plant growth and development after seeding plant .ppt

plant growth

1. unit twounit two
Plant Structure,Plant Structure,
Chemistry, Growth, Chemistry, Growth,
Development, Genetics, Development, Genetics,
Biodiversity, and ProcessesBiodiversity, and Processes
6 Structure of Higher Plants
 
7 Plant Growth & Development
 
7 Plant Growth & Development
 
 
8 Plant Chemistry & Metabolism
9 Genetics & Propagation
10 Cultivated Plants:
Naming, Classifying, Origin,
Improvement & Germplasm
Diversity and Preservation
 
11 Photosynthesis & Respiration
  
12 Water Relations
  
13 Mineral Nutrition
 

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Practical Horticulture 5
th
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By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
tab
Chapter 7 - Plant Growth and Development
Shoot and Root Systems
The root system and the shoot system tend to maintain a balance:
–As the top of the plant grows larger and larger, the leaf area increases
and water loss through transpiration increases. This increased water
loss is made up by water absorption from an increasing root system.
– The enlarging shoot system also requires greater amounts of mineral
that are absorbed by the increasing root system
2

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Practical Horticulture 5
th
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Chapter 7 - Plant Growth and Development
Definitions and Measurements
•Growth can be measured as increases in
fresh weight or dry weight, or in volume,
length, height, or surface area.
•Plant growth is a product of living cells, with
all their numerous metabolic processes.
•We generally think of growth as an
irreversible quantitative changes in plant
volume or dry weight.
3
Plant growth: size increase by cell division and enlargement,
including synthesis of new cellular material and organization of
subcellular organelles.

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th
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Chapter 7 - Plant Growth and Development
Types of Growth:
08/27/25
DMA: Chapter 9 Hartmann's Plant
Science, 4th edition
4
•Primary vs. secondary
growth
–Primary growth:
increase in plant length
due to apical meristem
activity (root & shoot)
–Secondary growth:
increase in plant
diameter due to lateral
meristem activity
(vascular & cork
cambium)

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Practical Horticulture 5
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Chapter 7 - Plant Growth and Development
Types of Growth:
08/27/25
DMA: Chapter 9 Hartmann's Plant
Science, 4th edition
5
•Vegetative vs. reproductive growth
–vegetative growth: early plant growth producing stems,
branches and leaves
–Reproductive growth: plants produce flowers, fruits
and seeds

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Chapter 7 - Plant Growth and Development
Plant shoot growth can be classified as:
1.Determinate growth: after a certain
period of vegetative growth, flower bud
clusters form at the shoot terminals so
that most shoot elongation stops.
2.Indeterminate growth: bear the flower
clusters laterally along the stems in the
axils of the leaves so that the shoot
terminals remain vegetative and the
shoot con
­tinues to grow until it is stopped
by senescence or some environmental
influence. Example: grapevines.
•The determinate, bush-type plants
produce much less vegetative growth
than do the indeterminate type.
6

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Chapter 7 - Plant Growth and Development
Shoot Growth Patterns:
•Annuals, which are herbaceous
(nonwoody) plants, complete their life
cycle (seed to seed) in one growing
season. Example: sunflower
•Biennials, which are herbaceous
plants, require two growing seasons
(not necessarily two years) to
complete their life cycle (seed to seed).
Example: cabbage
–** Most annual and biennial plants flower
and fruit only once before dying.
•Perennials, which are herbaceous or
woody plants, lives for more than two
growing seasons.
7

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Chapter 7 - Plant Growth and Development
Growth curves:
•Growth curve is an S-
shaped or sigmoid curve
obtained when plot growth
against time
•Growth curve phases
–Initial slow growth (lag
phase)
–Rapid growth
(log/exponential phase)
–Slow growth (diminishing
phase)
–Stop growth (stationary or
steady phase)
08/27/25
DMA: Chapter 9 Hartmann's Plant
Science, 4th edition
8

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Practical Horticulture 5
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Chapter 7 - Plant Growth and Development
Annual Plants
9

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Chapter 7 - Plant Growth and Development
Biennial Plants
•Stem growth is limited during
the first growing season.
10
• The plants remain alive but
dormant through the winter.
• Exposure to chilling
temperatures triggers
hormonal changes leading to
stem elongation, flowering,
fruit formation, and seed set
during the second growing
season.

