International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

In order to determine the influence of different rates of irrigation and fertilization on the growth, yield, and some yield-related characteristics of three genotypes of tomatoes, research was carried out at IVCM – Plovdiv in an unheated steel-glass greenhouse of the “Venlo” type. The experiment was carried out with three modes of irrigation: optimal – 100%, reduced – 75%, and increased – 125%, using water-saving irrigation technologies and three modes of fertilization – optimal – 100%, reduced – 75%, and increased fertilization – 150%. The amount of watering and irrigation norms, the number of waterings for the growing season of greenhouse tomatoes were determined based on soil type, and climatic conditions in the region of Plovdiv. An optimal or high irrigation rate combined with reduced or optimal fertilization leads to maximum yields in all three tomato varieties. A specific reaction of the variety was observed – in “Hayet” and “Pink rock ”varieties, maximum yields (14.1 t/ha and 8.8 t/ha) were obtained in the variants with 100%/75%, while in the “Malduo” variety, the highest yield was obtained (8.6 t/ha) in the variant with 125%/100%, irrigation/fertilizer rate. In the three studied varieties of tomatoes, the lowest yield was reported when the irrigation rate was reduced by 25%, which shows that the reduction of the irrigation rate by 25% is within the limits of the critical, while the reduction of the fertilizer rate by 25% is permissible.

An analysis has been made of the research work to determine the impact of water deficit on the quantity and quality of sunflower production. Studies have also taken into account the more frequent drought in the last decade – soil and atmospheric. Research shows that its good drought resilience allows it to be grown under irrigation conditions, but is sensitive to severe droughts, especially in the critical stages of development which leads to poor quality and drastic decrease in yield, and in some years to the lack of yields. The results show that sunflower irrigation has a large reserve for obtaining additional yield, which has been established through experiments in different parts of the country. The increase in irrigation is about 30-40%, and critical for water stress is the period of 20 days before and 20 days after flowering.

An analysis has been made of the research work to determine the impact of water deficit on the quantity and quality of sunflower production. Studies have also taken into account the more frequent drought in the last decade – soil and atmospheric. Research shows that its good drought resilience allows it to be grown under irrigation conditions, but is sensitive to severe droughts, especially in the critical stages of development which leads to poor quality and drastic decrease in yield, and in some years to the lack of yields. The results show that sunflower irrigation has a large reserve for obtaining additional yield, which has been established through experiments in different parts of the country. The increase in irrigation is about 30-40%, and critical for water stress is the period of 20 days before and 20 days after flowering.