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Water Needs of Sweet Cherry Trees in the Light of Predicted Climate Warming in the Bydgoszcz Region, Poland
The Bydgoszcz region (Poland) is located in an area with a very high demand for supplementary irrigation during the vegetation period of plants. The projected global warming will bring a rise in the water needs of crops, and thus a further increase in irrigation needs. The goal of the study was an attempt to estimate the water needs of sweet cherry trees in 2021–2050 (forecast period) in the region of Bydgoszcz. The years 1981–2010 were adopted as the reference period. The water needs of sweet cherry trees were calculated on the basis of air temperature using the Treder method, in which water needs are equated with the potential evapotranspiration of a given fruit tree species. It was found that in the growing season of the forecast period, the relative diversity of sweet cherries’ water needs was relatively small (7%). The highest variability of monthly water needs was in April, May, and June. The seasonal water needs amounted to 573 mm, with very high monthly water needs noted in July (139 mm) and August (134 mm). A significant trend of the time variability of water needs was calculated only in August. During this month, it is predicted that the water needs will rise by 5 mm in each subsequent decade. These results will be helpful in the design of sweet cherry irrigation treatments.
Water Needs of Willow (Salix L.) in Western Poland
Willows are one of the plants which can be used to produce biomass for energy purposes. Biomass production is classified as a renewable energy source. Increasing the share of renewable sources is one of the priority actions for European Union countries due to the need to reduce greenhouse gas emissions. To achieve the best possible growth of the willow and increase its biomass for fuel, it is crucial to provide optimal water conditions for its growth. The aim of the study was to determine the water requirements of willows under the conditions of the western Polish climate and to verify whether this area is potentially favourable for willow cultivation. The novelty of this paper lies in its multi-year climatic analysis in the context of willow water needs for the area of three voivodships: Lubusz, Lower Silesian, and West Pomeranian. This is one of the few willow water-needs analyses for this region which considers the potential for widespread willow cultivation and biomass production in western Poland. Reference evapotranspiration (ETo) was determined by the Blaney-Criddle equation and then, using plant coefficients, water needs for willow were determined. Calculations were carried out for the growing season lasting from 21 May to 31 October. The estimated water needs during the vegetation season amounted on average to 408 mm for the West Pomeranian Voivodeship, 405 mm for the Lubusz Voivodeship, and 402 mm for the Lower Silesian Voivodeship. The conducted analysis of variance (ANOVA) showed that these needs do not differ significantly between the voivodeships. Therefore, it can be concluded that the water requirements of willows in western Poland do not differ significantly, and the whole region shows similar water conditions for willow cultivation. Furthermore, it was found that water needs are increasing from decade to decade, making rational water management necessary. This is particularly important in countries with limited water resources, such as Poland. Correctly determining the water requirements of willow and applying them to the cultivation of this plant should increase the biomass obtained. With appropriate management, willow cultivation in Poland can provide an alternative energy source to coal.