Seed dispersal


Seeds are an essential component of plant reproduction. Majority of the plant populations grow as a result of proper seed dispersal mechanism. If we take a casual walk across a farming field or in a jungle, we can find a variety of seeds, and the colourful pollen being stuck to our clothes. In order for the fertilization of flowering plants to occur, a medium is required. In this case, our clothes act as a medium of transfer of pollen and seeds.  Seeds takes a number of vehicles to move from one area to another. Some of the most common vehicles that transfer the seeds are the wind, rainwater,  animal`s dung and insects. Seed dispersal can also happen through many other media. These vehicles help in the voluntary or involuntary picking up of seeds from one place to another. Imagine if seeds remain undistributed where all the seeds get accumulated in one area;  it leads to severe competition for the seeds to germinate and grow. Competition can occur for their survival needs such as sunlight, water, minerals, and space resulting in the destruction of weaker ones. Seed dispersal is actually a scientific process occur naturally or artificially. Seed dispersal is the process of spread of seeds to the distant locations away from their parent plant. As the plants have very limited mobility, they must rely on a variety of dispersal vectors to spread their propagules to reach the right place. Seed dispersal factors can be both abiotic vectors and abiotic vectors. Abiotic factors include wind, water, and other natural forces, whereas biotic vectors are the living organisms such as birds and animals. A healthy and systematic dispersal of seeds helps the plants to grow and nurture properly. The growth and genetic composition of plants rely on the pattern of seed dispersal and the mechanism through which seeds get dispersed. There are 5 basic mediums of seed dispersal, they are, gravity, wind, water, animals and ballistic mode. 

Table of Contents

 1. Introduction

2. Mechanism  of  Seed Dispersal

3. Methods( vectors) of seed dispersal

   3.1. Long-distance disperse (LDD)  

   3.2. Autochory 

   3. 3 Barochory or Gravity 

   3.4 Ballistic dispersal or Ballochory 

   3.5 Dispersal by allochory 


Mechanism  of  Seed Dispersal

Seed dispersal varies between different types of seeds based on their size, weight, numbers etc. Lighter seeds disperse far away whereas heavier ones might be spread near the parental plant. Winged seeds like drumstick and maple are dispersed through some animals and insects. Light seeds of grasses or hairy seeds of Maida and sunflower are blown along with the wind.  Some seeds are dispersed by water. Spiny seeds having hooks are caught to the bodies of animals and are moved to remote places. Few of the seeds can be dispersed when the fruits burst with a sudden jerk, ultimately the seeds are scattered.


Methods( vectors) of seed dispersal

1. Long-distance disperse (LDD)  is the proportional distance to which the percentage of seeds (1% out of the total number of seeds produced)  travel the farthest distance. This is out of a 99% probability distribution. There are 2 subtypes in LDD, the proportional type ( An average) and the absolute type(This is the actual or literal distance that the seeds spread ).

2. Autochory is an independent seed dispersal mechanism that doesn't involve the help of external vector. This method is not highly favourable becasue, autochory might not spread the seeds to the farther distance. 

3. Barochory or Gravity based dispersal is the one in which the plant uses the gravity for dispersal. It occurs when a heavier fruits fall off from the plant once they are fully ripe. The seeds being burst out of the fruit to enter the soil. 

4. Ballistic dispersal or Ballochory is when the dispersal happens as a result of the seed being forcefully ejected by explosive dehiscence of the fruit.

5. Dispersal by allochory refers to the type of seed dispersal by using some secondary agent or vector. Vectors can be water, wind, animals, birds, insects etc. 






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