Evapotranspiration in the tomato variety “Nikolina F1”, under conditions of surface drip irrigation and optimal irrigation regime

¹ Nikola Poushkarov Institute of Soil Science, Agrotechnologies and Plant Protection, Agricultural Academy, Department of Agricultural Mechanization and Hydromelorative Systems, Sofia, Bulgaria
² Nikola Poushkarov Institute of Soil Science, Agri-environment and Farming Systems, Agrotechnologies and Plant Protection, Agricultural Academy, Department of Agricultural Chemistry, Sofia, Bulgaria

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

Evapotranspiration (ET) is a key process that significantly affects the water balance and irrigation regime in crops, including tomatoes of the „Nikolina F1“ variety. The present study aims to analyze the change in ET during the growing season of tomatoes under surface drip irrigation, as well as the influence of climatic factors. Special attention is paid to the irrigation rates applied over a period of three years. When growing tomatoes of the „Nikolina F1“variety in field conditions, the total irrigation rate for the growing season (May-September) is within 275-280 mm, with the number of irrigations varying between 14 and 15. The optimal irrigation rate per irrigation for tomatoes under drip irrigation is between 15 and 30 mm, depending on the development phase. In terms of air temperature, the years 2018, 2019, and 2020 are characterized as very warm with a probability of exceeding 1.16% (2018), 4.47% (2019), and 7.78% (2020), respectively. The largest share in the formation of ET is in the dry year 2020. The irrigation rate takes the largest share, with its percentage participation reaching 58%, and precipitation 42%. And in the wet year 2018, the participation in the irrigation rate was 25%. The results show clearly pronounced peaks of the ET in the vegetation period (July-August) and lower values at the beginning and end of the vegetation, with the values of daily evapotranspiration having a direct relationship with the number of irrigations and the applied irrigation.