PHYSIOLOGICAL PROCESSES AND CROP PRODUCTIVITY

1. ASSIGNMENT ON
PHYSIOLOGICAL PROCESSES AND CROP
PRODUCTIVITY
PRESENTED BY- DEEPIKA SAHU
Ph.D. Previous year
Department- Soil Science and Agricultural
Chemistry
College of Agriculture, Raipur
INDIRA GANDHI KRISHI VISHWAVIDYALAYA, RAIPUR
SUBMITTED TO-
Dr. NARENDRA PANDEY
Professor
Agronomy

2. CONTENT
PHYSIOLOGY
PHOTOSYNTHESIS
MECHANISM OF PHOTOSYNTHESIS
LIGHT REACTION
DARK REACTION
DIVERSITY IN DARK REACTIONS
RESPIRATION
GLYCOLYSIS
LINK REACTION
KREB CYCLE
TRANSPIRATION
STOAMATAL OPENEING AND CLOSING
TRANSLOCATION
CROP PRODUCTIVITY
Major determinants of agricultural productivity
Suggestions for policy implications
REFERENCE

3. INTRODUCTION
PHYSIOLOGY-
This word is derived from Ancient Greek word "physis"
meaning 'nature, origin' and "logia" meaning 'study of'. It is
scientific study of functions and mechanisms in a living system.
PROCESS-
Processes are natural event or sequence of events. Example of
physiological processes that occur in living plants are-
PHOTOSYNTHESIS RESPIRATION
STOMATAL OPENING AND CLOSING
TRANSPIRATION
TRANSLOCATION

4. PHOTOSYNTHESIS
It is the process by which green plants and certain organisms
transform light energy into chemical energy. During
photosynthesis in green plants, light energy is captured and
used to convert water, carbon dioxide into oxygen and energy–
rich compounds.

5. PHOTOSYNTHESIS EQUATION:
6CO2+12H2O→C6H12O6+6O2+6H2O
(in presence of light and chlorophyll)
90% of total photosynthesis is carried out by aquatic plants
and 10% by land plants.
According to Van Niel (1930), oxygen comes from water in
photosynthesis.
6CO2 + 12H2S → C6H12O6 + 12S+ 6H2O
(in presence of light and chlorophyll)
Ruben, Hassid and Kamen (1941) used O18 to experimentally
show that O2 in photosynthesis comes from water.

6. MECHANISM OF PHOTOSYNTHESIS
Photosynthesis has two phases that are light reaction and dark
reaction.
Light reaction or Hill reaction is the process of photosynthesis that
converts energy from the sun into chemical energy in the form of
NADPH and ATP.
•The reactions take place on the thylakoid membranes.
•The inside of the thylakoid membrane is called the lumen, and outside
the thylakoid membrane is the stroma, where the light-independent
reactions take place.
•In each cycle of cyclic-ETS 2 ATP (Adenosine triphosphate) and in
non–cyclic ETS 1 ATP + 2NADPH (Nicotinamide adenine dinucleotide
phosphate) are produced.
•Six turns of both ETS will provide assimilatory power to produce one
molecule of glucose.

7. DARK REACTION
Blackman discovered dark reaction. Calvin and Benson gave cyclic
pathway for this, thus dark reaction is called as Calvin cycle or C3-cycle.
First stable product of this cycle is three carbon compound i.e. PGA
(Phosphoglyceric acid).
•The light-independent reaction of photosynthesis are the chemical
reactions that convert carbon dioxide and other compounds into glucose.
•These reactions occur in the stroma, the fluid-filled area of
a chloroplast outside the thylakoid membranes.
•These reactions take the products (ATP and NADPH) of light-dependent
reactions and perform further chemical processes on them.
•Example of C3 plants include sunflower, soybeans, sugarbeet, rice,
wheat etc.
•Dark reactions are dependent on enzyme but light reactions are
dependent on pigments. In dark reaction there are three pathways of CO2
fixation.

8. DIVERSITY IN DARK REACTIONS
•Also known as Hatch and Slack
pathway. Hatch and Slack Astralia
(1967) studied in detail and
proposed pathway of dark reaction
in sugarcane and maize leaves.
•First stable product is 4C
compound (oxaloacetic acid).
•Kranz (Wreath or ring) Anatomy
present in leaves of C4 plants.
Green bundle sheath cells present
around the vescular bundles. Such
chloroplast are dimorphic and large.
•Example of C4 plants- sugancane,
maize, sorghum, bajra,
Amaranthus, Chenopodium etc.

