PLANT GROWTH & DEVELOPMENT
TYPES OF GROWTH CURVES
By plotting the size or weight of an organism against time, the growth curves can be obtained.
On the basis of their shapes, these curves can be of
J-Shaped curve & S-Shaped curve.
(a) S-Shaped Curve ::
It is an ‘S’ shaped curve obtained when we plot growth against time .It is also called ‘sigmoid ‘curve. This curve mainly shows four phases of growth-
1.initial slow growth (Lag phase),
2. the rapid period of growth (Log phase)
3. The diminishing phase where growth will be slow
4. Stationary / steady phase where finally growth stops.
(b) J-Shaped Curve ::
It is also known as geometric growth curve.
In this type of growth, the progeny retain the ability to divide and continue to do so.
GROWTH RATE ::
The increased growth per unit time is termed as growth rate.
Thus, rate of growth can be expressed mathematically.
An organism, or a part of the organism can produce more cells in a variety of ways.
The growth rate shows an increase that may be arithmetic or geometrical.
By plotting the size or weight of an organism against time, the growth curves can be obtained.
On the basis of their shapes, these curves can be of
J-Shaped curve & S-Shaped curve.
(a) S-Shaped Curve ::
It is an ‘S’ shaped curve obtained when we plot growth against time .It is also called ‘sigmoid ‘curve. This curve mainly shows four phases of growth-
1.initial slow growth (Lag phase),
2. the rapid period of growth (Log phase)
3. The diminishing phase where growth will be slow
4. Stationary / steady phase where finally growth stops.
(b) J-Shaped Curve ::
It is also known as geometric growth curve.
In this type of growth, the progeny retain the ability to divide and continue to do so.
GROWTH RATE ::
The increased growth per unit time is termed as growth rate.
Thus, rate of growth can be expressed mathematically.
An organism, or a part of the organism can produce more cells in a variety of ways.
The growth rate shows an increase that may be arithmetic or geometrical.
Condition For Growth
Measurement of Growth ::
Growth in plant can be measured in terms of either:
(i) an increase in length or girth as in case of stem and root, or (ii) an increase in weight, or (iii) an increase in volume or area as in case of fruits and leaves respectively.
(iv) An auxanometer (Gr. auxain= "to grow" + metron= "measure") is an apparatus for measuring increase or rate of growth in Plants.
(v) A crescograph is a device for measuring the growth in plants. It was invented in the early 20th century by Sir Jagadish Chandra Bose.
- Water, oxygen and nutrients as very essential element for growth.
- Turgidity of cells helps in extension growth.
- Water also provides the medium for enzymatic activities needed for growth.
- Oxygen helps in releasing metabolic energy essential for growth activities.
- Nutrients are required by plants for synthesis of protoplasm and act as source of energy.
Measurement of Growth ::
Growth in plant can be measured in terms of either:
(i) an increase in length or girth as in case of stem and root, or (ii) an increase in weight, or (iii) an increase in volume or area as in case of fruits and leaves respectively.
(iv) An auxanometer (Gr. auxain= "to grow" + metron= "measure") is an apparatus for measuring increase or rate of growth in Plants.
(v) A crescograph is a device for measuring the growth in plants. It was invented in the early 20th century by Sir Jagadish Chandra Bose.
Differentiation, dedifferentiation and redifferentiation ::
he cells derived from root apical and shoot apical meristems and cambium differentiate and mature to perform specific functions.
• This act of maturation is termed as differentiation.
• During differentiation major changes takes place in their cell wall and protoplasm.
• Differentiated tracheary element cells loose their protoplasm, develop a very strong, elastic lignocellulosic secondary cell walls.
• The living differentiated cells, that by now have lost the capacity to divide can regain the capacity of division under certain condition is dedifferentiation.
• Development of interfascicular cambium and cork cambium from fully differentiated parenchymatous cells is the example of dedifferentiation.
• Cells produced by the dedifferentiated tissues again loose the capacity to divide and mature to perform specific function is called redifferentiation.
Development ::
Plant development is the process by which structures originate and mature as a plant grows. Plants produce new tissues and structures throughout their life from clusters of undifferentiated cells called meristems
Developmental plasticity is a general term referring to changes in neural connections during development as a result of environmental interactions as well as neural changes induced by learning.
Development can also be termed as − growth + differentiation
Development is controlled by intrinsic as well as extrinsic factors.
Intrinsic − Genetic factors and plant growth regulators
Extrinsic − light, temperature, water, oxygen, etc.
he cells derived from root apical and shoot apical meristems and cambium differentiate and mature to perform specific functions.
• This act of maturation is termed as differentiation.
• During differentiation major changes takes place in their cell wall and protoplasm.
• Differentiated tracheary element cells loose their protoplasm, develop a very strong, elastic lignocellulosic secondary cell walls.
• The living differentiated cells, that by now have lost the capacity to divide can regain the capacity of division under certain condition is dedifferentiation.
• Development of interfascicular cambium and cork cambium from fully differentiated parenchymatous cells is the example of dedifferentiation.
• Cells produced by the dedifferentiated tissues again loose the capacity to divide and mature to perform specific function is called redifferentiation.
Development ::
Plant development is the process by which structures originate and mature as a plant grows. Plants produce new tissues and structures throughout their life from clusters of undifferentiated cells called meristems
Developmental plasticity is a general term referring to changes in neural connections during development as a result of environmental interactions as well as neural changes induced by learning.
Development can also be termed as − growth + differentiation
Development is controlled by intrinsic as well as extrinsic factors.
Intrinsic − Genetic factors and plant growth regulators
Extrinsic − light, temperature, water, oxygen, etc.