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In recent years, organic farming, or the production of organic food of plant or animal origin, has been increasingly discussed in our country. A few growers decided to reorient production on their farms. The aim of the study was to evaluate the yields of potatoes and tomatoes under organic, mineral and organic-mineral fertilisation within the framework of a multi-year vegetable crop rotation.The experiments were carried out on alluvial-meadow soil (Mollicfluvisol) in the village Tsalapitsa (42.191734 N, 24.580252 E), Plovdiv region, like every subsequent year, regardless of the crop experienced, the variants were placed on the same area. The results for the yields and the quality of production showed that there was a lack of a clear, unequivocal answer for the choice and recommendation of organic or mineral fertilisation. The highest yield of potatoes was obtained (3242 kg/da) in the variant with mixed fertilisation. The highest tomato yield was recorded in the variant with mixed fertilisation (4307.4 kg/da), and the lowest in the control (without fertilisation) – 1670.1 kg/da.The fertilisation system as a complex, dynamic mechanism is influenced by several factors. The integrated fertilisation system, i.e., the combination of mineral and organic fertilisation increases the overall efficiency, reflected in the productivity and some of the quality indicators of experimental crops, regardless of the increase in the degree of damage by insect herbivores and fungal pathogens.

Background: Lettuce (Lactuca sativa L.) is an annual plant with very rapid growth and a major species in the assortment of leafy vegetables. Plant parasitic nematodes are economically important pests of leafy vegetables in monoculture and intensive organic fertilization. The simultaneous cultivation of several plant species in the same area can overcome the disadvantages of crops from homogeneous crops. The purpose of this work is to determine the quantitative changes in soil nematode communities in the joint cultivation of medicinal and vegetable species. Methods: The experiments were carried out in a vegetation house. To create mixed crops, the plants the lettuce (Lactuca sativa L.), cutivar ‘Bohemia’, tagetes (Tagetes sp. L.), basil (Ocimum basilicum L.), calendula (Calendula officinalis L.) summer savory (Satureja hortensis L.) and arugula (Eruca sativa L. Cav.) were used. Result: The results of the nematological analysis showed a decrease in the number of nematodes when mixed growing of lettuce with arugula, calendula and tagetes. The mixed growing of lettuce and calendula resulted in a significant reduction in nematodes, with a Pf/Pi value of 0.3. As a result of the decrease in the nematode population, there was an increase in lettuce yields when mixed grown with arugula and calendula, compared to when grown alone. The study of plant parasitic nematodes based on comparative evaluation of different combinations of plants shows that combinations of crops can be applied as a control method in integrated plant protection systems.

The effects of Cd, Pb, and Zn uptake on plant morphology, photosynthetic parameters, antioxidant potential, and essential oil yield and quality in Ocimum basilicum L. and Origanum vulgare L. plants were evaluated. The plants were grown as a pot experiment in soil heavily polluted with Cd and Pb and on unpolluted soil. Both plants accumulated Cd, mainly in the roots, while Pb occurred in the oregano shoots only. The leaf blade thickness of both plants increased when grown in polluted soil. Basil plants responded to the action of heavy metals with increases in gas exchange, stomatal conductivity, and transpiration, but water-use efficiency declined. Gas exchange and transpiration were reduced in treated oregano plants, but stomatal conductivity and water-use efficiency increased significantly. In basil, the increased levels of low molecular weight antioxidants such as phenols and flavonoids were observed, while in oregano, ascorbate, glutathione, and phenols were enhanced. Enzymatic antioxidant defense was observed in both plants when grown in contaminated soil, mainly with glutathione peroxidase, quaiacol peroxidase, glutathione S-transferase, and glutathione reductase. Accumulated levels of Cd, Pb, and Zn in plant organs resulted in a reduction in essential oil yield in basil only.

Garden bean plants (Phaseolus vulgaris (L.) Savi.) cv. Xera were grown under glasshouse conditions at optimal fertilizer rates using mineral, organic, and foliar fertilizers previously established in a model pot experiment. It was shown the favorable effect of the foliar feeding on the biomass accumulation in the different vegetative organs and formation of fresh products with low levels of nitrates and nitrites. In the leaves of the plants with foliar feeding higher levels of nitrate reductase enzyme activity are observed which contributes to more intensive nitrogen uptake. No differences are established among the variants with different fertilizer sources regarding plastid pigment content.