Introduction to Plant Nutrition


Nutrition is an essential component help in the growth and survival of all life forms. It is a science dealing with various aspects of nutrients such as the mode of consumption, 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. In the plants, nutrition is unique because of their 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 depend on other plants and animal food sources. Nutrients consumed by plants and animals help in producing energy, promoting the growth and repairing the damaged tissues on a day-to-day basis. As the plants are stationary, they do not move in most cases, but you may 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. 

1. Introduction

2. Basic nutrients

3. Mode of nutrition in plants

4. Steps of Photosynthesis


     4.1 Stage 1: light-dependent reaction 

    4.2 Stage 2: Light-independent or dark reaction 

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. Plants require 17 different elements for their growth and repair. They are, carbon, hydrogen, minerals ( macronutrients) such as nitrogen, phosphorus, potassium, calcium, sulfur, magnesium, carbon, oxygen (O), hydrogen (H).


Mode of nutrition in plants

Nutrition is the mode of food intake by an organism for its survival. Plants require raw materials( nutrients) to prepare the food. In general, there are 2 modes of nutrition, autotrophic and heterotrophic nutrition. Even though the majority of plants are autotrophs, very few of them belong to the heterotrophic population; they are otherwise known as carnivorous plants.


Steps of Photosynthesis

Photosynthesis is the process of producing glucose (an energy source) by utilizing 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, this reaction primarily relies upon the sunlight. Sunlight plays a key role in photosynthesis. The process starts 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 a 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, calling 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 light reaction to convert carbon dioxide into glucose. The conversion of carbon dioxide into glucose occurs through a series of reactions beginning 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