Introduction to Plant Nutrition

Introduction

Nutrition is an essential process to help in the growth and survival of all life forms. It is a science dealing with the mode of consumption of foods, nutritional values of foods and sources of mineral nutrition in plants. Unlike animals, plants do not depend on others for food hence they are autotrophic. Plant nutrition is a  unique phenomenon because of its ability to produce food through photosynthesis. Photosynthesis is a process in which plants use light, carbon dioxide, minerals, and other essential elements to prepare their own food. On the other hand, animals rely on other plants and animals for their food. Nutrients consumed by plants and animals help in producing energy, promoting the growth and repairing the damaged tissues on a day-to-day basis. Almost all the plants are stationary but it is a wonder how can plants get food though they cannot reach for their food. Plants have deeply stuck root system that can fetch water and minerals from many feet underground.  This post takes you through various concepts of plant nutrition.

 

Basic nutrients

Basic nutrients are classified as Carbohydrates, proteins, fats, vitamins, and minerals. However, plants require more minerals, water, carbon, and other trace elements to synthesize their food. On the contrary, animals need more calories, fats, and proteins in addition to the trace elements while plants require 17 different elements for their growth and repair and some of them are; carbon, hydrogen, minerals ( macronutrients) such as nitrogen, phosphorus, potassium, calcium, sulphur, magnesium, carbon, oxygen (O) and hydrogen (H).

 

Mode of nutrition in plants

Nutrition refers to the mode of food intake and the underlying mechanisms of the plant`s survival. Plants require raw materials( nutrients) and water to prepare the food. In general, there are 2 modes of nutrition, autotrophic and heterotrophic nutrition. Even though the majority of plants are autotrophs while a few are heterotrophic population; they are otherwise known as carnivorous plants.

 

Steps of Photosynthesis

Photosynthesis is the process of producing the basic nutrients such as starch (an energy source) with the help of sunlight, water, and carbon dioxide by the plant leaves. The process is mainly led by chloroplasts- a specialized plant cells found in the green parts. There are 2 stages in the photosynthesis, stage-1, and stage-2.

 

Stage 1: light-dependent reaction 

As the name indicates, the light-dependent reaction primarily relies on the sunlight as the sunlight plays a key role in photosynthesis. The process begins when photons from sunlight strike the surface of leaves. The photons excite the chlorophyll (the light-absorbing pigment ) which in turn resulting in the activation of electrons. During photosynthesis, water is split into oxygen and hydrogen ions with the help of chloroplasts. The activated electronics present in leaf travel through the electron transport chain resulting in the accumulation of the hydrogen ions inside the thylakoid membrane. Thylakoid cells are the disc-shaped structures found in the chloroplast. They assist in generating a proton gradient that helps in the formation of ATP( energy). The electrons going through the electron transport chain eventually end up combining with NADP+ to form NADPH. The end result of the light reaction is the release of oxygen, ATP, and NADPH necessary for the light-independent reaction.

 

Stage 2: Light-independent or dark reaction 

As the name suggests, the light-independent reaction does not always require light, however, the term dark-reaction might be misleading as the process can sometimes occur in the presence of sunlight also. The light-independent reaction uses the energy from the light to convert carbon dioxide into glucose. The conversion of carbon dioxide into glucose occurs through a series of reactions starting with 3-ribulose bisphosphate (RuBP) and eventually end up with the same molecule, resulting in glucose production. As the reactions start and end with the same molecule, it is referred to as a cycle,( Calvin cycle). The enzyme rubisco (RuBP carboxylase) is a very important component of this cycle. The chemical equation for photosynthesis reaction is written as 6CO2 + 6H2O (+ light energy) → C6H12O6 + 6O2.

 

Structure of Chloroplast

 

Process of photosynthesis through leaf structures

 

 

Further reading 

1.     

Structure of leaf                                                    

2.

Photosynthesis in higher plants

3.

Carbohydrates

4.

 Structure of plant cells

 

 

Questions

  1. What is photosynthesis?

  2. Why are plants called autotrophs and what type of autotrophs are plants?

  3. Differentiate between light-dependent and light-independent photosynthetic reactions. 

  4. Name the basic nutrients that plant require.

 



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