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

This paper deals with the productivity of irrigation water and the effect of irrigation on raspberries in the Chelopechene experimental field. We examined different regimes, keeping from full satisfaction of daily water needs of crop to irrigation with reduced by 20 and 40% irrigation norms and variant without irrigation
Moisture optimization in the active soil layer contributes to a significant increase and stabilization of yields, which for the test conditions range from 835 to 1074 kg / dka, with additional yields ranging from 404 to 627, kg / dka or from 47 to 59% on average for the study period. Established productivity irrigation rate is highest in the variants irrigated with a 40% reduction in the optimum norm and varies in units from 13.0 kg. ha -1.mm-1 to 24.0 kg.ha – 1.mm-1, and it is low in the irrigation variants with 100% irrigation rate, with the highest values reaching in the dry year 2000.

A study was conducted to determine the irrigation regime and its impact on the yield of three genotypes of greenhouse tomatoes in 2022 at the experimental field of MVCRI – Plovdiv in an unheated steel-glass greenhouse of the Venlo type. The experiment was conducted in three irrigation regimes:
Optimal 100%M, reduced by 25% and increased by 25%, using water-saving technology.
The size of the irrigation norms, the number of irrigations for the growing season and their distribution by development phases for the soil and climatic conditions of the Plovdiv region were determined.
The obtained results for irrigation of greenhouse tomatoes show that 18 irrigations were implemented during the growing season in order to maintain soil moisture between 85-100% of the maximum field moisture capacity for the conditions of Plovdiv from the beginning of May to the end of July.
The size of the irrigation rates by regimes varies from 14.9 to 24.7 mm, and the irrigation rates – from 268 to 447 mm. The maximum irrigation rates during the period with the most significant water consumption can be applied after 3-4 days and satisfy the needs of the plants. The analyzed results of the yields obtained from the three tomato genotypes at different irrigation rates show that the highest total yield of greenhouse tomatoes is formed in the variant with 125% implementation of the irrigation rate, followed by the variant with 100% irrigation rate, and the lowest, in the variant with 25% reduction in the irrigation rate.
Obtaining a good effect from irrigation and the most productive use of irrigation water is possible only when applying an optimal irrigation regime, consistent with the requirements of the crops grown.
A number of studies have been conducted in our country on the limiting factor – water. Their main goal is to establish the best efficiency of applying different irrigation regimes for irrigation under optimal and insufficient water supply. (Kireva et al 2020)
The best results in terms of water use in this crop are obtained when the soil moisture is above 85% of the WHC and is applied to water-saving irrigation techniques. This method fully meets the requirements for sustainable agriculture and ecological fruit production, including ensuring high yields and quality of production, reducing unwanted side effects. (Bucks et al.,1982; Kireva ,2020.)
The results obtained by (Mukherjee, S., et al. 2023) show that physiological characteristics, yield and water productivity are significantly influenced by the irrigation system and soil moisture regime, with drip irrigation improving the average yield of tomatoes by 25%.
It was found that reducing the optimal rate (100% M) with a water stress of 50% (50%M), a significant decrease in yield (13.16%) was observed in greenhouse tomatoes (Wu et al. 2022 ; Lu et al. 2019 ). Alternatively, Wu et al. ( 2022 ) stated that under optimal irrigation conditions, tomato plants produced more fruits than those grown under deficit irrigation.
With the studies of the mutual influence of different irrigation regimes on the yield of tomatoes grown in a polyethylene unheated greenhouse, it was found that the impact of irrigation on yield has a greater effect at higher levels of irrigation rate, (Stoyanova A. et al.,2020; Stoyanova A. et al. 2019).
Studies of the irrigation regime and its influence on the yields of tomatoes grown in plastic greenhouses using drip irrigation are quite scarce, and the studies carried out in our country are for the conditions of the Sofia Field (Aboamera M. 1992; Kireva,; Kireva R.,2020) and for St. Zagora (Stoyanova An. et al. , 2020), which cannot be indicative of other agro-climatic regions of the country, which are characterized by different soil and meteorological conditions. Given the above, it is evident that research is needed to establish the complex influence of the irrigation regime on the quantity and quality of the yield of tomatoes grown in glass unheated greenhouses for the soil and climatic conditions of a region with developed vegetable production, such as Plovdiv. This will be achieved by using principal component analysis to assess the effects of tomato quality and the efficiency of water use and fertilization.
Study objective – determining the irrigation regime and its influence on the yields of greenhouse tomatoes for the region of the city of Plovdiv

To establish the influence of different irrigation and fertilization rates on the quality indicators of the fruit of three specific genotypes of tomatoes- Maldo, Pink Rock, and Hayet- in 2022, experiments were conducted in the experimental field of Maritza Vegetable Crop Research Institute – Plovdiv in an unheated steel and glass greenhouse type Venlo. The experiment was conducted under three irrigation regimes – optimal, reduced, and increased irrigation – 100%, 75%, and 125% using water-saving irrigation technologies and three fertilization regimes – optimal, reduced, and increased fertilization – 100%, 75%, and 150%.
It was found that reducing the water content resulted in a slight increase in dry matter, total soluble solids (TSS), and vitamin C content while varying the fertilizer rate did not significantly change the studied characteristics. Tomato fruit quality was more affected by irrigation than by fertilizer levels. Titratable acidity and pH differed between cultivars but not between treatments applied. The highest dry matter, TSS, and vitamin C contents were observed in the treatments with low irrigation rates and optimal fertilization (75%W and 100%F). Strong positive correlations were found between dry matter, TSS and vitamin C, while a strong negative correlation was found between fruit firmness and dry matter, TSS and vitamin C.
The factor Genotype had the strongest effect on the tomato fruit quality parameters studied, with a weaker but proven effect of the individual factors irrigation rate and fertilization rate on dry matter, soluble solids content, and vitamin C. The highest fruit quality was found in Pink Rock, followed by Maldo. The variety with the lowest values for most of the quality indicators is Hayet.

