No abstract

Decreasing the application of agrochemicals, especially pesticides, in fruit growing practices is one of the most important problems placed by the European Commission of Agriculture with the aim of preserving human health and protecting the environment. The problem is a matter of urgency in the apple crop, which occupies a leading position by the number of pesticide treatments. Solving the problem necessitates the establishment of cultivars resistant or tolerant to the major diseases and pests. The aim of the present study is to test the resistance of in vitro obtained apple regenerants 'Čadel' ® , to the most widely distributed phytopathogens in apple-scab (Venturia inaequalis), powdery mildew (Podosphaera leucotricha) and fire blight (Erwinia amylovora). Varying concentrations of monospore cultures of the respective fungal pathogens isolated from naturally infected leaves and most aggressive bacterial strain from Bulgaria are used in the investigation. The acclimatized in vitro somaclones, 8-10 cm in height or at the 4 th-5 th true leaf development stage, are inoculated with the respective phytopathogens following standard or improved methods. It is established that 3 out of the studied clones demonstrated a complex resistance to scab and powdery mildew diseases and low susceptibility/ tolerance to the dangerous bacterial disease fire blight.

The experiments were conducted in the field of Agricultural University in Plovdiv, Bulgaria. A standard method was applied for cultivation in 5 replicates. Biometric evaluation of common bean (Phaseolus vulgaris L.), 10 mutant lines and 10 varieties, grown under rainfed and irrigated conditions was conducted. Main traits, associated with productivity in common bean: plant height, mass of plants with pods, number of branches, height of the first pod, number of fruit branches, number of pods per plant, weight of pods with seeds, number of seeds per plant, weight of seeds and average length per 10 pods were characterised. Stronger degree of variation in studied traits was observed in genotypes grown under irrigated conditions. It was found that the studied Bulgarian varieties are promising in terms of germoplasm for their introduction in hybridisation breeding schemes as well as in application of mutagenesis and biotechnological practices. D 2 -0,0125 M EMS mutant line (6) has the best manifestation of the studied traits among other mutant lines and it may be included in breeding schemes for evaluation as a new cultivar. BAT 477 cultivar (20) differs significantly by its traits from other genotypes, irrespective of the cultivation mode.