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Minggu, 30 November 2014

Growth and Development Concept & Curve of Plant Growth


PAPER OF PLANT PHYSIOLOGY
PLANTH GROWTH AND DEVELOPMENT
                        (Growth and Development Concept & Curve of Plant Growth)



GROUP 6

        1.     ELLA EKA PUTRI
        2.     RADILA WIDAYATI





BIOLOGY MAJOR
MATHEMATIC AND SCIENCE FACULTY
PADANG STATE UNIVERSITY
2014


PLANTH GROWTH AND DEVELOPMENT

A.    Growth and Development Concept

Growth is a process that is irreversible increase in volume (irreversible), and is due to the increase in the number of cells and enlargement of each cell. In normal growth process is accompanied by a change in shape. Growth can be measured and expressed quantitatively. The development is the process to adulthood. The process of development runs parallel to the growth. In contrast to the growth, development is a process that can not be measured. In other words, the development of a qualitative nature, can not be expressed numerically.
In plants, the growth started from seed germination process. Germination can occur when the water content in the seeds of higher due to the influx of water into the seed through imbibition process. If the process is optimal imbibition, germination begins. The structure of the first to appear, which tore the lining of seeds is radicle who are candidates for primary roots. Radicle is part of the hypocotyl. At the upper end there epikotil (candidate stem). Based on the location of kotiledonnya, there are two types of germination is epigeal type, and the type hipogeal.
Hipogeal germination

          

Epigeal germination

In general, developments in plant growth and begins to stage the embryo is fertilized by the male female sex cells. Cleavage of the zygote produces meristem tissue will continue to divide and differentiate. Differentiation is the change of state of a number of cells, forming organs have different structures and functions. Seeds that have germinated will soon be followed by primary growth because of the shoot and root tip meristematic there are network (always splitting). Elongation of the root tip and the tip of the rod is called the primary growth. In dicotyledonous plants are cambium tissue which is a secondary meristem will cause secondary growth (enlarged). Cambium will cleave to the outward form of bark (phloem), and splitting the direction in shaping wood (xylem). In monocots no cambium so that only primary growth alone. Primary and secondary growth continues during the plant life. There are two kinds of growth, namely:
1. Primary Growth
Occur as a result of cell division-cell primary meristem tissue. Takes place in the embryo, part of the ends of the plants such as roots and stems.
The embryo has three important parts:
a. embryonic stem that is a candidate stems and leaves
b. embryonic roots are roots candidate
c. cotyledons ie food reserves

Plant growth can be measured with an instrument called auksanometer.
Regional growth in roots and stems divided based activities into 3 regions
a. Area division cells in this region actively dividing (meristematic)
b. Elongation area. Is behind the cleavage area.
c. Regional differentiation. Rearmost part of the growth area. Cells undergo differentiation to form the actual roots and young leaves and lateral buds will be a branch.

2. Secondary Growth
Is the activity of the cells of the secondary meristem cambium and cork cambium. This growth is found in dicotyledonous plants, gymnosperms and causes enlargement of the plant size (diameter). First cambium is only found in the vascular bundles, called cambium Vasis or cambium intravasikuler. Its function is to form the primary xylem and phloem. Next parenchyma root / stem that lies between the vascular bundles, be called the cambium intervasis cambium.
Cambium intravasis and intervasis circle year: concentric shape. Cambium which is located next to the skin tissue that serves as protector. Formed as a result of an imbalance between the xylem and phloem permbentukan faster than the growth of the skin.
Into forming feloderm: living cells
Outward form felem: dead cells

Factors affecting the growth and development. Growth in plants is influenced by two factors, namely:
a.
External factors
External factors are material or things that are outside of the plants that have an impact on the plants, either directly or indirectly. Belong to the external factors are light, temperature, water, mineral salts, climate, Earth's gravity, and others.
1.      Nutrition
Plants need a certain amount of mineral elements. Elements are required in large quantities called macro elements, while the elements required in small amounts called micronutrients.
2. Light
Light is absolutely needed by all green plants to perform photosynthesis, but its influence on the growth of plants is to inhibit germination, because light can lead to the disintegration of auxin that can inhibit growth. It can be proved if we put two sprouts, which is one in a dark place and the other in the light. In the same period, the sprouts in a dark place to grow faster but not normal. Very rapid growth in the dark is called etiolation.


