VOLUM OMAGIAL - Facultatea de Ştiinţe ale Naturii şi Ştiinţe Agricole

Matei Lucian / Ovidius University Annals, Biology-Ecology Series 14: 185-190 (2010)
No preparation or maintenance works were done
before and after planting the newly established
culture (e.g. fertilization, irrigation, etc).
3. Results and Discussions
The monitoring of the growth and development
of the two willow species used to set up the
experimental culture on the phosphogypsum waste
pile, namely S. alba and S. fragilis, led to surprising
results. Thus, on April 8, 2010, twelve days after the
planting, it was observed that 107 out of the 110
planted cuttings took root and sprouts had developed
on them, while the first two-three leaves had already
emerged in a small number of these cuttings. Three of
the 110 cuttings did not take root and dried out. Two
of these belong to S. fragilis and one to S. alba. On
April 18, 2010, the sprouts on the 107 cuttings
opened and the first leaves emerged. Some of them
even grew three-four cm long shoots. On May 20,
2010, it was observed that of the 107 cuttings that
bore sprouts and shoots only 81 developed normally,
with 5-20 cm long shoots. The other 26 were
stagnating. The same situation was encountered on
June 1, 2010, with the specification that the 81
cuttings with normal development had 10-35 cm long
shoots and some of the 26 stagnating cuttings began
to dry.
We must mention that on the two rows (one with
ditch for the verification of the microclimate
influence and one without ditch, as witness), where
the planting depth was 0.7 meters, only S. fragilis was
used. These two rows registered the highest number
of stagnating cuttings about to get dry. The
conclusion is thus that the planting depth is very
important, the greater the depth, the more chances the
cuttings have to take root and develop normally. By
taking phosphogypsum samples from various depths
and performing humidity analyses, it was observed
that humidity increases directly proportionally with
the depth of the sample. Moreover, by analyzing
samples from the surface of the phosphogypsum (0-5
cm) and those from the bottom of the ditches (40 cm),
it was noticed over a period of several months that
the samples from greater depths contained more
water even though the months when the sample was
collected were poor in precipitations. We specify that
187
no samples for the humidity test were collected in
December 2009 because it rained on the day
scheduled for the sample collection (December 12,
2009). The graph in Fig. 2 presents the variation of
humidity depending on the time and depth for the
sample collection.
Fig. 2. The variation of humidity depending on the
time and depth of the sample collection
This situation explains to a large extent the
surprising presence of certain xerophyte species
alongside hygrophyte ones on the phosphogypsum
waste pile.
In order to make a correct estimation of the
rooting and normal development of the cuttings
depending on species, we will only take into account
the eight rows on which the cuttings were planted at a
depth of one meter (four with ditch for the
verification of the microclimate effect and four
without ditch, as witness). These eight rows include
four rows planted with S. alba and four rows planted
with S. fragilis. The total number of cuttings on these
eight rows is 88, of which S. alba – 44, and S. fragilis
– 44. Of the 44 S. alba cuttings planted on four of the
eight rows, 38 develop normally, while of the 44 S.
fragilis cuttings planted on four of the eight
rows, only 32 develop normally. Though it is
premature to draw pertinent conclusions, we can say
that S. alba seems to be better adapted to the
conditions of the phosphogypsum waste pile,
considering that its percentage of rooting and
development is 86.36%, compared to S. fragilis
whose percentage is 72.72%. Taking these results