Re: gibberellin seed treatment
Loren Russell (loren@PEAK.ORG)
Fri, 16 Feb 1996 10:47:15 -0800 (PST)
Demetrios asked about measuring out small amounts of gibberellin
for use in seed treatments. May I refer him to the method described by
Norman Deno. Deno uses moist paper towels for germination studies [of a
vast range of plants], and 1000 ppm GA3 was one of his treatments. He
describes using a folded 2-inch square of towel, "which holds 6 drops of
water". He found that 1 cubic millimeter of powder, described as "the
amount held on the tip of a round toothpick", dissolved in this much
water gave the desired 1000 ppm. This sounds exceptionally crude, but it
works [and Deno, by the way, is a retired chemistry prof]. I don't like
the towelling method for tiny seeds, so I measure 12 drops from an
eyedropper into a porcelein spotting dish [a standard micro lab
accessory, easily obtained from biological supply houses]. I add two
"toothpick units", add seeds and cover the cell with a microscope
coverglass. It's necessary to observe the seeds daily with a lens. When
the seeds swell, or a few start to germinate, I pipette the lot [with an
eyedropper] onto appropriate seed medium.
The only problem with stock solutions is that gibberellins are
not very stable in solution. It appears that the target range of
effective concentrations is not narrow, so an approximate technique like
this can work.
It's noteworthy that gibberellins stimulate seeds of plants from
a wide range of ecological situations. In addition to CPs, a variety of
forest herbs, plants from alpine screes, and even cacti erespond. Deno
suggests that the giberellins are indicators of fungal metabolism, of
consequence to many higher plants
Loren Russell