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Chapter 7 - Plant Growth and Development
Perennial Plants
DMA: Chapter 9 Hartmann's Plant
Science, 4th edition
11
In herbaceous perennials, the roots and shoots can remain alive
indefinitely but the shoot system may be killed by frosts in cold-
winter regions or by senescence-inducing factors.
Shoot growth resumes each spring from latent or adventitious buds
at the crown of the plant

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Chapter 7 - Plant Growth and Development
In woody perennials, both the shoot and root system remain
alive indefinitely.
12
• Shoot growth of
temperate zone
plants takes place
annually during
the growing
season, as
indicated by
Figure 9-6,

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Chapter 7 - Plant Growth and Development
Genetic Factors Affecting Plant Growth and Development
•The organism developing by cell division and elongation from the
fertilized egg—the zygote—in every case is under the genetic
control of the genes inherited from the parents at the time of
fertilization.
13
• The genes direct the form and shape of the organism.
• At any given time, some of the organism's genes are
transcriptionally active, while others are silent.
•The control of gene activity depends on :
1. The cell type,
2. Environmental conditions or,
3. The particular stage of development.

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Chapter 7 - Plant Growth and Development
Environmental Factors Influencing Plant Growth and Development
•Light
14
The sun is the source of energy for photosynthesis and
other plant processes,
• Light quality
Wavelengths of 400 to 700 nm are commonly referred to
as visible light or photosynthetic active radiation (PAR)
(the most important to life on earth).

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Chapter 7 - Plant Growth and Development
15
Photomorphogenesis describes several highly
integrated processes:
1. Seed germination in light-sensitive seeds.
2. De-etiolation (the greening of young seedlings when
they emerge from the soil),
3. Stem growth in plants competing for light with other
plants.
• Most photomorphogenesis responses are regulated
by the phytochrome pigment system
Photomorphogenesis

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Chapter 7 - Plant Growth and Development
Photomorphogenesis
08/27/25
DMA: Chapter 9 Hartmann's Plant
Science, 4th edition
16

17. © 2011, 2007, 2002, 1988 Pearson Education, Inc.
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Practical Horticulture 5
th
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By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
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Chapter 7 - Plant Growth and Development
• Phototropism is a photomorphogenic response of
plants to the direction of light.
• A blue light receptor called phototropin is
responsible for sensing the direction of light.
17
• The bending in positive phototropic
responses is due to increased cell
growth on the side away from the light
source. It is believed that the plant
hormone auxin accumulates on the
shaded side, promoting cell expansion
Phototropism

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Chapter 7 - Plant Growth and Development
Other tropic responses (not related to light)
•Gavitropism: (also known
as geotropism) is a turning
or growth movement by a
plant in response to
gravity.
• Thigmotropism: is a directional
growth movement of curvature which
occurs in response to stimulus of
contact

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Chapter 7 - Plant Growth and Development
Photoperiodism is the photomorphogenic response to
seasonal variations in the amount of daylight (Daylength).
•Examples of photoperiodic responses in plants:
1.Flowering
1.Induction of bud dormancy in woody species
1.The formation of vegetative propagules such as bulbs,
tubers, corms, and runners (stolons).
19
Photoperiodism

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Chapter 7 - Plant Growth and Development
• All photoperiodically controlled processes can be categorized
into three basic response types:
20
1.Long-day plants (LDPs);
2.Short-day plants (SDPs); and
3.Day-neutral plants (DNPs
• The designation as a long- or short-day plant is not
based on the absolute length of the day, but rather if the
photoperiodically controlled process is induced only at
daylengths longer or shorter than specific daylength,
called the critical day length (CDL).

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Chapter 7 - Plant Growth and Development
•Long-day plants: A plant with photoperiodically controlled
process that is induced only when the day length is longer
than the CDL.
•Short-day plants: A plant with photoperiodically controlled
process that is induced only when the day length is shorter
than the CDL.
–No direct relationship exists between the response type and the
absolute length of the CDL.
For example:
- Red clover is an LDP with a CDL of 12 hours,
Garden chrysanthemum, which is an SDP with a CDL of 15
hours.
21

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Chapter 7 - Plant Growth and Development
LDP vs SDP
08/27/25
DMA: Chapter 9 Hartmann's Plant
Science, 4th edition
22

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Practical Horticulture 5
th
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Chapter 7 - Plant Growth and Development

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Practical Horticulture 5
th
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Chapter 7 - Plant Growth and Development
Temperature
24
• All plants have optimal temperatures for maximum
vegetative growth and flowering.
• Most temperate-region plants grow between temperatures
of 4°C and 50°C, but these are generally the limits of plant
growth.
- The high temperatures destroy the protoplasm of
most cells;
- At the low temperatures, most plants just fail to grow
because of a lack of cell activity.

