2. Definition- Plant Physiology is a branch of Agriculture which deals with the fundamental processes and
function in plant. Like Photosynthesis, plant Nutrition, Respiration, Plant Hormone, transpiration,
environmental stress Plant water relation etc., are studied under plant physiology.
Physiology
Greek word: Physis = Function
Logos = Science
Plant Physiology can also be defined as, “ the study of processes and functional activity occurring in
Father of Plant physiology- Stephan Hales
Indian father of Plant physiology- Sir J C Bose
3. Historical Background:
Sir Francis Brawn 1627 Published first practical book of Physiology Sylva Sylvarum.
Van Helmont concluded that plants get all their weight from water not from soil
1727: Stephan Hales: considered as a father of plant physiology, for the many experiment in the 1727 in
his book. He published Vegetable Statics an account of his pioneering study on the transpiration growth
and gases exchange of plant.
Hales demonstrated that water from the soil moves up the stems to the leaves where it is loss as water
vapor this process called transpiration.
Julius Von Sachs unified the process of plant physiology and put them together as a discipline Lehburch
der Botanik was the plants physiology bible of that time
4. 1771: J Priestley, Jon Ingenhousez and Jon Senebier demonstrated that plant leaves in light take a
and it equivalent amount of oxygen gives out.
Nicholas de Saussure noted that water is evolved in the process the reversed occur in the dark plants
respired like animal taking up oxygen and emitting CO2
1775: M Malpighi : Described the cycle of substance in plants- the ascending and descending currents.
1800: J Senebier & Saussure argued that Photosynthesis represent the nutrition of Plants with carbon
5. Importance of plant physiology in Agriculture:
1. Production physiology
Production Physiology is essentially concerned with the
factors that influence and control the productivity of plants
grown in groups or stands. It is aimed to understand the
process of capture of solar radiation and its conversion to
plant growth
6. 2. Stomatal Physiology
Stomata fulfill three major functions in the physiology of the plant.
(1) They permit the entrance of CO2 into the green leaf at a rate sufficient to support an adequate
rate of photosynthesis for the normal growth and development of the plant.
(2) They permit the entrance of O2 into the leaf at a rapid enough rate to support an aerobic
respiration sufficient to provide the metabolic needs of the leaf.
(3) If these two were the only functions of the stomata they would fulfill them by remaining
constantly open
7. 3. Stress Physiology
Stress in plants can be defined as any external factor that negatively influences plant growth, productivity,
reproductive capacity or survival. Abiotic stress is defined as the negative impact of non-living factors on
living organisms in a specific environment
8. 4. Nutrio-physiology
Nutrio-physiology is the study of the chemical elements
and compounds necessary
for plant growth, plant metabolism and their external
supply. In its absence the plant is unable to complete a
normal life cycle, or that the element is part of some
essential plant constituent or metabolite
9. 5. Hormonal Physiology
Hormonal Physiology study of Plant hormones affect gene expression and transcription levels, cellular
division, and growth. They are naturally produced within plants, though very similar chemicals are
produced by fungi and bacteria that can also affect plant growth.
10. 7. Seed Physiology
Use of seeds to study the influence of various environmental factors e.g. temperature, moisture,
oxygen, light and other factors on germination and seedling emergence.
11. 8. Tissue Culture (Micro-Propagation)
Micropropagation is the tissue culture technique used for rapid vegetative multiplication of
ornamental plants and fruit trees. This method of tissue culture produces several plants. Each of
plants will be genetically identical to the original plant from where they were grown
12. Scope of Plant Physiology?
Plant physiology has vibrant scope in the field of agriculture. It is very important to know the functions of a
living organism or any of its parts. They also have scope in agriculture fields, medicine, food production
textiles.
Career opportunities for Plant Physiology:
Conduct research in breeding, physiology, production, yield, and management of crops and agricultural
plants or trees, shrubs, and nursery stock, their growth in soils, and control of pests; or study the chemical,
physical, biological, and mineralogical composition of soils as they relate to plant or crop growth.
These physiologists can expect jobs at agricultural industries, manufacturing industries, public and private
sectors
13. Job roles for Plant Physiology:
Plant Physiologist
Research Professor
Horticulturalist
Plant Scientist
Assistant Professor in colleges / universities.
Assistant Pathologist
