Soil type significantly affected yields and morphological features as
well as active substances content in roseroot raw material. On an average
air dry matter of rhizomes and roots collected from loess soil was
twice as high as the one obtained fromsandy soil (Table 1), which was
in accordance with Węglarz et al. (2008) results, who observed that
on sandy soil plants formed highly branched rhizome with few roots,whereas on clayey and alluvial soil compact rhizome with numerous
roots of a big diameter. On the other side, average phenylpropanoid content
in raw material collected from loess soil was significantly higher by
1.45 and 0.91 than this obtained from sandy soil, respectively in the
first and the second year of vegetation. In the case of above ground
parts of plants in the first year of vegetation air dry weight of stems on
sandy soil was more than ten times lower in comparison to loess one,
whereas in the following year the opposite tendency was observed
(caused by the producing of higher number of better developed stems).
It is worth mentioning here that leonardite addition caused a significant
increase of roseroot rawmaterial yields, especially on plots with autumn
seed sowing, but yield level was markedly lower than in loess soil. Thus,
sandy soil should be avoided in roseroot culture, unless additional organic
material (such as humic acids from leonardite) is introduced.Many other
studies confirmed positive effects of humic substances on plant physiology
by improving soil structure, fertility and root architecture (Canellas et
al., 2011; Nardi et al., 2009; Trevisan et al., 2010b). The auxinic activity of
these substances, was probably the main biological factor responsible for
the positive effects on roseroot physiology.