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Chapter 7 - Plant Growth and Development
•Low, non-freezing temperatures (0°C to 10°C) are sometimes
used by plants as cues to coordinate growth and
development with the changing seasons.
•Examples of cold-induced processes include:
25
1. Seed germination.
Some seeds require a period of time during which the
seeds are imbibed at low temperatures (stratification)
before germination is possible.
2. Flowering.
The cold induction of flowering is
called vernalization.

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Chapter 7 - Plant Growth and Development
26
3. Dormancy breakage.
The duration required for complete loss of dormancy is
called the chilling requirement.

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Chapter 7 - Plant Growth and Development
•Water: Most growing plants contain about 90 percent
water.
•Dry soil: water losses more than water supply:
–Plants wilted and may eventually die if they cannot recover
enough soil water to regain their turgidity.
–Herbaceous plants may wilt slightly at midday or later on a
bright sunny day but they usually recover during the night.
– While the plant is wilted, the stomata are closed, cutting off the intake
of CO2 for photosynthesis, and thus reducing carbohydrate
manufacture.
– The quality of soil water, as determined by the quantity of minerals
and salts dissolved in the water, is very important to the growth of
plants.

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Chapter 7 - Plant Growth and Development
Water
28
•Most growing plants contain about 90 percent water.
•Dry soil: water losses more than water supply:
–Plants wilted and may eventually die if they cannot recover enough
soil water to regain their turgidity.
–Herbaceous plants may wilt slightly at midday or later on a bright
sunny day but they usually recover during the night.
–While the plant is wilted, the stomata are closed, cutting off the
intake of CO
2 for photosynthesis, and thus reducing carbohydrate
manufacture.
–The quality of soil water, as determined by the quantity of minerals
and salts dissolved in the water, is very important to the growth of
plants.

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Chapter 7 - Plant Growth and Development
Gases
•The two gases most important to the growth of green plants are
1. Oxygen (O
2
) and
2. Carbon dioxide (CO
2
).
29
•Carbon dioxide is the third most abundant gas in the
atmosphere:
Nitrogen is approximately 78%
O
2
is approximately 21%
CO
2 is approximately 0.035%

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Chapter 7 - Plant Growth and Development
•Plants do most of the work to keep our atmosphere in a
favorable balance.
•However: Atmospheric CO
2
rose 20 to 30 ppm during the
1900s. This elevation is believed to be enough to contribute
significantly to global warming.
30
•Global warming results from atmospheric gases,
especially CO
2
, which trap heat at the earth's
surface. The phenomenon is sometimes referred
to as the greenhouse effect.

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Chapter 7 - Plant Growth and Development
Phase Change: Juvenility, Maturation, Senescence
A newly emerged seedling pass through:
1.Embryonic growth
2.Juvenility
3.Phase change (transition phase)
4.Maturity or adult phase;
5.Senescence and
6.Death.
31
•The juvenile phase is characterized by the inability to
reproduce sexually; (cannot flower).
•The duration of the juvenile phase varies from a week or
two up to thirty or forty years in some tree species.

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Chapter 7 - Plant Growth and Development
32

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Chapter 7 - Plant Growth and Development
Aging and Senescence
•The life spans of the different kinds of flowering plants differ
greatly, ranging from a few months to thousands of years.
33
•Olive trees with huge
trunks found in the
eastern
Mediterranean area
are believed to be
several thousand
years.

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Chapter 7 - Plant Growth and Development
•Senescence is considered to be a terminal,
irreversible deteriorative change in living organisms,
leading to cellular and tissue breakdown and death
of
34
1.Annual plants
(population
senescence) and of
2.Individual plants
(whole plant
senescence)
3.Leaves, seeds,
flowers, or fruits
(organ senescence).

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Chapter 7 - Plant Growth and Development
Senescence is usually considered to be due to:
35
1.Inherent physiological
changes in the plant, or
2.Pathogenic attack or
3.Environmental stress.

