PLANT PHYSIOLOGY

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PLANT PHYSIOLOGY

• DEFINITION
• Sub-discipline of botany
  which deals with the functioning and physiology
  of plants.

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Contd

• AIMS
• To study chemical and physical processes
  associated with life as they occur in plants.
• At the small scale like molecular interactions in
  photosynthesis, internal diffusion of water,
  minerals and nutrients.
• At large scale like processes of development,
  seasonality, dormancy etc.

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HISTORY OF PLANT PHYSIOLOGY

• Sir Francis Bacon published one of the first
  plant physiology experiments in 1627 in the
  book, Sylva Sylvarum. 
• Jan Baptist van Helmont published what is
  considered the first quantitative experiment in
  plant physiology in 1648.
• In 1699, John Woodward published experiments on
  growth of spearmint in different sources of
  water. He found that plants grew much better in
  water with soil added than in distilled water.

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ROLE OF PLANT PHYSIOLOGY IN AGRICULTUTRE

• Mineral nutrition
• Photoperiodism and Vernalisation
• Production Physiology
• Photosynthesis
• Growth Regulators
• Seed Dormancy
• Tissue Culture

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STAGES OF SEED FORMATION

• GAMETOGENESIS
• POLLINATION
• FERTILIZATION
• DEVELOPMENT OF SEED

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STAGES OF SEED DEVELOPMENT

• HISTO-DIFFERENTIATION
• CELL EXPANSION
• DEHYDRATION

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SEED STRUCTURES

• SEED COAT
• Function
• Dessication
• Mechanical injury
• Environmental fluctuations

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HILUM
SOYBEAN
BEAN
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• ARILLATE
• ARIL
• CARUNCLE
• STROPHIOLE
• OPERCULUM
• MUCILAGE
• MICROPYLE
• CHALAZA

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TYPES OF FRUIT

• 1. Achene A small, usually single-seeded, dry
  indehiscent fruit, e.g. sunflower.
• 2. Caryopsis A dry, nut-like fruit typical of
  grasses, e. g. a cereal grain. It is an achene
  with the ovary wall united with the seed coat.
• 3. Schizocarp A dry fruit which is separated
  into two or more units at maturity. E.g. Carrot.
• 4. Nut Fruit with thick, hard shell like
  fruit wall. E.g. groundnut.

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Chemical composition of seed

• Carbohydrates
• Starch is a polysaccharide composed of ?-1,4
  glucan with ?-1,6 glucan side chains and serves
  as a source of glucose for the germinating seed.
• Other seeds contain compounds referred to as
  hemi-celluloses which are hetero-polysaccharides
  in nature.

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2. LIPIDS

• Lipids are generally present in the form of the
  glycerides of fatty acids CHB2BO-RB1B
  -CHO.RB2B.CHORB3B, where RB1B, RB2B RB3B may
  be the same or different fatty oleic, linoleic
  and linolenic acids.
• The lipids are founding the seeds both as fats
  and as oils, depending on the relative amounts of
  saturated and unsaturated fatty acids occurring
  in the glycerides.

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3- PROTEINS
According to their solubility in water and salt
solutions protein were classified as follows
Solubility Protein type
In water and salt solution 1. Albumins
In salt solution but very slightly soluble in HB2BO 2. Globulins
Soluble in 70-80 ethanol but not soluble in water or absolute alcohol. 3. Prolamins
Soluble only in acids and alkaline 4. Glutelins