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A study of local and introduced walnut cultivars was carried out at the Fruit-Growing Institute – Plovdiv in the period 2018 – 2020. Four introduced walnut cultivars – two Romanian (‘Valmit’ and ‘Valeris’) and two Turkish (‘Şebin’ and ‘Yalova 1’) – and the standard Bulgarian cultivars ‘Izvor 10’ and ‘Silistrenski’ were the object of the study. Their vegetative habits were investigated and biometric measurements of the nuts were performed. Based on the results obtained the pomological characteristics of the studied cultivars were evaluated. When grown in the conditions of South Bulgaria, the cultivars introduced from Romania – ‘Valmit’ and ‘Valeris’ and from Turkey – ‘Yalova 1’, are characterized by very large nuts. ‘Izvor 10’ and ‘Şebin’ have a high kernel ratio.

This paper describes research on the application of tissue culture techniques to the micropropagation of interspecific rootstock ʹDocera 6ʹ. The experimental work was carried out in the period 2017-2018, in the in vitro propagation laboratory of the Fruit Growing Institute Plovdiv. Аxillary buds were employed as initial explantеs in two different seasons (March-May; September-October). The action of the mineral medium was studied in the multiplication stage. The best result was obtained on LS medium included BAP 0.5 mg/l and IAA 0.05 mg/l. Тhe obtained average multiplication rate is 3.08. The concentration of auxin applied to the basal medium influence the quality of the root system Treatment with high concentrations of IBA added to the rooting medium gives the best results (V5). Тhe influence of the season on growth and development of micropropagated ʹDocera 6ʹ rootstock during ex vitro acclimatization is also part of our research. The spring acclimatization gives better results than the autumn.