The effect of different phytohormone concentrations on callusogenesis and organogenesis in two cucumber genotypes were studied. It was established that the rate of plant regeneration depends on genotype, explant type and culture medium. Hypocotyls were found to be more responsive than cotyledons in morphogenesis. In vitro planlet-regenerants have been obtained in hypocotyls explants on culture medium with 1.0 and 2.0 mgL-1 BA for cultivar Gergana and in 1.0 and 3.0 mgL-1K-line 15B. Induction of regeneration in cotyledons were established only in cultivar Gergana on culture medium supplemented with 3.0 mgL-1 BA and in combination of 0.5 mgL-1IAA.

During the period 2014-2015 the effects of cucumber grafting on yield and fruit sensory characteristics were studied under glasshouse conditions. Three long type parthenocarpic cucumber cultivars were grafted on five cucurbit rootstocks. The aim of the study was to compare the yield, elements of productivity and fruit sensory characteristics in order to establish the most appropriate scion/rootstock combinations. The highest yield was recorded in combination cv. 'Kiara F 1 ' grafted on Cucurbita maxima × C. moschata F 1 . Rootstocks of Lagenaria and C. maxima and control treatments showed great earliness of cucumber scions. C. maxima × C. moschata F 1 rootstock induced the highest fruit number per plant. The effect of rootstock on fruit quality showed a significant variation in the value of sensory traits appearance, aroma, taste and total sensory evaluation depending on the scion and rootstock combinations. C. maxima × C. moschata F1, Lagenaria and C. maxima rootstocks demonstrated good compatibility with the studied cucumber cultivars. The choice of combinations between scion cultivar and rootstock species should be determined after preliminary studies of both components.

Cucurbita spp. is one of the most important vegetable crops in the world. They are characterized by great polymorphism according plants and fruits traits. The fruits are consumed in different ways as boiled, baked, dried or processed in puree and juice. The aim of the study was to assess variation of fruit sensory, chemical and morphological characteristics of Cucurbita genotypes in order to find appropriate parental components for the future high quality breeding programme. During 2-year period nine winter squash (Cucurbita maxima Duch.) and three pumpkin (Cucurbita moschata Duch.) genotypes originating from different geographical regions were tested on their morphological characters, basic chemical components and sensory profile. Cluster analysis and Principle component analysis were applied in order to identify similarities of different genotypes. According to the fruit characteristics and plant habitus significant differences were recorded. Considerable variation in the content of dry matter, ascorbic acid, total sugars, total pigments, beta-carotene and sensory assessment of the boiled fruits was established. Accession Moskatna carotina had the best flavour and chemical composition. The studied Cucurbita genotypes are a good basis for performing a breeding program to improve the sensory quality of fruits and increase basic chemical components especially those with antioxidant effect.

Abstract. Powdery mildew, caused by Podosphaera xanthii and Golovinomyces cichoracearum, is an economically important disease in melon worldwide. Genetic resistance is one of the most suitable strategies to control powdery mildew. During the last few years several races of the pathogens have been reported. The need to develop resistant varieties is a challenge for each breeding program. Leaf disc assay was used in phytopathology and breeding programs as a rapid and reliable method for evaluation of disease resistance in a large number of plant materials. The purpose of this study was to establish species and races of powdery mildew in Plovdiv region, South Central Bulgaria; to develop a suitable system of pathogen isolation and cultivation; to determine the resistance levels in different melon genotypes available in Maritsa Vegetable Crops Research Institute (MVCRI) - Plovdiv collection by the leaf disc assay. Fifty-three melon genotypes, including lines, varieties, hybrids and ten differential lines were tested. The data showed that causal agent of powdery mildew was race 1 of P. xanthii in Plovdiv region. Our experimental results indicated that for the long-term storage of powdery mildew it is preferable to keep a whole plant under in vitro conditions. This allows the preservation of powdery mildew for two months before transferring on a new tissue. Thirty-four of the tested melon genotypes reacted as immune or resistant and nineteen as susceptible. Resistant melon genotypes are a suitable source in initiating a new breeding program aimed to increase resistance to powdery mildew.

Editors and Sections Genetics and Breeding King et al., 2010). resulting in severe loss of yield and quality. Rhizoctonia solani, Rootstocks of Cucurbita maxima×Cucurbita moschata have Fusarium spp., Pythium spp. and root-knot nematodes become the most used hybrids for several watermelon, melon and (Meloidogyne spp.) are the most serious soil-borne diseases in cucumber cultivars, because of their properties related to the cucumber rhizosphere (Sharma et al., 1995; Al-Debei et al., 2012 (Punithaveni et al., 2015). Their presence can siceraria) and hybrid squash (C. maxima×C. moschata) were widely alter uptake of water and nutrients, interfere with translocation of used as rootstocks in watermelon production due to their resistance photosynthates and increase incidence and severity of Fusarium to fusarium wilt (Cohen et al., 2007; Davis et al., 2008). oxysporum f. sp.radicis-cucumerinum diseases (Ismail et al., 2012).The aim of this study was to screening cucurbitaceous Damping-off, as the most seedling root and crown rot disease, is a rootstock genotypes to root-knot nematodes (Meloidogyne spp.), limiting factor in cucumber greenhouse cultivation. Some species of Fusarium spp. and Pythium spp. in order to be used as rootstocks or Pythium and Phytophthora are the most important soil-borne as initial material for breeding. pathogens that cause damping-off and root rot (Rostami et al., 2015). Fusarium and Pythium species also act as a complex causing cucumber wilt (Bithell et al., 2012).The current management of nematodes has been done by Material and methodsusing plant resistance, crop rotation, culture practices or nematicides. Nematicides control is expensive and hazard to ground The study was carried out in the Maritsa Vegetable Crops water, environment and animal and human health. No commercial Research Institute, Plovdiv, Bulgaria during the period 2014 -2015.* e-mail: vinelina@abv.bg 63The investigation was conducted in glasshouse conditions. weeks after emergence. Both pathogens are incorporated in the containers after transplanting. It was made mixed infestation. Plant materialSixty days after soil infestation with both pathogens, the plants It was used breeding material from collection of Maritsa were uprooted and washed with tap water to remove the adhering Vegetable Crops Institute from following cucurbit species: soil particles. The rate of infestation of roots from pathogens was Cucumis sativus -Kiara F (control) commercial cultivar long recorded on five-grade scale (0-4), where 0 -no attack; 1 -hit single 1 root; 2 -affected 25% of the roots; 3 -affected 26-50 % of roots, 4 -parthenocarpic type (Dutch type), gynoecious type of flowering; affected over 50% of the roots. Gergana,TG, TD -salad type, monpecious type of flowering;The results from the experiments were processed Cucurbita maxima -СМ-720, SB-2, SB-3, Turban;mathematically. Lagenaria siceraria -Local. Root-knot nematodes (Meloidogyne spp.) test Results and discussionSeeds were sown in 400 mL pots with mix (peat:perlite -1:1). Ten plants per ...