Propagation of plant by means of the so called „Invitro-Method“,
which means by growing terminal and lateral meristemes of selected mother-plants seems to
be no topic for application of micro fog. Growth of the meristemes and rooting of the resulting
plantlets is performed in sterile plastic containers on a special gel-basis which provide
the necessary micro-climate for the delicate plantlets.
Besides that all propagation
containers are stored in climatized rooms to keep the plantlets in the most favorable conditions.
Therefore fogging and the resulting humidification makes no sense during
the first phase of meristemal propagation.
Matching the plant-types the plantlets remain in their plastic containers
till they reach a desired size. Then they are extracted, replanted into a substrate and very
often into the container they will be finally sold. They only need some time for hardening
and growing to the needed size for selling.
From this point in time - replanting from the meristemal container
into plant substrate - the humidification with hovering fog provides a substantial advantage
compared with other methods of watering. The reason is simple - the plantlets, which are
still small and delicate, are extracted from a cosy environment and thrown into "real
life" for further growing. Sprinkling system with their relative large droplets can
either damage the delicate plantlets by their impact or wet the substrate too much so that
the desired aeration of the soil is lowered. If this happens rooting and root growth can
be impaired considerably.
In addition the evenness of humidification across the total growth-area
can be achieved with fogging far easier that with any other system.
As "in-vitro" production is a continuous process - each day
new batches of plantlets are added for hardening and growing while ready plant are removed
for sale - the fogging system must be able to react to the varying needs of production without
high investments and complex controls.
Plantfog developed 1988 together with the largest meristemal
propagator in Austria - Vitroplant in Korneuburg near Vienna, Austria - a process which provides a maximum in efficiency
with relative modest investments and simple control procedures.
For hardening and final
growing of plantlets 24 table spaces are used, each with an area of 2 x 6 m in two levels.
Each level is set up like a miniature glasshouse and enclosed in a tent of plastic sheets
for isolation from room climate.
Practical experiences have shown that two humidification
profiles are totally sufficient for hardening and final growth.
To avoid the effort of controlling humidity individually for each
table - which would be prohibitive in terms of investment - we have developed a method which
we call "Representative Humidity".
All growth tables are supplied with pressurized water by two independent
Each line is connected to a high pressure pump.
The feeder lines to the individual table spaces are provided with
ball valves so that each growing space can be supplied with fog by one or the other pressure
water line. The ball valves are operated manually as switching from one mode to the
other is a rather infrequent task.
To control the two humidity-modes we use only two humidity
feelers which provide, together with two independent interval controls, the desired humidity
levels in the growing tents.
The feelers are connected with cables which are sufficiently long to
be placed in the growing area of a selected (and representative) table.
During the hardening phase - which last some ten days following the
extraction of the plantlets from the meristemal containers - a very high humidity near saturation
is needed - which means 90...95% rel.H.
For the final growth phase a somewhat lower value of some 70% r.H.
According to the current table setting with freshly extracted or already
hardened plantlets the feeder lines are connected to the matching high pressure system.
The tables 1, 2, 6, 9, 10, 11, 12 and 16 have just received freshly
extracted plantlets from the climate box. They require humidity near saturation. This is
controlled and provided for by pump #1. The ball valves for a.m. tables are opened for feeder
line #1 and closed for feeder line #2. The humidity feeler for these tables is placed for
instance on table #6.
Interval control #1 will provide the necessary fogging with the help
of the feeler which prevents over-humidification.
Tables 3, 4, 5, 7, 14, 19, 20 and 24
contain plantlets in the final growth phase. These will receive only 70% r.H. Pump #2 with
its feeder lines operates these tables. Therefore the ball valves for feeder line #2 are
open and for feeder line #1 closed (for secure operation the feeder lines and ball valves
All other tables are currently not in operation and are being prepared
for future tasks. Here both ball valves are closed, no water is lost.
In spite of [or because of] its simplicity this combination of automatic
and manual operation has been running now for more than six years to full satisfaction. For
more details on the system or growing parameters please contact the technical managers Dipl.
Ing. Leonhard and Dr. Färber, Tel. +43-2243-32 698.
Based on the experiences and success with low investments more systems
of similar design have been installed - for instance in the Institute for Agro-Biotechnology
of the University of Vienna, Research Center Tulln or the Research Labs of the Institute
for Pharmakognosis - University Center Althanstraße Vienna.