Effect of irrigation regime on yield and plant growth of 'Sonsation' strawberry grown in an open field in Estonia

Most of the strawberry growers in Estonia use two-rows beds and one drip tape (30 cm spacing between emitters). Since strawberry is grown as a perennial crop in Estonia, plants will grow large and need a lot of water. There has been discussion whether two drip tapes or more dense emitter spacing would ensure more uniform irrigation and better yield considering that most of the soils where strawberries are grown in Estonia have quite good water holding capacity. An experiment was carried out in summer 2020 in a second-year plantation of short-day strawberry. 'Sonsation' plants had been planted in two rows, with plant spacing 35 cm and the space between the beds 100 cm. A single treatment had three replications with 20 plants per replication. Four different irrigation regimes were used: two treatments had one drip tape (1T) and two treatments had two drip tapes (2T); the spacing between the emitters was either 20 or 30 cm. All treatments received the same amount of water, but the irrigation time was different. Soil volumetric water content (VWC), above ground plant dry weight, total yield plant^‑1, average fruit size and percentage of fruit damaged by strawberry mildew were determined. VWC was the highest in 1T20 (0.35-0.43 m³ m^‑3). Compared to 1T30, plant dry weight was significantly higher in all other treatments. The highest yield (843 g) was obtained from 1T20 treatment. Average fruit size of 1T20 was also significantly higher in the 1T20 treatment compared to 1T30. However, the percentage of fruits damaged by powdery mildew was also highest in the 1T20 treatment. Conclusively, one drip tape with spacing between the emitters at 20 cm ensured higher and more uniform soil moisture, higher yield and larger fruit size during three first harvests.