Difference between Senescence and Abscission
Just like other living species plants also grow old and die. Plants also undergo aging, a phenomenon where cell organelle, physio-chemical and cellular changes occur in the plants throughout their life and gradually lead to the death of the plant. People often confuse senescence with abscission but they are entirely different processes. Let us see how Senescence differs from abscission!
Senescence:
Senescence is the process of aging in plants. It refers to all changes that occur in a plant and cause death of cells, tissues and whole plant body. In other words, we can say that senescence is a natural process that slowly causes the death of a living entity. Senescence can occur in different ways, it can affect the whole plant or a single part of the plant.
Types of Senescence
Senescence can be divided into the following categories on the basis of their role in the aging of a plant.
1. Whole plant senescence: It occurs in monocarpic plants which produce flower and fruits only once in their entire life, e.g. rice, wheat, mustard, cabbage, bamboos etc. It affects the whole plant; the plant dies after producing flowers and fruits.
2. Shoot senescence: It occurs in certain perennial plants with underground structures like bulbs, tubers and rhizomes. The shoot which remains above the ground dies each year after flowering but the underground part survives and produces new shoots in the next season, e.g. banana, ginger, gladiolus etc.
3. Sequential senescence: It is found in most of the perennial plants. The tips of the main shoot and surrounding branches keep growing and producing new bubs and leaves but the older leaves and lateral parts like old branches undergo senescence and die, e.g. Pinus, Eucalyptus.
4. Simultaneous or Synchronous senescence: It occurs in the deciduous trees such as elm and maple. The trees shed their leaves in the autumn and produce new leaves in the spring.
Abscission:
Abscission refers to the normal separation of a senescent plant part or organ, e.g. old leaves or ripe fruits. It occurs to shed or separate the unnecessary plant parts or organs. For instance, shedding of old leaves at the base of the petiole which usually occurs during autumn. Abscission is very important for the normal life of a plant. This process seals off the vascular system to prevent water or nutrients loss and also protects the plant from the bacterial or fungal infections.
Based on the above information, some of the key differences between senescence and abscission are as follows.
| Senescence | Abscission |
|---|---|
| It is a process which gradually leads to death of a plant. | It does not cause the death of a plant. It just removes the unwanted, old plant parts. |
| It is associated with aging. | It is not associated with aging. |
| It does not minimize the water or nutrients loss. | It minimizes the water and nutrients loss. |
| It does not protect the plant from bacterial or fungal infections. | It protects the plant from bacterial and fungal infections. |
| It occurs due to the aging related physiological and metabolic changes in the plant. | It helps plants survive in harsh conditions such as drought. |
| It is not a self-pruning process. | It is usually known as a self-pruning process. |
| It helps mobilize the essential nutrients to flowers and convert the flowers into fruits. | It helps divert the water and essential nutrients to the younger or growing parts of the plant. |
| It does not help distribute fruits or vegetative structures all over the plant body. | It helps distribute the fruits and vegetative all over the plant body. |
| Plant parts are removed due to aging. | Unnecessary plant parts are removed for better growth of the plant. |