the ‘Washington Navel’ orange, the survival rate was 93.6 %, for ‘Meyer’ lemon cultivar (C. × meyeri) – 70.5 %. It was noticed that the survival rate of the eyes is largely influenced by the weather conditions of the year. The Pearson correlation results showed that there is a significant negative relationship between survival/temperature (-0.7971–0.9974) and a significant positive relationship between survival and humidity (0.7968–0.9779). In general, if bud grafting terms are observed, the grafting of the scion with the rootstock lasts for 30–50 days.