This study investigated the growth and establishment of the six
plant species on the substrate mixtures described above in order to
select best plant species and substrate combination for future phytoextraction
studies. Two of the candidate plant species (i.e., cassava
and potato) were initially cultivated and propagated using
potting mix containing a mixture of peat moss, compost, coarse,
and fine sand (2-1-1-1 ratio) at the University of Melbourne
Glasshouse Complex at an average 24/20 C day/night temperatures,
14 h photoperiod and daily watering.
The first part of the study assessed the germination of the species
that could be grown from seeds. 100 seeds of Indian mustard,
carrot, and sugar beet, and 150 seeds of white lupin were sown
into shallow 30 30 cm planters containing the various biosolids
and mine tailings mixtures mentioned above, with 3 replicates
per substrate combination. For this experiment, two substrates
were used as a control. One was a potting mix containing a mixture
of peat moss, compost, coarse, and fine sand (2-1-1-1 ratio, prepared
at the University of Melbourne Glasshouse Complex). The
second was a Debco Seed Raising & Superior Germinating Mix
(light loosely textured mix). This additional substrate is used
specifically for seed raising (SRB) and contains a balanced mixture
of ingredients to give the ideal combination of moisture retention,
soil aeration and drainage. The pots were carefully watered daily to
100% field capacity in the morning. After 5–7 days, the number of
emerged seedlings was counted and expressed as percent germination.
A qualitative assessment of lupin seedlings was done using
the following criteria: 1 – most healthy seedling, with 2 cotyledons
and full y-expanded leaves, primary and secondary roots present, 2
– chlorotic leaves and cotyledons, primary and secondary roots
present, 3 – late emerging plants 4 – necrotic leaves and roots,
and 5 – dead. In parallel to this seed germination experiment,
two other species, i.e., potato and cassava, were propagated