O. Georgieva¹, N. Valchev²

¹Maritsa Vegetable Crops Research Institute, 32 Brezovsko shosse, 4003 Plovdiv, Bulgaria
²Department of Plant Production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria

(Manuscript received 16 February 2018; accepted for publication 21 May 2018)

Abstract. In conditions of growing tomatoes in the open field the effect of bioorganic fertilizers and growth regulators have been studied based on humic acids Nagro and Stimix on the main growth indicators, yield and immune response of plant in tomatoes for medium early production of the variety Milyana. It has been found that seed treatment and seedlings with the bioorganic products Nagro and Stimix improve the biometric indicators of seedlings and plants during vegetation and accelerate the process of flowering of tomato phenophases. Fertilization with those bioorganic fertilizers at phase flowering increases the earliest and total yield. The application of the technological complex of activities including fertilization with mineral fertilizers Nı6P20K22, treatment of seeds with organic fertilizers Nagro and Stimix, and spraying of plants with conventional plant protection products leads to reduction of attack from Phytophthora infestans and Alternaria solani in tomatoes.