Biometric parameters of fruits and seeds of Paulownia tomentosa collected from trees growing in soil and climatic conditions of different geographical locations of Odesa, Zakarpattia (Mukachevo) and Lviv regions of Ukraine, as well as technical and absolute germination, germination energy, mean germination time and weight of 1000 seeds, were studied. The effect of different temperatures on seed germination in soil was evaluated under two temperature regimes. The influence of the duration of pre-soaking on seed germination was also determined. Pre-soaking
of seeds in water and solutions of five different stimulants on germination in soil was also investigated. It has been found that in the conditions of Odesa region, the species formed larger fruits and the seeds were characterized by significant rate and uniformity of germination. Lowering of germination temperature caused a decrease in germination energy, laboratory and absolute seed germination, and increased the mean germination time of seeds. Pre-soaking of seeds increased significantly germination rate and its duration was associated with the parameters: germination energy, technical and absolute germination. Among the three seed collections, the highest technical germination was recorded for seeds from Lviv region. The seeds from Odesa region had the highest germination energy. The seeds were characterized by high germination rate in soil regardless of the geographical location of seed collection under the conditions of Ukraine. The highest germination in soil was found for seeds, collected in Lviv. Temperature during germination significantly affected the germination of seeds in soil. Under the temperature regime of 21 to 25 °C, soil fertility parameters were significantly higher. Pre-soaking of seeds had the highest stimulating effect on further germination of seeds in soil among the studied treatments. Pre-treatment of seeds with germination stimulants had generally a positive effect, increasing germination in soil.
Key words: biometric parameters, germination, pre-soaking, stimulators, temperature regimes, weight of 1000 seeds