The document discusses various aspects of plant growth and development including cell growth, cell division, differentiation, and the role of plant growth regulators. It defines growth and growth rates, and describes the processes of differentiation and dedifferentiation in plant cells. The summary of key points are: 1. Plant growth and development involves processes like cell growth, division, differentiation and is regulated by plant growth regulators. 2. Growth can be arithmetic or geometric, and growth rates can be expressed mathematically. 3. Differentiation is the process by which less specialized cells become more specialized, while dedifferentiation allows cells to regain division capabilities. 4. Plant development results from the complex interactions between growth, differentiation, and

1. Submitted By
PRAVEENKUMAR B
SAJJAN

3. All cells of a plant develops
from the zygote.
Zygote produces a number of
cells which organize into
tissues and organs.
Development is the sum of
two processes: growth and
differentiation.
During the process of
development, a complex
body organisation is formed
that produces roots, leaves,
branches, flowers, fruits, and
seeds, and eventually they
die.

4. Growth may be defined as an irreversible permanent increase in
size , volume or mass of a cell or organ or whole organism.
Growth is one of the fundamental characteristics of a living being.
It is accompanied by metabolic processes i.e. anabolic and catabolic
process, that occur at the expense of energy.
Example:- expansion of a leaf, elongation of stem etc.
GROWTHGROWTH

5. Characteristics of GrowthCharacteristics of Growth
The main characteristics of growth are :-
1.Cellular growth
2.Cell division
3.Cell expansion
4.Cellular differentiation

6. Growth rate can be defined as increased growth per unit time.
The rate of growth can be expressed mathematically.
Types of Growth Rate
Growth RatesGrowth Rates

7. Arithmetic growth -
After mitotic cell division, only one
daughter cell continues to divide
while others differentiate or mature.
Example − root elongating at a
constant rate.
Mathematically, it is expressed as
Lt = L0 + rt
Lt = length at time ‘t’
L0 = length at time ‘zero’
r = growth rate / elongation per
unit time
Constant linear growth, a
plot
of length L against time t

8. Geometric Growth - Initial growth is slow (lag phase), followed by a
rapid increase in growth (log/exponential phase), and followed by a
phase where growth slows down (stationary phase).
Example − all cells, tissues and organs show this type of growth
If one plots the parameter of growth against time, it would be a
typical sigmoid or S- shaped curve.
• The exponential growth can be expressed as :
W1 = W0 ert
W1 = final size (weight, height, number etc.)
W0 = initial size at the beginning of the period
r = growth rate
t = time of growth
e = base of natural logarithms

9. Cellular differentiation is the
process by which a less
specialized cell becomes a more
specialized cell type.
Cells derived from meristems and
cambium differentiate and mature
to perform specific functions
which is termed as
differentiation.

10. Cells undergo structural changes during differentiation.
Changes take place both in their cell walls and protoplasm.
Example :- Cells lose their protoplasm during the formation of
tracheary elements.
Plants develop a strong, elastic, lignocellulosic secondary cell
walls, to carry water to long distances even under extreme
tension.

11. Dedifferentiation is an important biological phenomenon whereby
cells regress from a specialized function to a simpler state reminiscent
of stem cells.
An undividable differentiated cell sometimes regains the power of
division. This process is called dedifferentiation.
Dedifferentiation is a common process in plants during secondary
growth and in wound healing mechanisms.

12. A dedifferentiated cell can
divide and produce new
cells.
New cells produced again
loose the power of division
and become a part of
permanent tissue which is
called “redifferentiation’.
Example:- Formation of
tumour cells.

13. Development is a term that includes all changes that an organism goes
through during its life cycle from germination of the seed to senescence.
Sequence of the developmental process in a plant cell

14. Plasticity – The ability of plant to follow
different pathways and produce different
structures in response to environment and
phases of life.
In cotton & coriander plants, the leaves of the
juvenile plant are different in shape from
those in mature plants.
Heterophylly - The phenomenon of
appearance of different forms of leaves on the
same plant is called heterophylly.
e.g., heterophylly in cotton, coriander .
Heterophylly in
buttercup
(Water Habitat)
Heterophylly in
larkspur
(Terrestrial Habitat)
Plasticity & HeterophyllyPlasticity & Heterophylly

15. Plant growth regulators (Phytohormones) are chemical substances
that influence the growth and differentiation of plant cells, tissues
and organs.
Plant growth regulators function as chemical messengers for
intercellular communication .
They work together coordinating the growth and development of
cells.