9. •Oleary and Rouhani
discovered CAM-process.
•CAM stands for
Crassulacean acid
metabolism.
•30 ATP and 12 NADPH used
for producing of 1 glucose. It
occur in Crassulaceae family.
•CAM plants exhibit
ecophysiological adaptaion
with xeric habits
(environment with little
water, such as a desert or an
ice- or snow-covered region).
•Example of CAM plants are-
Agave, Aloe, Opuntia,
Bryophyllum, Pineapple etc.

10. RESPIRATION
The process of respiration in plants involve using the sugars
produced during photosynthesis plus oxygen to produce
energy for plant growth.
It is the breaking down of organic substances viz.
carbohydrate, fat and protein into carbon dioxide, water into
energy.
Stages in respiration-
GLYCOLYSIS LINK REACTION KREB’S CYCLE

11. GLYCOLYSIS
Site of Occurance
•Glycolysis - Occurs in cytosol/cytoplasm
•Formation of Acetyl COA - (Link Reaction) Perimitochondrial space
(outer chamber)/Matrix.
•TCA cycle or Kreb's cycle - Matrix of mitochondria & cytosol in
bacteria.
•ETS - Occurs in cristae or inner memberane of mitochondria and
Oxidative phosphorylation - Occrus in Oxysome head (F1 particle)
Glycolysis - EMP (Embden, Meyerhof, Parnas) pathway. 1932.
The glycolysis is common phase for aerobic & anerobic respirations.
Glycolysis involves a series of ten biochemical reactions in cytoplasm.
In glycolysis, neither consumption of oxygen nor liberation of carbon
dioxide take place.
In glycolysis, 1 glucose produces 2 molecules of pyruvic acids (3C) and
2NADH, & 2ATP are generated in glycolysis, which are equal to 8 ATP.

12. GLYCOLYSIS PATHWAY

13. LINK or GATEWAY
REACTION
Here, Acetyl Co-A is a connecting
link between glycolysis and Krebs-
cycle
KREB CYCLE
•It was discovered by H.A. Kreb.
•Kreb cycle begins by formation
of citric acid (TCA Tricaboxylic
acid).
•In Kreb cycle 2C02 3NADH,,
1FADH, & 1GTP (ATP)
produced by each turn of TCA
cycle.

14. Types of transpiration
FOLIAR LENTICULAR (.1-1%)
STOMATAL (80-90%) CUTICULAR (9%)
TRANSPIRATION-
The loss of water in the form of vapor from the
living aerial parts of the plant is known as
transpiration. The principal part of transpiration is
leaf.

15. STOAMATA
Stomata-Stomata are specialized epidermal cells which are distributed
all over leaf surface but in case of terrestrial plants, mainly on lower
surface of leaves. Therefore approximately 97% of transpiration takes
place from the lower surface in such plants. Each stoma (open) has
two kidney (or bean) shaped guard cells. Inner wall of guard cell is
thick and outer wall is thin. These cells are surrounded by epidermal
or subsidiary or accessory cells.
Classification of Stomata :According to the distribution of stomata,
plants are of five categories:
a) Apple and Mulbery type : In such plants, stomata are present on
under surface only.
b) Potato type : More stomata on the lower (or under) surface than on
upper surface.
c) Oat type : Stomata are equally distributed on both surfaces.
d) Water Lily type : Stomata present only on upper surface.
e) Potamogeton type : In such plants stomata are either absent or
functionless. Such plants are most of the submerged aquatic plants.