To establish the influence of irrigation and mineral regime on the growth index of tomatoes, the irrigation and fertilization schedules of three genotypes of tomatoes grown in an unheated steel and glass greenhouse in an experimental field of MVCRI – Plovdiv, Bulgaria, were examined. Environmentally friendly and water-saving irrigation techniques were used. Different irrigation rates were applied starting from full satisfaction of the crop water requirements to irrigation and with 25% reduction and 25% increase in irrigation rates and three fertilization rates respectively – optimum with 25% reduction and 50% increase.
After processing the results, the growth index showed an increase in the irrigation rate by 25% above the optimum growth in all three tomato cultivars included in the experiment. At the same time, no such relationship was observed when the fertilization rates were changed. The exception was the cultivar ‘Hayet,’ in which a decrease in fertilizer rate was also associated with a higher growth index, close to that of the optimum fertilizer regime. At the same time, the combination of increasing or decreasing the irrigation rate and fertilization did not have a positive effect on growth.

The research was conducted to determine the irrigation regime of greenhouse tomatoes in 2022 on the MVCRI- Plovdiv experimental field in an unheated steel-glass greenhouse of the Venlo type. The experiment was carried out in three irrigation modes: optimal, reduced, and increased, respectively – 100%, 75%, and 125% using water-saving technology.
The size of the irrigation norms has been determined, i.e., the number of waterings for the growing season and their distribution by phases of development for soil and climatic conditions of the Plovdiv region.
The results obtained for irrigation of the greenhouse tomatoes show that 18 waterings were implemented for the growing season to maintain the soil humidity between 85-100% of the MFMC for the conditions of Plovdiv from the beginning of May to the end of July. The size of irrigation norms by modes varies from 14.9 to 24.7 mm, and irrigation from 268 to 447 mm. The maximum irrigation rates during the most significant water consumption period can be applied in 3-4 days and satisfy the needs of the plants. The obtained results are the basis for determining the design irrigation regime and predicting the culture’s irrigation time.

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.

In order to establish the irrigation regime of pepper variety “Gold Medal”, grown in plastic unheated greenhouses in the Chelopechene experimental field, Sofia district, irrigation options were tested from fully satisfying the water needs of the crop /100% irrigation rate/ to irrigation with 20% and with a 30% increase in irrigation rates. A water-saving irrigation technology is used. The highest yield of 4879 kg/dka was obtained when using 130% irrigation rate, followed by the variant with 120% irrigation rate – 4460 kg/dka on average for the research period. The yield in the variant irrigated by class “A” evaporation pan, approaches the yield obtained in the variant with 100% implementation of the irrigation rate.

To determine the evapotranspiration of the pepper, variety “Golden Medal” grown in plastic unheated greenhouses in an experimental test field in Chelopechene, Sofia region, irrigation options were tested from fully satisfying the crop’s water needs to 20% and 30% increased irrigation of irrigation rates and a variant irrigated with 100% irrigation rate. An environmentally friendly and watersaving irrigation technique was used. The evapotranspiration of the culture and the evaporation from a free water surface were experimentally determined. Based on the calculated values of evapotranspiration and evaporation from a free water surface (evaporation) determined by a class “A” evaporation pan, the values of the biological coefficient of the culture in unheated plastic greenhouses were calculated, and the average for the vegetation period of pepper is 1.35.

This is a review of the groups of factors influencing the quality of the main and pre-sowing tillage of the soil for growing tomatoes – soil-climatic, technological.
The paper performs an analysis of the a priori information and from the conducted experimental researches the connection between the separate factors and the quality for performing the basic and pre-sowing treatment of the soil for growing tomatoes was established.

Irrigation plays a key role in growing vegetable crops. The efficiency of irrigation is expressed in obtaining optimal yields in terms of quantity and quality. The use of water resources should be water and energy saving in order to reduce the costs of vegetable production and to be environmentally friendly. The main criteria for assessing the effectiveness of irrigation are the total and additional net incomes. In order to meet the set requirements for irrigation, the best effect is obtained by applying drip irrigation. When growing tomatoes, the value of the irrigation system is redeemed in the first year for areas over 5 dka, for areas below 5 dka it takes 2 years. Drip irrigation of tomatoes has shown that the frequency and size of irrigation rates affect the weight, diameter and length of the fruit, their number and hardness.

The evapotranspiration of Gergana long-fruit cucumbers was established in four years of field experimentation with drip irrigation, grown in greenhouse conditions on chromic luvisol soil in the Sofia region. Different irrigation regimes have been tested – from full satisfaction of the daily needs of the culture from water to irrigation with 20% and 40% reduced water application rates. The total evapotranspiration values for the study period were determined.
For the needs of practice and design, the ten-day values of the biophysical coefficient Z are calculated, which depends on the biological characteristics of the crop and the weather factors. On the basis of the established relationship between evapotranspiration and evaporation, the values of the coefficient of crop in unheated plastic greenhouses are calculated as the average for the cucumber vegetation curve Ki = 1.46.