Nutrition in Plants

Lesson 1- Nutrition in Plants

Introduction

It’s a part of Biology. In this chapter we will understand about the nutrients in plants.

Let’s begin…..

Food is useful for the survival of the living beings because it serves as a rich source of carbohydrates, proteins, fats, vitamins and minerals required for the supply of energy to carry out necessary life processes, proper growth and development of human body. It also required for the repair of the damaged body parts and to fight diseases. These components of food are known as the nutrients.

Nutrients Food items in which the nutrient is found-

Name of Nutrients	Food items
1.     Carbohydrates	Wheat, Rice, Mango, Melon, Maize, Papaya etc.
2.    Fats	Oil, Milk, Egg, Meat, Fish etc.
3.    Proteins	Egg, Milk, Meat, Fish, Beans etc.
4.    Vitamin A	Milk, Carrot, Mango, Papaya etc.
5.    Vitamin B	Liver, Beans etc.
6.    Vitamin C	Orange, Lemon, Guava, Tomato etc.
7.     Vitamin D	Milk, Egg, Fish etc.
8.    Iodine	Crab, Fish, Salt etc.
9.    Phosphorous	Milk, Beans, Bananas etc.
10.  Iron	Apples, Bananas, Spinach etc.
11. Calcium	Egg, Milk etc.

Nutrition and modes of nutrition

Nutrition – The mode of consumption of food by a living being and its utilization by the body is termed as “Nutrition”.

Modes of Nutrition – There are two modes of nutrition:

1.     Autotrophic mode of nutrition

2.    Heterotrophic mode of nutrition

Autotrophic node of nutrition :
In autotrophic nutrition the living being produces their own food in the presence of simple substance.

The organisms undergoing this mode of nutrition are termed as “autotrophs”{auto means self; trophos means nourishment}.

Example – Plants.

Heterotrophic mode of nutrition:  

In heterotrophic mode of nutrition the living being consumes plants or other animals.

The organisms undergoing this mode of nutrition are termed as heterotrophs (heteros meaning another; trophos meaning nourishment).

For example- human beings, animals.

Classification of Heterotrophic mode of nutrition

Herbivores

The organisms that feed on plants are called herbivores. For example, deer, goat, sheep.

Carnivores

The organisms that feed on other animals are called carnivores. For example, lion, tiger, fox.

Omnivores

The organisms that feed on both plants and animals are called omnivores. For example, bear, and human beings.

Photosynthesis

The process by which plants make their own food in the presence of sunlight, carbon-dioxide present in air, water, minerals and chlorophyll present in leaves is termed as photosynthesis.

                               

•  Plants take up carbon-dioxide from the atmosphere through the tiny pores known as stomata present on the surface of the leaves and surrounded by ‘guard cells’.
•  The process of photosynthesis releases oxygen in the atmosphere during the synthesis of food.
• Plants absorb the water and minerals from the soil with the help of deep penetrated roots inside the soil and transport them to the leaves of the plants where synthesis of food takes place.
• The green pigment present in leaves known as chlorophyll helps the leaves of plant to capture the sunlight that act as the source of energy to carry out the process.
•  After this the chlorophyll holding the cells of leaves in the presence of sunlight, carbon dioxide and water to produce carbohydrates in the leaves and is stored in the plants in the form of energy.

                        

Photosynthesis in algae

• We have often observed the presence of some slimy, green patches in the water of ponds or in stagnant water.
• These green patches arise due to the presence of organisms called algae which contains chlorophyll that is responsible for its green color.
• Due to the presence of chlorophyll algae are capable of preparing their own food by the process of photosynthesis in the same way autotrophic plants do.

                                   

Synthesis of plant food other than carbohydrates

·        We have seen so far that photosynthesis can only provide us with carbohydrates which contain carbon,hydrogen and oxygen. These components of carbohydrates are used to produce other components of food.

·        But nitrogenous substances containing nitrogen, proteins, vitamins and minerals are also a substantial component of food.

·        The second source of food for plants is from soil which contains certain minerals like phosphorous, potassium, nitrogen, magnesium, calcium, Sulphur and many other minerals present in dissolved form. These minerals are absorbed by the plants from soil using the root hairs of plants.

