CHAPTER IV: PLANT GROWTH, DEVELOPMENT AND REPRODUCTION Flashcards
A property of an organism from the moment of its inception.
Development
A process characterized by growth and differentiation/
organization (morphogenesis) into tissues, organs, organisms.
Development
Development had three interrelated aspects,
namely:
growth, cellular differentiation, and organization.
Plants can not move. The form of the plant body is controlled by the way plant cells expand and alter in shape.
Morphogenesis
The direction in which plant cells divide, and thus the direction in which the plant itself grows, is ultimately governed by the plant cell wall.
Morphogenesis
an irreversible time change generally accompanied by an increase in size, weight or mass.
GROWTH
- quantitative aspect
- changes in size (wt/ht)/time.
-Characterized through an S-curve
or sigmoid curve
Growth
There is increase in size due to:
✓ Cell division
✓ Cell enlargement
✓ Change in cell density
Measurements of Growth can be measured in terms of:
✓ Increase in length or growth – in case of stem
and roots.
✓ Increase in area volume/leaf area – in case of
leaves and fruits.
✓ Increase in the number of cells – in algae, yeast
and bacteria
What are the phases of plant growth?
Lag phase
Log phase or Exponential phase
Maturity or Diminishing Growth Phase
Stationary (adult) Stage
Senescence Stage
-the beginning of the growth process
- the rate of growth is generally low
- cell division by mitosis takes place very actively
but there is no increase in cell size.
Lag phase
- the highest growth rate
- increase in the number of cells by mitosis
- cell size increases by absorbing water and
addition of protoplasmic substances.
Log phase or exponential growth
- growth rate is low
- cells achieve the optimum size (adult) and there
is no more increase in size of cell - a little cell division to replace damaged cells
Maturity or Diminishing Growth Phase
- growth rate is zero
- cells still divide to replace damaged/dead cells
Stationary (adult) Stage
- growth rate is negative because of loss of tissues
due to aging process. - finally, the death of the organism.
Senescence Stage
is the process by which a
less specialized cell becomes
a more specialized cell type.
Cellular Differentiation
Cells derived from meristems and cambium differentiate and mature to perform specific functions are termed______
differentiation
orientation and integration of differentiated
cells in space together with regulated growth with
the consequent attainment of form and structure of
the complete organism.
Organization
What are the growth stages of rice ?
Germination
Seedling
Tillering
Maximum tillering
Panicle initiation
Flowering
Harvest
_______do exist. Plant use ______ as an adaptation to escape or minimize injury from harmful external factors or move towards scarce resource or otherwise secure food.
Plant movements
movements
the primary root moves downward
where it can obtain water and mineral nutrients from deep
down while the shoot moves upward to be exposed to light
from the sun.
Plant movements
may exhibit movement of some organs in response
to environmental stimuli.
Plant Movements
What are three steps of plant movements?
Perception
Transduction
Response
It involves recognition of the environmental stimulus by the plant.
Perception
It involves biochemical and biophysical changes which occur in response to perceived stimulus.
Transduction
It shows the changes in the organ affected by the perceived stimulus.
Response
What are the plant movement categories ?
- Tropic Movement (tropisms)
- Nastic Movement
The direction of the environmental stimulus determines
the direction of the movement.
Tropic Movement (tropisms)
What are the kinds of Tropism
phototropism
geotropism/gravitropism
chemotropism
thigmotropism
hydrotropism
Is tropism movement caused by stimulus of light.
Example the tip of plant that lies in room will bend to direction of incident light.
Phototropism
Is tropism movement that follows earth
gravitational force.
Geotropism/Gravitropism
Types of Geotropism/Gravitropism
Positive geotropism
Negative geotropism
______movement with downward direction.
______ movement with upward direction
Positive geotropism
Negative geotropism
Is tropism movement that is caused by chemical substances stimulus. Roots grow toward useful minerals in the soil but away from acids.
Example: the movement of root to food/fertilizer substance in soil.
Chemotropism
Is tropism movement that is caused by stimulus of touch to harder thing.
Example: Tendril of plants.
Thigmotropism
Is a change in the growth of a plant in response to water.
Hydrotropism
Is plant movement to stimulus, that its direction is not determined by stimulus but by plant itself
Nastic movement
What are the kinds of Nastic movement
- photonasty
- nictinasty
- thigmonasty
- thermonasty
- complex nasty
Is nasty movement that is caused by stimulus of
light.
Example: the opening of Mirabilis jalapa (four
o’clock) flower at certain time.
Photonastic
is nasty movement that is caused by dark condition
or induced by diurnal variations in light and temperature.
- Example:
❖ the closing of butterfly flower’s leaves at night.
❖ the closing of compound leaves of Leucaena glauca at
night.
Nyctinasty
Nasty movement that is caused by stimulus of touch or vibration.
Example: the closing of leaves of Mimosa pudica when touched
Thigmonasty/Seismonasty
Is nasty movement that is caused by temperature stimulus.
Example: tulip flower will bloom if subjected to sudden increased temperature.
Thermonasty
Is nasty movement that is caused by several factors altogether
• Example→ the opening and closing of stomata
is influenced by light, chemical substance and water
Complex nasty
______are changes that help a plant species survive in its environment.
Plant adaptations
What are the different Plant Adaptations?
- Morphological adaptations
- Physiological adaptations
- Biochemical adaptations
____ exemplified by the presence of metamorphosed or specialized organs which performs non-typical functions.
Morphological Adaptations
examples: modified roots of certain tree species in marshes which serves as “breathing” organs, thick waxy leaves/stem (dessert plants), thorns for defense, etc.
