Wpływ zagęszczenia krzaków wierzby na odrastanie pędów w trzyletnim cyklu jej uprawy

Najważniejszym źródłem energii odnawialnej w Polce jest biomasa, a jej udział w bilansie paliwowym wynosi około 90% [4]. W ostatnich latach znaczenia nabiera biomasa rolnicza, szczególnie z drzew szybko rosnących. Zapotrzebowanie energetyki na biomasę jest bardzo duże - ok. 17,5 mln ton [3]. Wyprodukowanie takiej ilości biomasy każdego roku wymaga opracowania efektywnej technologii jej pozyskiwania, z uwzględnieniem gatunków roślin i odmian, oraz warunków uprawy i zbioru. W Polsce duże nadzieje pokłada się z uprawą wierzby krzewiastej. Ograniczenie nakładów finansowych na jej uprawę, może zachęcić do rozwijania produkcji biomasy stałej z wierzby. Celem pracy była ocena dynamiki odrastania pędów dziesięciu odmian wierzby krzewiastej (Salix viminalis) w trzyletnim cyklu, uprawianych w rejonie Koszalina, na glebie lekkiej, o głębokim poziomie wody gruntowej, zróżnicowanym zagęszczeniu krzaków na hektarze.

This experiment was conducted to assess regrowth of shoots of Salix viminalis in the three-years-cycle of cultivation, of ten varieties of willow, on the light soil, at different density of planting bushes per hectare (15 020, 22 134 and 35 200 pieces). The importance of studied factors on the variability of height, thickness and number of live shoots in bush in order of decreasing main effects was as follows: years of shoots regrowth, time of measurement, varieties and density of planting of willow. Following interactions: years of willow shoots regrowth with varieties and varieties of willow with planting density were important for all features. Increase shoots length were arranged according to the rainfall during the growing season of willows and were highest in 2009, lower in 2010, and the lowest in 2008. The longest shoots were in the objects with density of planting 22 thousand of bushes and the shortest at planting of 15.0 thousand of bushes per hectare. Number of living shoots in the bush decreased with increasing density. On average, the longest and thickest shoots had Ekotur variety, shortest - Start variety, and thinnest - 1054 variety The least living shoots in the bush was found in Oloff variety the most Sprint variety. The longest shoots in all planting densities had Ekotur variety, and the shortest varieties: 1047 at planting 15 020 bushes per hectare, 1054 at planting 22 134 bushes per hectare, and 1047D at planting 35 200 bushes per hectare. The biggest differences of shoot length between the planting densities were observed for Oloff variety, and the smallest - for Start variety. The dynamics of decreasing of number of living shoots between planting densities was different for varieties of willow. The biggest differences in the number of living shoots between the planting densities was observed for 1047D variety, and the lowest - for 1047 variety.