I find the above contrast each morning in our garden. The withering look of flower leaves and buds and leaves covered in dew! It is contrast that brings surprise each morning! There is a wide gap of temperature between the day and night during this season!
The true dew formation is by condensation, when the temperature drops at night and the moisture of the air condenses into liquid droplets on the leaf. The leaves cool down faster the air around it after sunset. The surface of the leaves becomes cooler than the air touching them. When that air reaches its dew point the liquid droplets cover the leaves.
I noticed that on Mondays, leaves did not show water droplets at the edges of leaves and had only dew on the leaf surfaces. I wondered if that was because on Sundays most plants were not watered as the domestic helper would leave at noon!
My experiment was to watch the leaves in the morning with watering some plants and not watering some others. I noticed that those who were watered in the evening had faint cover of dew lesser than those who were watered. The plants which were watered had dew as well as droplets on the edges of the leaf as seen in the second photo.
This gave me a clue that watering had something to do with the dew formation.
I took the help of the Wikipedia to sort out this in my mind. That is when I realised that the water drops at the edges were on account of Guttation. While leaves close their pores at night, roots continue to absorb water from soil which builds up pressure within the stem and branches. The plants relieve the pressure by pushing the excess water through the hydathodes located at the tips and edges of leaves. Unlike the dew that covers the whole leaf, the guttation drops appear only at the edges of leaf!
That clarified for me that the dew on the leaf surface is on account of condensation and the drops on the edges of leaf is due to guttation.
When I noticed that those plants which were not watered in the evening, only had dew on the surface and no water drops or only occasional drops at the edges, I felt even more clear. The third photo is of a rose bush which was watered in the evening, which did not have dew on the leaves, suggesting that guttation is common than condensation during this season.
I was taken back thinking about the mystery in nature, which sustains plant life.
I confess that I had not known this difference until now although I have a large collection of photos with dew and water drops on leaf surfaces and some with only drops at the edges and some others with dew alone on the surface.
I feel grateful for the question in my mind that took me through this journey of discovery!
It reminds me that seeing involves knowing!
M.C.Mathew (text and photo)
No comments:
Post a Comment