Morphological Adaptations
exemplified by closing of stomates of many bromeliads (CAM plants) during the day to help conserve water as well as the abscission of leaves in deciduous plants to reduce the evaporative surface area thereby conserving moisture.
Physiological Adaptations
____biochemical changes with some bearing on certain survival mechanisms such as the increase in proline and ABA and osmolytes in plants during period of moisture stress
Biochemical adaptations
enzymes, compounds, plant hormones: auxin, cytokinin, gibberellin, abscissic acid and ethylene, etc.
Biochemical adaptations
_____have biochemical adaptations that minimize water loss while still allowing photosynthesis to take place in intense sunlight.
C4 and CAM
WHAT ARE THE OTHER CONCEPTS RELATED TO PLANT GROWTH?
Liebig’s Law of Minimum
Blackman’s Theory of Optima and Limiting Factor
Mitscherlich Law of Diminishing Return
also known as the “barrel” concept. If a barrel has staves of different heights, the lowest one sets the capacity of the barrel.
Liebig’’s law of the minimum
Law of limiting factors- Liebig’s law
Who is the father of the fertilizer industry
Justus von Liebig
If one group nutrient is missing or deficient, plant growth will be poor, even in the other elements are abundant.
Law of limiting factorS-Liebig’s law
when a process is conditioned as to its rapidity by a
number of separate factors, the rate of the process is limited by the slowest factor.
Example: rate of the photosynthesis
Blackman”s Law of Optima and Limiting Factors
states that a decreasing marginal productivity as levels of the limiting factor are raised. According to this law, plants cannot grow indefinitely and there is a maximum of production.
Mitscherlich’s Law of Diminishing Returns
When plants had adequate amounts of all but one
limiting element, the growth response was proportional to
the limiting element.
Mitscherlich’s Law of Diminishing Returns
What are the plant growth regulation?
AUXIN
GIBBERELLIC ACID (GA)
CYTOKININ (CK)
ETHYLENE
ABSCISSIC ACID (ABA)
____organic substances other than vitamins and nutrients which are active in very minute amounts.
PHYTOHORMONES
formed in certain part of the plants and which are usually translocated to other sites where they may promote, inhibit or otherwise modify physiological, biochemical and/or morphological processes.
PHYTOHORMONES
A growth promoter and growth retardant
PHYTOHORMONES
generic term applied to growth regulators with the special capacity to promote cell elongation.
AUXIN
naturally occurring auxins are the indole-auxins represented by indole-3- acetic acid (IAA).
Auxin
____ is synthesized from the amino
acid tryptophan in actively growing
tissues. Also produced in mature leaves
and root tips, but in lower concentrations.
indole-3-acetic acid
Give some effects of auxin?
- Promotes cell enlargement and cell division in
the cambium in tissue culture. - Stimulates differentiation of phloem and
xylem - Promotes fruit setting and development
in plants. - Can also delay fruit ripening
- Popularly used as herbicides
Who discovered GIBBERELLIC ACID (GA) and what year ?
Kurosawa, a Japanese plant pathologist in 1928
•Rice plants infected by the fungus __________ (Synonym: Fusarium moniliforme) showed excessive stem elongation.
Gibberella fujikuroi
Symptom is called ‘Bakane’ diseases.
GIBBERELLIC ACID (GA)
Now ___different Gibberellins are available- GA1, to GA80 is available.
80
The most commonly occurring gibberellins is____
GA3
What are the Effects of GIBBERELLIC ACID (GA)?
Stimulates stem elongation
Promotes bolting in long day plants
Promotes fruit set and fruit growth in fruits
are a class of plant growth substances
that promote cell division, or______, in
plant roots and shoots.
CYTOKININ (CK)
cytokinesis
They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence.
CYTOKININ (CK)
major site of CK biosynthesis is at the
root aprical meristem although seeds and
developing leaves have been show
CYTOKININ (CK)
Effects of CYTOKININ (CK)
Regulates morphogenesis in cultured tissues
Delays leaf senescence
Promotes cotyledon and leaf expansion
Promotes nutrient mobilization
the only phytohormone occurring in gas
state.
ETHYLENE
it is an unsaturated hydrocarbon synthesized from the amino acid (primary precursor) in many tissues in response to stress.
ETHYLENE
synthesized in most tissues in response to senescence and stresses.
ETHYLENE
being a gas, it moves by diffusion from the site of biosynthesis.
ETHYLENE
Effects of ETHYLENE
1.Promotes ripening of climacteric fruits
2.Induces epinasty
3.Induces lateral expansion
4.Formation of adventitious roots
5. Enhances flower opening in some species
synthesized from mevalonic acid in
mature leaves particularly in response to
water stress. Seeds are also rich in ABA which
may be imported from the leaves or
synthesized in situ.
ABSCISSIC ACID
_____ is exported from leaves in the phloem. There are some evidences that ______ may circulate to the roots in the phloem and then return to the shoots in the xylem.
ABSCISSIC ACID (ABA)
____ functions in many plant developmental processes, including seed and bud dormancy, the control of organ size and stomatal closure.
ABSCISSIC ACID (ABA)
Effects of ABSCISSIC ACID (ABA)
1.Promotes leaf senescence
2.Enhances stomatal closure
3.Counteracts the effects of gibberellins in germinating cereal grains
