The early growth conditions notably relative humidity play an important role in this regard. Recent studies have shown that there is a wide genetic variation in the extent to which this phenomenon occurs. Some plants are just better at switching to dry conditions than others after a prolonged period with high humidity.
Habtamu Giday wondered what the underlying mechanism is that rules whether stomata open or close.
Rubber leaf imprints
To get a closer look at the how the stomata work under various humidity conditions, he used leaves from potted roses, a tube of silicon rubber and a dab of nail polish.
The rose plants were raised under controlled climatic conditions at high and medium relative humidity after which they were exposed to drought conditions. Habtamu Giday took leaf samples from these plants and squeezed a small portion of rubber silicone on the leaves to make a detailed imprint of the leaves and their stomata. He then painted the silicone rubber imprints with a fine layer of clear nail polish to achieve a thin, transparent layer that he could peel off and study under the microscope.
Using this method he could gain insight into which conditions stimulated the stomata to open and close. Habtamu Giday found that the roses grown under high humidity conditions had a higher level of abscisic acid and that the high level of this particular growth hormone persisted even when the plants were subjected to drought conditions.
- Stomatal responsiveness seems to be determined by the long-term level of abscisic acid which, in turn, is affected by the relative humidity during the early growth stages, says Habtamu Giday.
Improving stomatal responsiveness
The next question that came to mind was if it possible to take advantage of the
|Contact: Habtamu Giday Gebraegziabher|