Agriculture Reference
In-Depth Information
systems, but some aggregate systems were open until recently. When drip irrigation
is used (which is most common) overwatering to the extent of 20-30 % is common,
in order to prevent drying of the substrate and salt accumulation. In an open system
this results in an expensive loss of water and fertilizer and a potential source of
nutrient pollution of the environment (for WUE, see box 1; and for FUE, box 2).
Many recent installations are closed systems and this will become mandatory in the
future as nutrient management planning is implemented in many countries. A closed
system requires higher water quality to prevent a build-up of unwanted ions. It also
means that the composition of the nutrient top-up solution has to match nutrient
ratios closely when taken up by the crop. In the past, nutrient top-up has been done
on the basis of electrical conductivity measurement but in the future this may be
replaced by the use of specific ion sensors (Inden et al.
1999
; Gieling et al.
2001
).
According to Papadopoulos et al. (
1999
) and Tüzel et al. (
2001
), there were
no significant differences between open and closed-loop culture systems in tomato
fruit quality due to applying adequate culture practices. Similarly Raviv et al. (
1998
)
found no differences in rose production or quality when comparing open-loop sys-
tems with three different recirculation techniques.
In experiments with
Chrysanthemum indicum
hybrids, carnations (
Dianthus
caryophyllus
),
Gladiolus
hybrids (Leinfelder and Röber
1987
,
1989
,
1991
) and
Gerbera
spp. (Özçelik et al.
1999
) no differences were found in terms of flower
quality between diverse substrates in closed-loop culture systems. Rodriguez et al.
(
2006
) investigated different combinations of media (coarse perlite, medium per-
lite, and pine bark) and containers (polyethylene bags and plastic pots) used in the
production of 'Galia' muskmelons (
Cucumis melo
) and found that fruit yield and
fruit quality were not affected by any combination of media and containers. Simi-
larly, Serio et al. (
2004
) investigated the use of washed disposal of the posidonia
(
Posidonia oceanica
)—a marine species belonging to the
Potamogetonaceae
fam-
ily and found no differences in total yield of cherry tomatoes grown in this substrate
or rockwool.
Plant in Soilless vs. Soil Cultures
Gruda (
2009
) points out that the only reliable way to compare soil with soilless
systems is to place both systems under the most optimal growing conditions for
the same crop. In soilless culture, higher yields and earliness of cropping can be
achieved when compared to soil cultivation. For example Selma et al. (
2012
)
showed that a growth period of 102 d was needed for fresh-cut lettuces (
Lactuca
sativa
) to reach the same maturity stage in soil compared to 63 d in soilless culture.
According to Gruda (
2009
) using SCSs does not automatically guarantees high-
quality vegetables. Numerous studies confirm that SCS enables growers to produce
vegetables without quality loss compared to soil cultivation. An adaptation of the
cultural management to a specific cultural system, as well as the crop requirements,
can further result in improving the quality of the horticultural product.
