Articles
EFFECT OF A SHORT DURATION TEMPERATURE DROP ON WATER STATUS AND ELONGATION GROWTH OF ORNAMENTAL PLANTS
Furthermore a strong correlation between climatic influences, e.g. temperature, water status and elongation growth exists.
As could be seen in former studies, the effect of a strong temperature drop on water status was obvious by wilting.
Therefore the effect of a short duration temperature drop on water status, particularly considering transpiration, was examined.
With poinsettias, fuchsias and pelargoniums transpiration during and after a 2-hour period with low temperatures was measured porometrically and gravimetrically.
Whilst it turned out that the porometric measurement was not the suitable method for this study, gravimetric measurements showed a strong reduction in transpiration through the cooling period.
Furthermore after-effects occured, because the transpiration was strongly reduced in the following warm period, too.
Comparable to elongation growth the transpiration was more reduced, the lower the temperature was dropped.
With poinsettias a temperature drop to 8 °C reduced the water loss up to nearly 25 %, a drop to 4 °C to about 50 % compared to the uncooled plants.
Beyond a direct retardation of transpiration a reason for the disorder in water status maybe a reduced water uptake caused by low temperatures of the substrate.
Discussed reasons for the elongation retarding effects of a short duration temperature drop, are a reduced turgor pressure and thus a reduced elongation growth, as well as effects on hormonal balance by latent drought stress.