Successive impact of the nitrogen fertilization of basket willow (Salix viminalis L.) on the canopy architecture in 9

The purpose of the present paper was an assessment of the successive impact of fertilization with nitrogen on the regrowth dynamics of the shoots of 10 genotypes (three clones and seven varieties) of basket willow (Salix viminalis L.) in the 9th and 10th year of cultivation. In 2008- 2015, mineral nitrogen fertilization was applied in the whole experiment in four doses. The measurements of height and thickness of willow shoots, of the quantity of live and dead shoots in the snag and live and dead snags on the plot were performed in the experiment realized in 2016-2017. Biometric measurements showed that increased mineral nitrogen fertilization in the year of its application intensified shoots growth in height and thickness, yet in the successive impact, in the 9th and 10th year of willow vegetation weakening of shoot regrowth in height and thickness is observed, and the number of live shoots in the snag and live snags on the plot have reduced. In particular, negative successive impact of the nitrogen fertilization on the willow canopy architecture was demonstrated on the objects that were mowed twice in the first 4-year rotation and on the varieties that do not tolerate this treatment