Assesment of climatic conditions for Actinidia arguta cultivation in north-eastern Poland

This study analysed the effects of weather conditions on the growth and yield of five cultivars of Actinidia arguta, also called hardy kiwifruit, kiwiberry cultivated during 2005-2014 in the Experimental Garden of the University of Warmia and Mazury in Olsztyn, north-eastern Poland. The following cultivars were studied: 'Figumaja', 'Kijevskaja Gibrydnaja', 'Kijevskaja Krupnoplodnaja', 'Purpurovaja Sadovaja' and 'Sientiabrskaja'. For each cultivar, the following were determined: yielding and the beginning dates of the following phenophases: bud swelling, flowering, fruit setting, fruit maturity and the plant growth stages. For the phenophases, the following values were calculated: mean daily temperature (degrees C), sum of effective temperatures (>5 degrees C and >10 degrees C) and sum of precipitation (mm). Individual phenophases of the analysed cultivars of hardy kiwifruit started in a given year almost on the same dates and demonstrated high year-on-year variety. The largest differences (in four weeks) between the extreme dates were recorded for the fruit maturity of the Actinidia arguta. The differences between the extreme dates of other phases averaged two weeks. Simulated data satisfying the assumptions of the assumed climate change scenarios (GISS model E) were used in order to obtain information about future climatic conditions in which kiwiberry could be cultivated in the region of north-eastern Poland. Using the weather generator WGENK, 300 probable variants of weather sequences were generated in annual periods, which made it possible to examine the probable diversity of future weather conditions. Comparative characteristics of climatic indicators determined on the basis of the data from the 2005-2014 years and the generated data demonstrated that the climatic conditions of the area of north-eastern Poland could be subject to significant change, particularly in thermal resources. Spring frosts, which in the future could be more intense and could emerge much later than now, continue to pose an element of risk related to Actinidia arguta cultivation.