>On 10 Apr 1997, ARhymer wrote (in part):
>> I am a high school biology teacher and I am starting a new botany class for
>> upper-classmen this year. We have a large greenhouse and outdoor garden
>> space. I am in zone 7. I would be interested in any and all suggestions
>> for texts/projects/plants that I could use for this class.
David Hershey suggested many interesting activities for the greenhouse and,
with his usual care and concern, even suggested special pieces of
apparatus: (just part of his reply)
...............>Two useful features to include in a teaching greenhouse are
an intermittent
>mist bench and a photoperiod bench. The mist bench is used for rooting of
>cuttings and seed germination. It requires a solenoid valve, mist nozzles,
>and some sort of time clock to control the mist interval, e.g. 5 sec. on
>every 10 minutes. ..............................
We have a mist bench in our greenhouse which gets a lot of use. For
example, we do a simple experiment with chrysanthemums in which each
student makes two cuttings, treating one with the commercially available
Rootone (contains an auxin hormone) and leaving the other untreated. These
are put in separate containers of moist rooting medium (1 part Pro-Mix : 1
part sand) and kept on the misting bench for 3-4 weeks. We then carefully
remove the soil from each and determine which one forms the most new roots.
[Note: This works better with certain varieties of mums than with others
depending on the amount of auxin that is naturally produced by the
particular variety of mum that is used.] It's very important not to let
these cuttings dry out because initially they don't have roots.
The main point of my message, however, is that we have switched to a
different kind of mister than the timer-controlled one Hershey mentions.
Instead of controlling the mister with a timer we now use a
moisture-sensing switch called "Mist-A-Matic," also available from Hummert.
This is better because timers may not water often enough on a sunny
afternoon and too often on a cloudy day. The Mist-A-Matic has a stainless
steel screen on a lever which rises when dry, turning on the mister. As
the screen fills with water it gets heavier, moves downward and shuts off
the water. Thus watering occurs when (and only when) the cuttings (screen)
begin to dry... a function of the conditions in the greenhouse. Catalog
price is $169.
Dr. David W. Kramer
Department of Plant Biology
Ohio State University at Mansfield
1680 University Drive
Mansfield, OH 44906-1547
(419) 755-4344 FAX: (419) 755-4367
e-mail: kramer.8 at osu.edu
