Today we will talk about some plant diseases. They are an integral part of our lives. Try to imagine life without our green brothers. We would not have paper, furniture, this incredible natural beauty, and most importantly - oxygen. That is, without plants we would not exist either. Today we’ll talk about a disease called tropism. This is a bending that occurs as a result of a factor (gravity, light, and so on). We will discuss this issue in more detail below.
To begin with, it is important to remember that tropism is not the norm, but a disease. It is necessary to help plants that suffer, of course, if there is such an opportunity.
We propose to proceed directly to the characterization of tropism and the analysis of its varieties. Let's start now.
Tropism
So, tropism is the bending of any part of a plant, from Greek this term translates as "turn". This defect can be caused by a number of factors, which include:
- shine;
- gravity and many others.
Tropism is a process whereby cells grow on one side of a shoot (leaf, stem or other parts of a plant) more quickly. If we decided to characterize this disease, then the first thing to pay attention to is the factor that caused it. For example, take phototropism, which is most often found in our lives. This is expressed as a rotation of the plant or some of its organs in one direction, it is caused by one-way lighting. In this case, two types of phototropism can be distinguished:
- positive (if the plant turns to a light source);
- negative (if the plant turns away from the light source).
As far as phototropism is concerned, Charles Darwin began to study this phenomenon for the first time. He noted that the top of the plant is able to respond to light stimulation, which leads to bending. The response falls on the stretch zone, that is, slightly below the portion that responds to light. This discovery allows us to assert that receptors and cells that respond to irritations are disconnected, which led to thoughts about the existence of hormones that act and are synthesized in different places. Now we propose to consider some varieties of tropism, we met one of them in this section.
Varieties of plant tropism
In this section, we consider the tropism of plants of the most common species. We can distinguish such types as:
- phototropism;
- geotropism;
- chemotropism;
- hydrotropism;
- tigmotropism;
- thermotropism;
- electrotropism.
Now a few words about each species. We have already talked a little about the first. Phototropism is the bending of a plant as a result of unilateral exposure to light. It may not manifest itself in any way if after a long stay in the dark illuminate the plant with bright light.
Geotropism is the bending of the axial organs of a plant in connection with the action of gravity. If the geotropism is positive, then the plant sprouts incorrectly relative to the ground. Chemotropism is caused by the uneven distribution of chemicals in the soil. Hydrotropism is caused by improper water distribution. Tigmotropism is caused by physical exposure (contact, pressure, and so on). Thermotropism occurs under the influence of unilateral exposure to heat, and electrotropism - an electric current.
We also note that hydrotropism and tigmotropism are varieties of chemotropism.
Nastia
The Greek word nasso means a seal or a closure. If tropism is associated with changes in the growth process, it is caused by various factors, then nastias are changes under the influence of stimuli that affect evenly all organisms. These factors include:
- changes in air temperature;
- humidity;
- natural light and so on.
A very good example is the behavior of tulip flowers: when the sun sets, they close, when it rises, they open. This phenomenon is called nictinasties, or sleepy movements.
Taxis
Now a few words about taxis, which are also caused by external factors. This is the movement of the whole living organism. We said that tropisms are divided into positive and negative. We can assign the same classification to taxis. In addition, they can be classified by irritants:
- tigmotaxis;
- phototaxis;
- chemotaxis.
We examined a plant disease such as tropism. We hope the information was helpful!