The Phenolic Compounds in the Young Shoots of Selected Willow Cultivars as a Determinant of the Plants’ Attractiveness to Cervids (Cervidae, Mammalia)

SIMPLE SUMMARY: The presented study examined the phenolic acids, flavonoids and salicylates contents in young, 3-month-old shoots of different willow (Salix spp.) cultivars. The contents of individual compounds were not identical and depended on the cultivar from which they were isolated. Then, the severity of foraging damage by deer to the analyzed willow cultivars was evaluated and correlated with the content of specific compounds from each analyzed group. The quantitative relationships of helicine and salicin from the group of salicylic compounds, and between ferulic, trans-cinnamic and synapinic acid from the group of phenolic acids, can determine the foraging attractiveness of willow shoots to cervids. ABSTRACT: This study examined the phenolic acids, flavonoids, and salicylates contents in young, 3-month-old shoots (including the leaves) of willow (Salix spp.). The cultivars were selected based on experiments carried out previously in Poland on fodder and energy willows. It was found, using the HPLC-MS/MS method, that the willow cultivars analyzed from three experimental plots, contained nine different phenolic acids, five salicylates and nine flavonoids, including four flavanols (quercetin, kaempferol, taxifolin and isorhamnetin), two flavanones (prunin, naringenin), two flavones (luteolin, apigenin) and one flavan-3-ol (catechin). The contents of individual compounds were not identical and depended on the cultivar from which they were isolated. The S. laurina 220/205 and S. amygdalina Krakowianka contained the greatest amounts of phenolic acids. The lowest quantities of these compounds were found in the S. viminalis Tur, S. pantaderana and S. cordata clone 1036. The highest concentration of flavonoids in young stems was found in S. fragilis clone 1043. The S. purpurea clone 1131 contained the highest amounts of salicylic compounds. Based on the results obtained from all experimental plots, it was shown that there is a negative correlation between the extent of browsing damage and the content of helicine and salicin from the group of salicylic compounds. A similar analysis between the phenolic acid concentration and the degree of willow browsing showed a positive correlation, especially between ferulic, trans-cinnamic, and synapinic acid. A negative correlation was found between the concentration of protocatechic acid content and browsing by cervids.