Study of some physiological parameters in the plum cultivars ‘Jojo’ and ‘Topgigant Plus’ (Prunus domestica L.), grafted on the clonal rootstock ‘Docera 6’ 
(P. domestica × P. cerasifera)

The seed generations of the species Prunus cerasifera Ehrh., are used as a standard rootstock for plums in Bulgaria.
The new clonal rootstock ‘Docera 6’ (P. domestica × P. cerasifera) attracts the attention of breeders and fruit growers in countries like Bulgaria, where Plum pox virus (PPV) is endemic.
The current study was conducted in an experimental orchard at the Fruit Growing Institute – Plovdiv, Bulgaria planted in 2016. The study aimed to investigate some physiological parameters of the plum cultivars ‘Jojo’ and ‘Topgigant Plus’ (P. domestica) grafted on ‘Docera 6’. The same cultivars grafted on the standard seedling rootstock Prunus cerasifera Ehrh. were used as control.
In 2021, during two phenological stages, “fruits about half final size” (BBCH 75) and “fruit ripe for picking” (BBCH 87), the following indicators were determined: annual shoot length and thickness, number of leaves, fresh, dry mass and leaf area, content of photosynthetic pigments and total soluble proteins, as well as chlorophyll fluorescence (JIP test). For both studied cultivars, the length and diameter of the annual shoots were smaller in comparison with those grafted on ‘P. cerasifera’, although statistically, the difference was significant only for ‘Jojo’. During both phenophases there was no significant difference in the content of photosynthetic pigments in both cultivars grafted on the two rootstocks.
The results of the chlorophyll fluorescence analysis showed that the maximum quantum yield (Yield=Fv/Fm), reflecting the photochemical activity potential of Photosystem II, varied between 0.839 and 0.845 in all studied variants, which corresponds to healthy, unstressed leaves.
For the parameters of the chlorophyll fluorescence (JIP test) in the cultivar ‘Jojo’. differences between the two rootstocks and during the two phenophases were reported, while in the ‘Topgigant Plus’ cultivar they were observed only during fruit ripening.

XXXI International Horticultural Congress (IHC2022): International Symposium on Innovative Perennial Crops Management

N. Dimitrova, M. Nesheva, L. Nacheva, D. Aleksandrova

photosynthesis, chlorophyll fluorescence, JIP test, breeding

https://doi.org/10.17660/ActaHortic.2023.1366.19