S11 - Session P1 - Drought and adverse spring frost response of different grafting combinations of plum in the South Central region of Bulgaria

Authors: Nataliya Dimitrova *, Marieta Nesheva, Nesho Neshev

Plum ( Prunus domestica L.) is one of the main stone fruit species for Bulgaria. It is grown all around the country. The laboratory and field tests of the plum clonal rootstock 'Docera 6' ( P. domestica × P. cerasifera ), conducted at the Fruit Growing Institute - Plovdiv, define it as a promising rootstock in terms of its reaction to the Plum pox virus (PPV). The characteristics that the rootstock induces to the grafted cultivar are essential to the practice. For selecting suitable farming practices, they need to be thoroughly explored. This study aimed to evaluate the response to abiotic stress factors of the cultivars 'Topgigant Plus' and 'Jojo' grafted on 'Docera 6' and the same cultivars grafted on Prunus cerasifera Ehrh. The research was conducted in an experimental orchard at the Fruit Growing Institute. In 2021 freezing air temperatures in the spring and continuous drought period in the summer affected the plums. In these abiotic stress conditions flowering growth stage flow, percentage of frost injured flowers, water deficiency in the leaves, average yield per tree and fruit biometry were determined. The data showed that the frost injuries were dependable on the cultivar and less dependable on the rootstocks. The highest percentage of frost injuries was recorded for 'Jojo' cv. n 92% when grafted on 'Docera 6' and 87% when grafted on P. cerasifera . In the conditions of continuous drought, the water deficiency calculated for the cultivars grafted on the clonal rootstock was higher n 33.24 % for 'Jojo' and 22.49% for 'Topgigant Plus'.