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Chapter 7 - Plant Growth and Development
REPRODUCTIVE GROWTH AND DEVELOPMENT
•Fruit and seed production involves several phases:
36
1.Flower induction and initiation
2.Flower differentiation and
development
3.Pollination
4.Fertilization
5.Fruit set and seed formation
6.Growth and maturation of fruit and
seed
7.Fruit senescence

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Chapter 7 - Plant Growth and Development
Flower Induction and Initiation
•In some species, the formation of flowers is influenced
by:
•Daylength (photoperiodic effect) and/or
•Low temperatures (vernalization),
•Flowering in most trees have neither response to
daylength nor cold temperatures.
37

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Chapter 7 - Plant Growth and Development
Photoperiodism (Daylength)
•Figure 9-10 demonstrates how a flash of light (or night break) of
sufficient intensity or duration
•Inhibits flowering of a short-day plant.
•Induce flowering of a long-day plant .
38

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Chapter 7 - Plant Growth and Development
This information has been useful to commercial chrysanthemum
growers who grow these short-day plants on a year-round schedule
•When they want the young plants to reach a size adequate
for flowering, the growers use fluorescent lamps over the
chrysanthemum plants (near midnight), each night for one to
four hours, depending on time of year and latitude. This night
break inhibits flowering until the plants reach the desired
height.
•Conversely, when the natural daylight of summer is too long
for chrysanthemum plants to flower, they cover the plants of
proper size with black cloth or plastic each evening about 6
P.M. and remove it in the morning at about 8 A.M. This
shortens the plant's day (lengthens the night) enough to
induce and fully develop the flowers.
.
39

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Chapter 7 - Plant Growth and Development
Pollination
•The anther and stigma may be
in:

1.Same flower (self-pollination),
2.Different flowers on the same
plant (self-pollination),
3.Different flowers on different
plants of the same cultivar
(self-pollination),
4.Different flowers on plants of
different cultivars (cross-
pollination).
40
Pollination is defined as the transfer of pollen from an
anther to a stigma.

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Chapter 7 - Plant Growth and Development
•If a plant is self-fertile, it
produces fruit and seed
with its own pollen.
•If it is self-sterile, it cannot
set fruit and seed with its
own pollen, but instead
requires pollen from
another cultivar.
•Often this is due to
incompatibility, where a
plant's own pollen will not
grow through the style into
its embryo sac (see Figs. 9-
12 and 9-13).
41

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Chapter 7 - Plant Growth and Development
Parthenocarpy
•Parthenocarpy is the formation of fruit
without the stimulation of pollination and
fertilization. Washington Navel orange, and
many fig cultivars.
(Not all seedless fruits are parthenocarpic)
42

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Chapter 7 - Plant Growth and Development
Fertilization
•In the angiosperms the pollen tube grows through
the micropyle opening in the ovule into the embryo
sac and discharges two sperm nuclei (IN each):
1.One unites with the egg (IN) to form the zygote (2N), which will
become the embryo and eventually the new plant.
2.The other sperm nucleus unites with the two polar nuclei (IN
each) in the embryo sac to form the endosperm (3N), which
develops into food storage tissue.
•This process is termed double fertilization.
•The elapsed time between pollination and
fertilization in most angiosperms is about 24 to 48
hours.
43

44. © 2011, 2007, 2002, 1988 Pearson Education, Inc.
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Chapter 7 - Plant Growth and Development
Fertilization

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th
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Chapter 7 - Plant Growth and Development
Fruit and seed development.

46. © 2011, 2007, 2002, 1988 Pearson Education, Inc.
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th
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Chapter 7 - Plant Growth and Development
Fruit and seed development.

47. © 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Practical Horticulture 5
th
edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
tab
Chapter 7 - Plant Growth and Development
PLANT GROWTH REGULATORS
•Plant hormone is a natural substance (produced by the plant itself)
that acts to control plant activities.
– Effective at very low concentration
– massengers
•Plant growth regulators, include plant hormones and other,
nonnutrient chemicals not found naturally in plants but that, when
applied to plants, influence their growth and development.
•There are five traditionally recognized groups of natural plant
hormones: Auxins, Gibberellins, Cytokinins, Ethylene and Abscisic acid.
•Other newly identify plant hormones include: Jasmonic acid, Salicylic
acid and Brassinosteriods.
47

48. © 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Practical Horticulture 5
th
edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
tab
Chapter 7 - Plant Growth and Development
Plant Growth Regulators
#Hormone Role Commercial use(s)
1Auxins Promote stem cell
elongation
Rooting, fruit setting,
herbicide,
micropropagation
2CytokininsPromote cell division Delay senescence,
micropropagation
3Gibberellin
s
Involve in regulating cell
elongation
Increase fruit size,
stimulate flowering in
biennial plants, stimulate
germination and seedling
growth
4Abscisic
acid
Inhibit cell division and
promote dormancy
-
5Ethylene Control fruit ripening and
senescencing
Fruit ripening and
defoliant, harvest aid

49. © 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Practical Horticulture 5
th
edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
tab
Chapter 7 - Plant Growth and Development
Commercial uses