Image above of my Chilli seedlings growing on my kitchen window ledge taken yesterday. At present I turn them full
circle square every 24 hours. To the science bit…
Phototropism is most simply defined as:
the growth of plants towards a source of light
source Collins English Dictionary 2009
In more detail it is defined as:
The growth or movement of a fixed organism toward or away from light. In plants, phototropism is a response to blue wavelengths of light and is caused by a redistribution of auxin from the illuminated side to the darker side of the shoot, resulting in quicker growth on the darker side and bending of the shoot toward the source of light. Certain sessile invertebrates also exhibit phototropism.source: The American
Heritage® Science Dictionary 2002
Wikepedia explains it further, but unless you’re a total plant geek like me, you might not wish to read another not Peter definition. Moving swiftly onwards…
In my horticulture/ landscaping everyday life, let me give you three examples [there are many I'm sure] of its relevance or point, if you will, of understanding the definition that is Phototropism.
When I first learnt of Phototropism I was about 6 years old and I was growing plants on the top shelf of my Dads garage. It had the old 1980’s wooden double doors with only 3 windows above them for light and my plants sat on the shelf that ran against the side wall, horizontal from the light source. Everyday was a day for turning and rotating.
To present day, in the simplest, yet possibly still a mildly complex format of explaining; all taller growing plants when lined up in a growers nursery are usually placed in rows of minimum 2/ back to back and then in a line. This results in both plants [in this case a tall shrub/ tree] not receiving equal amount of light on all sides. It therefore causes a slight tendency or leaning of the branches/ stems to the one direction, where the light is strongest. It is in part why generally, almost all trees will tend to have one better side.
In gardens for competition/ show garden terms it is also why getting the plants into their new space to settle, to naturalise and and allow them to turn as soon as is possible is imperative. It is also in part, why I choose by hand select every plant I have ever put into a garden.
Of note: not* to be confused with the definition geotropism.
Also of note: For any science biology teachers or just damn cool techie taller people that may be reading this, might I highly recommend you trial this wee project in the vid below. Really simple. But flippin’ deadly.
Also, also of noted, and me being a total stickler for the fine points the they probably need light to grow line at the end should read they do need light to grow. Another post for another day.