No abstract

Although historically a surplus food producer, Bulgarian agriculture has faced a downturn in recent decades. Local legume cultivars have lost favour with farmers and the canning industry, due to their low productivity in comparison with imported ones. Diseases and abiotic stresses are the most important factors limiting the production of edible legumes, costing farmers hundreds of euros in lost revenue each year. The overall objective of our ongoing bean mutation breeding programme was to enrich the gene pool of Phaseolus vulgaris L. and to develop genotypes resistant to Xanthomonas axonopodis pv. phaseoli (Smith) (Xap) and Pseudomonas savastanoi pv. phaseolicola (Burkh.) (Psp) using EMS. An elite line and common cultivar (an heirloom and a snap bean type) in Bulgaria, were selected as parents and the chemical mutagen EMS was used for generating mutations. In total, 1000 seeds were treated and the two generated M1 populations were grown in the field. All M2 mutant plants (1650 from initial line IP564 and 2420 from initial cultivar 'Mastilen 11b') were grown in field conditions and a number of phenotypic changes were observed on these mutated plants. They were also screened for Xap disease resistance via leaf artificial inoculation under greenhouse conditions. Individual plant selection was performed for the putatively resistant M2 plants. In the M3 generation these lines were screened using artificial inoculation with Xap and Psp pathogens (leaves and pods) under field conditions. Selected M3-M4 lines with confirmed disease resistance were tested for fresh pod quality. Yield tests were started in M4 and M5 generations and, according to their productivity performance, mutants were advanced to the M6/M7 generation for validation. The expression patterns of genes putatively involved in the resistance reactions towards two races of Psp were determined using qRT-PCR for the specific and reference genes. In conclusion, 50 plants with visible morphological changes and/or increased tolerance to the two targeted bacterial diseases were selected. A total of 20 advanced mutant bean lines are currently being evaluated for their competitiveness in multiple sites.

A laboratory equipment for combinations of convective and microwave drying is presented. It was applied for drying of parsnips. Lower energy consumption at microwave heating of the product at intermitted drying is confirmed in comparison to continuous convective drying with hot air. In addition, the influence of the drying process on the phenols and flavonoids contents in at continuous convective drying were investigated. The results give useful information for the organisation and the operating of the drying modes of vegetables.

The equilibrium moisture content of Pumpkin Seeds is studied and the sorption and desorption curves at temperature 20°C are obtained. The strain measurement method for taking down of sorption curves is used for the aim. Analytic dependences describing the sorption and desorption curves are derived. Values of equilibrium moisture contents for temperatures higher than 20°C (40°C, 60°C, 80°C) are obtained by using the method of Pass-Slepchenko. The results are presented in graphical and table form.

The granulometric composition of Pumpkin seeds of the “Samson” variety used as feedstock for food and vegetable oils producing industry are studied. Their geometric dimensions and physical indices are obtained experimentally. Results and dependencies necessary for designing and dimensioning of drying ovens from installation for vegetable oils production are obtained.