·        The nutrients required by plants in large quantities are called macro nutrients whereas the nutrients required by plants in small quantities are called micro nutrients.

·        Due to this reason the quality of plants depend upon the quality of soil. To get good yield of plants it is necessary to take care of the quality of the soil.

·        Out of the minerals present in soil Nitrogen is a macro nutrient for plants. A lot of nitrogen is present in gaseous form (78%) that cannot be used directly by the plants.

·        This atmospheric nitrogen is converted into nitrogenous compounds and fix them into the soil that is done by the nitrogen fixing bacteria. This nitrogen is taken up by the plants.

·        Therefore, farmers add fertilizers to the soil. These fertilizers enrich the soil with additional nutrients like sodium, potassium, phosphorous, nitrogen that is in turn absorbed by the plants and is used to synthesize other components of food such as proteins and fats.

Parasitic modes of nutrition in plants

·        There are certain plants in nature which do not have chlorophyll and hence cannot produce their own food.

·        These plants uses heterotrophic mode of nutrition to derive food for their survival. Cuscuta (Amarbel) is a yellow tubular plant twisting around the stem and branchesof a tree that does not have chlorophyll and hence cannot make its own food.

                                  

·        They climb on other trees known as host plant and absorb the readymade food. Therefore plants like Cuscuta are known as parasite.

Insectivorous plants

·        Some other species of plants known as insectivorous plants that are capable of trapping insects and digesting them. These plants are known as pitcher plants with its leaf modified as pitcher.

·        The top of the leaf forms a cover which closes or opens the mouth of the modified leaf.

·        The pitcher consists of hair like projections directed downwards.

·        As soon as an insect lands over the pitcher the cover of the pitcher opens to swallow the insect.

·        As soon as the insect gets inside the pitcher the top closes and the insect gets knotted in the hair.

·        The plant then digests the insect with the help of the digestive juices secreted inside the pitcher.

                        

Saprotrophs

•         Some microorganisms like fungi use another mode of nutrition known as saprotrophic mode of nutrition.
• ·        The organisms undergoing this mode of nutrition are known as Saprotrophs.
• ·        These fungal spores are present in air and grow as dark patches on the food items or other items like pickles, leather and clothes during hot, humid or rainy season.
• ·        They sit on dead and decaying matter where they germinate and grow.
• ·        They secrete a digestive juice that convert them to solution and absorbs the nutrients.  

                                        

Symbiotic relationship

·        There are certain organisms that lives together and provides food and shelter to each other. This kind of nutrition is known as symbiotic relationship.

·        This kind of relationship is very important for plants because there are certain microorganisms like fungi that lives in the roots of trees and absorb the nutrients from The fungi in turn help the plants to absorb water and nutrients from the soil required for the proper growth of plants.

·        An example is lichens where a symbiotic relation exists between the alga and fungus.

                                    

The algae contains the green pigment called chlorophyll which helps the algae to produce food which is being provided to the fungi too. In return the fungi protects the algae from drying in sunlight by enclosing it inside. So algae provides food to fungi and in return the fungi provides protection to the algae.

·        Not only fungi, this relation also exists between a bee and a flower. The bee helps the plant in pollination (the process of transfer of seeds of one flower to another that helps in asexual reproduction in plants) whereas the flower provides pollen grains and nectar to the bee.

                

·     The water and the essential nutrients are made available to the alga which contains chlorophyll and hence is capable to synthesize its own food. The food produced by alga is provided to the fungus.

·      But in the recent years addition of manure or nitrogenous fertilizers has enriched the soil with the essential nutrients but has resulted in a decrease in the number of these organisms sharing symbiotic relation with the plants.

·     Atmospheric nitrogen cannot be used by plants for production of food. Therefore bacteria known as Rhizobium present in the roots of gram, peas, moong beans and other legumes converts the atmospheric nitrogen into soluble form that dissolves in soil and can be easily absorbed by plants.

·      But these bacteria cannot make their own food and hence the plants in turn provide them with the shelter and food synthesized by them. They exhibit a symbiotic relationship between them.