16. On the basis of daily movement of stomata, Loftfield classified it into
three main groups.
1) Alfalfa type : Such stomata are open throughout the day and night
and are found mostly in thin leaved mesophytes (plant needing only a
moderate amount of water) e.g. pea, bean, radish, mustard etc.
2) Potato type : Such stomata are open throughout day and night except
for a few hours in the evening. e.g. onion plantain, cabbage, pumpkin
etc.
3) Barley type: Such stomata are open only for a few hours during the
day e.g. cereals.
Continued…

17. 1) The exudation of sap (water) through hydathodes (structure
present at the tips of veins of leaves) is called guttation.
2) The cause of guttation is root pressure (positive hydrostatic
pressure developed in the xylem ducts of the root system.)
3) Necessary condition for guttation:
i)Increased absorption of water and decreased
transpiration.
ii)Warm soil & humid or cool atmosphere.
iii)Warm day and cool night (such condition is available in
winter season.)
4) Guttation normally occurs at night.
5) Accumulation of salts at leaf tip or leaf margin of some
plants during winter is due to guttation.
GUTTATION

18. Hydathode :
It is a specialised epidermal cell found at leaf tip or leaf
margin i.e. end of veins and veinlets.
Bleeding
1) The loss of sap (water) from the injured parts of the plant is
called bleeding.
2) The cause of bleeding is root pressure.
Continued…

19. The movement of sucrose and other substances like amino acids around a
plant is called translocation. In, general this happens between where
these substances are made (the sources) and where they are used or
stored (the sink) i.e. from sources in root to sinks in the leaves.
TRANSLOCATION

20. CROP PRODUCTIVITY
It is the quantitative measure of crop yield in given measured
area of field.
Productivity level of agriculture defines as the amount of crops
production (Kg) in per hectare land.
Agriculture productivity =
Total agriculture crop production
Total land area ( hectares)
• The output value may be compared to many different types of
inputs such as labour and land (crop yield). These are called
partial measures of productivity.
• Agricultural productivity may also be measured by total factor
productivity (TFP). This method of calculating agricultural
productivity compares an index of agricultural inputs to an index
of outputs

21. Rice area production and yield during 2017-18
State Area (million ha) Yield (Kg./ha)
West Bengal 5.52 2906
Uttar Pradesh 5.75 2704
Punjab 3.10 4132
Andhra Pradesh 2.21 3733
Odisha 3.71 1972
Chhattisgarh 3.61 1810
Rice area production and yield during 2018-19
State Area (million ha) Yield (Kg./ha)
West Bengal 5.12 2926
Uttar Pradesh 5.81 2283
Punjab 3.07 4366
Andhra Pradesh 2.16 3788
Odisha 3.77 1739
chhattisgarh 3.76 1311

22. Major determinants of agricultural
productivity
• Finances/ credit to agricultural sector
• Input like fertilizers, pesticides
• High yielding variety of seeds
• Farm mechanization
• Rainfall
• Irrigation facilities
• Incentives to farmers
• Minimum support price
• Consolidation of farm holdings
• Awareness campaign/ programme
• Proper transfer of technology

23. Physiology of grain yield in cereals
Leaf growth is important in influencing light interception, crop growth
and yield in cereals. WATSON reported that leaf area and leaf area
duration were the main causes of yield differences rather than
photosynthesis or net assimilation rate. There are some physiological
aspects which affect the grain yield of cereals:
Leaf Area Ratio (LAR)
 The term, Leaf Area Ratio was suggested by Radford (1967).
 LAR expresses the ratio between the area of leaf lamina to the total
plant biomass or the LAR reflects the leafiness of a plant or amount
of leaf area formed per unit of biomass.
 Expressed in cm2 g-1 of plant dry weight.
Leaf area per plant
Plant dry weight
LAR =

24. Leaf Area Duration (LAD)
• To correlate dry matter yield with LAI, Power et al. (1967) integrated
the LAI with time and called as leaf area duration.
• LAD takes into account, both the duration and extent of
photosynthetic tissue of the crop canopy.
• The LAD is expressed in days.
Where:
L1 = LAI at the first stage
L2 = LAI at the second stage,
(t2-t1) = Time interval in days
LAD =
L1+L2
2
x (t2-t1)

25. REFERENCE
Khajuria Sonia and Sakshi. 2015. Agricultural
Productivity in India: Trends, Challenges and
Suggestions. International Journal of Soil Science and
Research. 516-520.
Bugbee Bruce and Monje Oscar. 1992. The Limits of
Crop Productivity. Validating theoretical
estimated and determining the factors that limit crop
yields in optimal environment. BioScience, Vol. 42
(7), Crop Productivity for Earth and Space. pp. 494-
502.