18. Auxins were discovered by Charles Darwin and
Francis Darwin.
F.W. Went isolated auxins from the tips of coleoptiles
of oat seedlings.
Went developed Avena curvature test for bioassay of
auxins.
Synthetic Auxins
IAA - Indole Acetic Acid
IBA – Indole Butyric Acid
NAA - Naphthalene Acetic Acid
2, 4-D - 2, 4-dichlorophenoxyacetic

19. promote apical dominance
initiate rooting in stem cuttings
promote flowering e.g. in pineapples
prevent fruit and leaf drop at early stages
promote the abscission of older mature leaves and fruits
induce parthenocarpy, e.g., in tomatoes
used as herbicides
controls xylem differentiation and helps in cell division

20. E. Kurosawa, a Japanese scientist, identified gibbereilins present in
a fungal pathogen Gibberella fujikuroi.
Gibbereilins were isolated from infected rice seedlings when
treated with sterile filtrates of fungus.
 Physiological Effects of GibberelinsPhysiological Effects of Gibberelins
Elongation of intact stems
Dwarf shoots
Bolting in rosette plants (e.g., Henbane, Cabbage)
Overcome the natural dormancy of buds, tubers, seeds etc.
Seed Germination
Induce parthenocarpy or development of seedless fruits
Promote flowering in long day plants
Vernalization

21. Skoog and Miller discovered cytokinins.
Skoog and Miller crystallised the cytokinesis promoting active
substance named it kinetin from corn-kernels and coconut milk.
Physiological Effects of CytokininsPhysiological Effects of Cytokinins
induce cell-division
delay the senescence of leaves and other organs
promotes lateral bud
 increases cell expansion in dicot cotyledons and in leaves
promotes chloroplast devel­opment and chlorophyll synthesis

23. 1963, Frederick T. Addicott and his co-workers identified Abscisic
acid.
ABA was isolated from several abscission-accelerating substances from
cotton plants.
ABA is called stress hormone.
Physiological Effects ofPhysiological Effects of ABA
acts as a general plant growth inhibitor
induces seed and bud dormancy
inhibits seed germination
stimulates the closure of stomata
plays an important role in seed development, maturation and
dormancy

24. Photoperiodism is a response of plants to the relative lengths of light and
dark periods.
Some plants require periodic exposure to light to induce flowering.
Duration of dark period is equally important for flowering.
 Long Day Plants − Plants that require exposure to light for a period
exceeding critical duration to induce flowering.
Example: Pea (Pisum sativum), Barley (Hordeum vulgare), Wheat (Triticum
aestivum)
 Short Day Plants − Plants that require exposure to light for a period less than
this critical period to induce flowering.
Example: Rice, Jowar, Cotton
 Day Neutral Plants − Plants where there is no correlation between exposure
to light duration and induction of flowering.
Example: cucumber, rose, and tomato

25. Vernalisation is the phenomenon of induction of flowering in
plants by exposure to low temperature.
It prevents precocious reproductive development late in the
growing season, and enables the plant to have sufficient time to
reach maturity.
Example − Biennial plants
These are monocarpic plants that flower and then die in second
season.
Examples :- sugar beet, cabbage, carrot, etc.

26. Factors affecting crop production
1. Climatic
2. Edaphic
3. Biotic
4. Physiographic And Socio Economic
Factors

28. Internal factors
Genetic factors
The increase in crop yields and other desirable characters are
related to Genetic make up of plants
1. High yielding ability
2. Early maturity
3. Resistance to lodging
4. Drought flood and salinity tolerance
5. Tolerance to insect pests and diseases
6. Chemical composition of grains (oil content, protein content
)
7. Quality of grains (fineness, coarseness)
8. Quality of straw (sweetness, juiciness) The above characters
are less influenced by environmental factors since they are
governed by genetic make-up of crop.

29. A. Climatic
B. Edaphic
C. Biotic
D. Phsiographic
E. Socio-economic

30. Nearly 50 % of yield is attributed to the influence of climatic
factors.The following are the atmospheric weather variables which
influences the crop production.
1. Precipitation
2 Temperature
3 Atmospheric humidity
4 Solar radiation
5 Wind velocity
6 Atmospheric gases

31. 1. Precipitation includes all water which falls from
atmosphere such as rainfall, snow, hail, fog and dew.
2. Rainfall one of the most important factor influences
the vegetation of a place.
3. Total precipitation in amount and distribution greatly
affects the choice of a cultivated species in a place.
4. In heavy and evenly distributed rainfall areas, crops
like rice in plains and tea, coffee and rubber in
Western Ghats are grown.
5. Low and uneven distribution of rainfall is common in
dry land farming where drought resistance crops like
pearl millet, sorghum and minor millets are grown.

