The estimate of the required amount of water on the growth of five species of Paulownia at the first year of cultivation in a Central Europe

Abstract Needed precipitation or supplied water is not known for mostly hybrids. Therefore, we chose one species Paulownia tomentosa and four hybrids - P. bellissia®, P. Clon in vitro 112®, P. Shan Tong and P. Hybrid 9502. We found out how three types of watering affect their height and thickness increment, amount of leaf biomass and leaf area and if the reaction of plants of these species/hybrids to the amount of water is different. We planted 30 plants of each species/hybrids into plant pots under a shelter. At the end of the growing season, we measured the total heights of the plants, the lengths of the current-year shoots, the stem thicknesses of the current-year shoots, and the distances of the ends of the leaves furthest from the stem in the directions of all four cardinal points. We determined leaves area and their weighed (calculated the projection area of the crown and the leaf area index). Our results showed that, generally, the mean precipitation 50 mm per month in vegetation season seems to be insufficient for optimal growth of Paulownia plants in the first years after planting. Depending on the species, Paulownia Shan Tong seems to grow better under 100 mm per month in vegetation season; Paulownia tomentosa seems to grow better under 150 mm (and more) per month in vegetation season; and the plants of Paulownia Hybrid 9502, P. bellissia® and P. Clon in vitro 112® did not achieve optimal growth (values), no matter which type of watering we used.