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

To establish the totals and average daily evapotranspiration of raspberry under the soil and climate conditions in the village of Chelopechene, near Sofia city research was conducted with drip irrigation of plantations with variety “Lyulin” adopting varying irrigation schedules – from fully meeting the daily crop water requirements to reduced depths with 20% and 40%.
The meteorological conditions during the study period have been influenced by the totals and average daily On average, during the research period the magnitude of the total evapotranspiration for the vegetation period of the raspberry is 482 mm, with the highest values reaching 592 mm in the dry 2000.
For the needs of the practice and the design are calculated also the ten-day values of the biophysical coefficient Z and kb, which depend on the biological characteristics of the culture and the meteorological factors.

Berry cultures – strawberries, raspberries, blackberries, blackcurrants, etc. are of great economic importance due to growing demand and high productivity. In general, they are susceptible to droughts and are so demanding for soil moisture, and their growth and yield depend to a large extent on the presence of sufficient soil moisture.
In order to establish the irrigation regime of raspberriesin drip irrigation conditions, field experiments were conducted on the experimental field Chelopechene-Sofia. Irrigation was carried out with a pre-irrigation humidity less than 85% of WHC and variants watered with irrigation rate reduction of 20%, 40% compared to the variant irrigated at 100% of WHC and non-irrigated variant.
Realized irrigation regimes in individual years have had an impact on the yields obtained, with the highest yields being obtained for the irrigated variants with 100% irrigation rate and the lowest in non-irrigated variants. The highest increase in yield was obtained in 2004 (dry), which is with 67% more compared to non-irrigated variants, and the smallest increase of 33% was obtained in the humid 2005.
The analysis of meteorological factors shows that the rainfall in the country is insufficient to satisfy the requirements of plants of soil moisture, and the temperature sums over ten-days periods over the whole vegetation period considerably exceed the respective norms. This requires the use of drip irrigation for the successful production of raspberries under conditions of water deficiency and relatively high temperatures.

The increasing water deficit requires studies to optimize irrigation regimes and water-saving technologies to achieve economy of irrigation water at an acceptable yield level.
In order to establish the irrigation regime in the field of “Chelopechene” Experimental Field, Sofia, there have been researches, examining different regimes – from full satisfaction of the daily needs of culture for water to irrigation with reduced by 20% and 40% water application rates.
On average, over the survey period, the highest yields were obtained with the irrigated wit 100% water applicatipn rate. Reducing the irrigation rate leads to a corresponding reduction in yields and affects the quality of production. The application of regimes of irrigation with reduced iwater applicatipn rates is recommended  only in the case of water deficiency.

In order to establish the aggregate and average daily values of raspberry evapotranspiration in an experimental site in the village of Chelopechene – Sofia, drip irrigation studies were carried out on a replanting variety "Liulin" under different irrigation regimes – from full satisfaction of the daily needs of the culture from water to irrigation with 20% and 40% irrigation norms. The meteorological conditions during the study period showed an influence on the sum of the sum and day-to-day values of the culture evapotranspiration.

On average, during the research period, the total evapotranspiration rate for the raspberry vegetation period is 4730 m3 / ha, with the main part being formed by the irrigation rate – 60% and by rainfall – 40%

For the needs of practice and design, the ten-day values of the biophysical coefficients Z and Kp were calculated over a five-year period.

To determine the irrigation water productivity for raspberries during their cultivation in the soil-meteorological conditions of the area of the village of Chelopechene – Sofia, studies have been carried out with drip irrigation of a plantation with the variety "Lyulin". Various regimes have been studied – from full satisfaction of the daily needs of the culture to water, to irrigation with 20% and 40% reduction in irrigation regulations.

The meteorological conditions during the study period determined the number of irrigations and the size of the irrigation and irrigation norms of the culture.

On average, over the survey period, the highest yields were obtained with the watered with 100% irrigation norm option. The increase in yields resulting from the irrigation is about three times the non-irrigated option in surface drip irrigation.

The highest irrigation water productivity of 4.3 kg of raspberries per cubic meter of water is obtained in variants irrigated with a 40% reduced irrigation rate.