32. 5. In desert areas grasses and shrubs are common
where hot desert climate exists
6. Though the rainfall has major influence on
yield of crops, yields are not always directly
proportional to the amount of Precipitation as
excess above optimum reduces the yields
7 Distribution of rainfall is more important than
total rainfall to have longer growing period
especially in drylands

33. 1. Temperature is a measure of intensity of heat
energy. The range of temperature for maximum
growth of most of the agricultural plants is
between 15 and 40ºC.
2. The temperature of a place is largely determined
by its distance from the equator (latitude) and
altitude.
3. It influences distribution of crop plants and
vegetation.
4. Germination, growth and development of crops
are highly influenced by temperature.

34. 5 Affects leaf production, expansion and flowering.
6 Physical and chemical processes within the plants
are governed by air temperature.
7 Diffusion rates of gases and liquids changes with
temperature.
8 Solubility of different substances in plant is
dependent on temperature.
9 The minimum, maximum (above which crop growth
ceases) and optimum temperature of individual’s
plant is called as cardinal temperature.

36. 1. Water is present in the atmosphere in the form of invisible water
vapour, normally known as humidity. Relative humidity is ratio
between the amount of moisture present in the air to the saturation
capacity of the air at a particular temperature.
2. If relative humidity is 100% it means that the entire space is filled
with water and there is no soil evaporation and plant transpiration.
3. Relative humidity influences the water requirement of crops
4. Relative humidity of 40-60% is suitable for most of the crop plants.
5. Very few crops can perform well when relative humidity is 80% and
above.
6. When relative humidity is high there is chance for the outbreak of pest
and disease.

37.  From germination to harvest and even post harvest
crops are affected by solar radiation.
 Biomass production by photosynthetic processes
requires light.
 All physical process taking place in the soil, plant
and environment are dependent on light
 Solar radiation controls distribution of temperature
and there by distribution of crops in a region.
 Visible radiation is very important in photosynthetic
mechanism of plants. Photosynthetically Active
Radiation (PAR - 0.4 – 0.7µ) is essential for
production of carbohydrates and ultimately biomass.

38. 0.4 to 0.5 µ - Blue – violet – Active
0.5 to 0.6 µ - Orange – red - Active
0.5 to 0.6 µ - Green –yellow – low active
 Photoperiodism is a response of plant to day length
Short day – Day length is 12 hours (Barley, oat, carrot
and cabbage), day neutral – There is no or less
influence on day length (Tomato and maize).
 Phototropism –– Response of plants to light
direction. Eg. Sunflower
 Photosensitive – Season bound varieties depends on
quantity of light received

39. 1. The basic function of wind is to carry moisture (precipitation) and
heat.
2. The moving wind not only supplies moisture and heat, also
supplies fresh CO2 for the photosynthesis.
3. Wind movement for 4 – 6 km/hour is suitable for more crops.
4. When wind speed is enormous then there is mechanical damage of
the crops (i.e.) it removes leaves and twigs and damages crops like
banana, sugarcane
5. Wind dispersal of pollen and seeds is natural and necessary for
certain crops.
6. Causes soil erosion
7. Helps in cleaning produce to farmers.
8. Increases evaporation.
9. Spread of pest and diseases

40. 1. Co 2 – 0.03%, O2 - 20.95%, N2 - 78.09%, Argon - 0.93%, Others
- 0.02%.
2. Co 2 is important for Photosynthesis, Co2 taken by the plants by
diffusion process from leaves through stomata
3. Co2 is returned to atmosphere during decomposition of organic
materials, all farm wastes and by respiration
4. O2 is important for respiration of both plants and animals while it
is released by plants during Photosynthesis
5. Nitrogen is one of the important major plant nutrient,
Atmospheric N is fixed in the soil by lightning, rainfall and N
fixing microbes in pulses crops and available to plants
6. Certain gases like SO2, CO, CH4, HF released to atmosphere are
toxic to plants

41. Plants grown in land completely depend on
soil on which they grow. The soil factors that
affect crop growth are
1. Soil moisture
2. Soil air
3. Soil temperature
4. Soil mineral matter
5. Soil organic matter
6. Soil organisms
7. Soil reactions

42. 1. Soil moisture
1. Water is a principal constituent of growing plant which
it extracts from soil
2. Water is essential for photosynthesis
3. The moisture range between field capacity and
permanent wilting point is available to plants.
4. Available moisture will be more in clay soil than sandy
soil
5. Soil water helps in chemical and biological activities of
soil including mineralization
6. It influences the soil environment Eg. it moderates the
soil temperature from extremes
7. Nutrient availability and mobility increases with
increase in soil moisture content.

