Front Range Seed Analysts
1992 Seed Forum Volume 6 Number 2
REASONS FOR GA3 USAGE WITH ROSMARINUS OFFICINALIS
AND LAVENDER VERA
Jane Hall and Barbara Atkins
For those who test lavender and rosemary it is evident that satisfactory germination results are difficult to obtain in laboratory conditions. The situation with these two species is made worse by a varied number of problems.
one problem is that there are no standard AOSA rules for testing these species. This opens the possibility for any method to be used, resulting in inconsistent test results being reported to the buyer.
These species are dormant beyond what is normally seen in germination testing. Normal germinations even with GA range in percentages from the low 30's to 50's. In many states germination percents this low are considered substandard and the seed must be labeled as substandard. This is not a good marketing tool . It is not a matter of trying to establish dormancy in an atypical seed lot, it is a matter of establishing germination of a species.
Tetrazolium testing at the end of the test period is an established method for determining dormancy. This method becomes time consuming and almost impossible when the species in question has a mucilaginous seed coat such is found in rosemary. It is difficult to grasp the seed to cut it and the mucus surrounding the seed tends to interfere with the staining process. Tetrazolium testing at its best is somewhat subjective, but, with the addition of bad cuts and poor staining due to mucus, it becomes a nightmare. Yet it is not enough to just cut the seed and visually inspect the seed for viability either. In rosemary and lavender's case it seems the best indication of viability for the seedsman would be to get the seed to germinate.
To compare rosemary and lavender dormancy and its effect to the grower
to rangegrass dormancy and the way it is used is like
comparing apples to oranges. In rangegrass, dormancy is a valuable
insurance policy against bad weather conditions and poor moisture availability.
Rosemary and lavender are not being planted under adverse conditions, but
rather in green houses under bedding plant conditions. Dormancy percent
is not very valuable to the grower under greenhouse conditions. The grower
needs to know the potential viability of a seed lot and how that may be
achieved. It would be helpful to be able to offer uniformity and consistency
in test results. Ideally, analysts' test information with GA would be of
use to the grower. Maybe we could find a way to make GA usage available
to them in a useful. form.
Copeland wrote in "Principles of Seed Science and Technology" (1976), "It is now agreed that gibberellins are a normal constituent of all green plants as well as seeds. They appear to have a major physiological role during both seed development and seed gemination."
How does the use of GA differ from the accepted practices of using KN03,
ethylene, scarification by sulfuric acid and clipping, and the use of fungicides.
All are approximations of nature, done in the lab by the analyst. A partial
solution to the question of GA use might be to require labeling of seed
tags with treatments used in germination.