Summary:

The aim of the study was to attempt to estimate the demand for water for strawberry grown in the Chojnice county depending on expected climate changes. The study takes into account two scenarios (RCP 4.5 and RCP 8.5) for the period 2021-2100. It was found that in the reference period, the total rainfall deficits during the strawberry growing season in the Chojnice county - in the average, moderately dry and very dry years - amounted 31 mm, 127 mm and 192 mm, respectively. The largest monthly rainfall deficit during the strawberry growing season of the reference period occurred in June. The amount of rainfall deficit - in the average, moderately dry and very dry year - was on the level 19 mm, 39 mm and 53 mm, respectively. In the forecast period (2021-2100), the largest monthly rainfall deficits during the strawberry growing season will occur in July. These rainfall deficits under the RCP 4.5 scenario - in a medium, moderately dry and very dry year - will amount 15 mm, 40 mm and 58 mm, respectively. In the light of the RCP 8.5 scenario, rainfall deficits in July will be even higher and may amount to 17 mm, 43 mm and 61 mm, respectively. In the years 2021-2100, an increase in water demand for strawberry is expected. If climate change proceeds according to the RCP 4.5 scenario, this increase in the period April-October (in relation to the reference period) may amount to 50 mm (i.e. 13%). According to the RCP8.5 scenario, the increase in water demand for strawberry may amount to approximately 69 mm (i.e. 18%). The water demand for strawberry in the period April-October - according to the RCP 8.5 scenario - will increase (in relation to the reference period) to the greatest extent in the decade 2091-2100. This increase will amount 108 mm (i.e. 28%). In the light of the RCP 4.5 scenario, the increase in water demand for strawberry for this case may amount to approximately 63 mm (i.e. 16%). There will be no rainfall deficits in strawberry cultivation in April and October. The largest rainfall deficit during the strawberry growing season (May-September) may occur in very dry years (p=10%). This deficit - for the RCP 4.5 and RCP 8.5 scenarios - may amount to 202 mm and 211 mm, respectively. In case of moderately dry years (p=25%), this deficit will be smaller and - for the RCP 4.5 and RCP 8.5 scenarios - it may amount to 129 mm and 135 mm, respectively. An even smaller rainfall deficit may occur in medium years (p=50%). This deficit may - for the RCP 4.5 and RCP 8.5 scenarios - amount to 34 mm and 39 mm, respectively. The linear regression equations determined for the forecast period (2021-2100) show that - for the RCP 4.5 and RCP 8.5 scenarios - the water needs of strawberry in every 10 years will increase in the vegetation season (April-October) by 4.2 mm and by 10.6 mm, respectively.