43. 2. Soil air
1. Aeration of soil is absolutely essential for the
absorption of water by roots
2. Germination is inhibited in the absence of oxygen
3. O2 is required for respiration of roots and micro
organisms.
4. Soil air is essential for nutrient availability of the
soil by breaking down insoluble mineral to soluble
salts
5. For proper decomposition of organic matter
6. Potato, tobacco, cotton linseed, tea and legumes
need higher O2 in soil air
7. Rice requires low level of O2 and can tolerate
water logged (absence of O2) condition

44. 3. Soil temperature
1. It affects the physical and chemical processes
going on in the soil.
2. It influences the rate of absorption of water and
solutes (nutrients)
3. It affects the germination of seeds and growth rate
of underground portions of the crops like tapioca,
sweet potato.
4.Soil temperature controls the microbial activity
and processes involved in the nutrient availability
5. Cold soils are not conducive for rapid growth of
most of agricultural crops

45. 4. Soil mineral matter
1. The mineral content of soil is derived from the
weathering of rocks and minerals as particles of
different sizes.
2. These are the sources of plant nutrients eg; Ca,
Mg, S, Mn, Fe, K etc

46. 5. Soil Organic matter
1.It supplies all the major, minor and micro nutrients
to crops
2.It improves the texture of the soil
3.It increases the water holding capacity of the soil
4.It is a source of food for most microorganisms
5. Organic acids released during decomposition of
organic matter enables mineralization process thus
releasing unavailable plant nutrients

47. 7. Soil reaction (pH)
1. Soil reaction is the pH (hydrogen ion
concentration) of the soil.
2.Soil pH affects crop growth and neutral soils
with pH 7.0 are best for growth of most of the
crops
3.Soils may be acidic (7.0)
4. Soils with low pH is injurious to plants due
high toxicity of Fe and Al.
5.Low pH also interferes with availability of
other plant nutrients

48. C. BIOTIC FACTORS
Beneficial and harmful effects caused by other biological
organism (plants and animals) on the crop plants
1. Plants
2. Animals

49. 1. Plants
1. Competitive and complimentary nature among field
crops when grown together
2. Competition between plants occurs when there is
demand for nutrients, moisture and sunlight
particularly when they are in short supply or when
plants are closely spaced
3. When different crops of cereals and legumes are
grown together, mutual benefit results in higher yield
(synergistic effect)
4. Competition between weed and crop plants as
parasites eg: Striga parasite weed on sugarcane crop

50. 2. Animals
1. Soil fauna like protozoa, nematode, snails, and insects
help in organic matter decomposition, while using organic
matter for their living
2. Insects and nematodes cause damage to crop yield and
considered as harmful organisms.
3. Honey bees and wasps help in cross pollination and
increases yield and considered as beneficial organisms
4. Burrowing earthworm facilitates aeration and drainage of
the soil as ingestion of organic and mineral matter by
earthworm results in constant mixing of these materials in
the soils.
5. Large animals cause damage to crop plants by grazing
(cattle, goats etc)

51. D. Physiographic factors:
1. Topography is the nature of surface earth (leveled or
sloppy) is known as topography. Topographic factors
affect the crop growth indirectly.
2. Altitude – increase in altitude cause a decrease in
temperature and increase in precipitation and wind
velocity (hills and plains)
3. Steepness of slope: it results in run off of rain water and
loss of nutrient rich top soil
4. Exposure to light and wind: a mountain slope exposed to
low intensity of light and strong dry winds may results in
poor crop yields (coastal areas and interior pockets)

52. E. Socio-economic factors
1.Society inclination to farming and members
available for cultivation
2.Appropriate choice of crops by human beings
to satisfy the food and fodder requirement of
farm household.
3. Breeding varieties by human invention for
increased yield or pest & disease resistance
4.The economic condition of the farmers greatly
decides the input/ resource mobilizing ability
(marginal, small, medium and large farmers)