In plants, there is a pigment called phytochrome, which serves to control the growth and development of chloroplasts, chlorophyll synthesis, formation of plant hormones (eg gibberellins), and setting the position of the leaves to sunlight. Additionally, phytochrome also affect photoperiodism, namely the influence of the length of the lighting effect on the growth and flower formation.
Based on the length and intensity of exposure, plants are grouped into three types, namely:
Plant for days shorter (shortday plant): Flowering and fruiting when the irradiation period is shorter than the critical period. For example: strawberry, dahlias, daisies, and krisatinum.
Plant for days long (longday plant): flowering and fruiting when the irradiation period is longer than the critical period. Examples: spinach lettuce, wheat, and potatoes.
Plant neutral (dayneutral plant): Not influenced by the length of the period of irradiation. Example: roses, anyer, and sunflower.
3.
Temperature
In general, the temperature will affect the action of the enzyme. When the temperature is too high, the enzyme will be broken, and if the temperature is too low enzyme becomes inactive.
4. The moisture or water content
Up to certain limits, the higher the water content, growth will accelerate. As more moisture is absorbed and evaporated fewer, will lead to the unfolding of the cells, so the cells more rapidly reaches its maximum size.
b. Internal factors
In addition to genetic factors, which include factors in are the hormones involved in plant growth. Hormones are substances produced by plants, usually in very small amounts in physiological functioning to control the direction and speed of growing parts of the plant.


B.     Curve of Plant Growth

During the life cycle, the plant will experience growth and development. Growth is the addition of weight and volume or size of the plant due to the addition of elements - a new structural element.
The pattern of growth of an organ or whole plant form sigmoid growth, is the slow growth in the initiation phase and then the next phase of growth will be faster exponentially. Further growth will be slowed and eventually will be approximately constant, so will makes growth curve that resembles the letter "S". This is consistent with the literature Tjitrosomo (1991) which states that plant growth was slow at first, then gradually fade faster until a maximum is reached, eventually the rate of growth decreases. If depicted in the graph in a given time will form a sigmoid curve (form S).
On plant growth slow at first, then gradually faster until a maximum is reached, eventually the rate of growth decreases. According to Franklin P Gardner (1991), is a sigmoid curve along a generation of growth pattern is typically characterized by a function of growth. Sigmoid curve shape for all the plants more or less fixed, but deviations may occur as a result of variations in the environment. The final size, appearance and shape of the plant is determined by the combined influence of heredity and environment (Tjitrosomo, 1999). In addition, the age of the leaves can also affect the growth of plants as they relate to the level of the rate of photosynthesis. The ability of leaves to photosynthesize increased in the early development of the leaves, but then began to fall, sometimes before the leaves are fully developed (fully developed). The leaves began having senencene is yellow and lost its ability to photosynthesize because reshuffle chlorophyll and loss of function of chloroplasts (Lakitan, 1995).

    
Fig. 15.2 GROWTH CURVE- GROWTH PLOTTED AGAINST TIME

Plants will experience growth and development as long as the phase of life. The development of plants is very diverse, as well as developments in the leaves that have a variety of shapes. Outward ongoing development through division, both periklinal and anticlinal, at the end of the primordial (aspect / distal end). Then when the leaves are about - about 1mm size, meristematic activity began to occur in all parts of prolonged. In dicotyledonous plants leaves, most of the cell division had long stopped before the leaves develop fully, often when the leaves reach less than half the size of the end. In the logarithmic phase, size (V) increases exponentially with time (t), which means slower growth rate initially running, but then continues to rise, the linear phase, increase the size of the constant breaks, usually at the maximum rate for some time. Constant growth rate is shown by a constant slope on the top of a high curve and the flat part of plant growth rate curve at the bottom, and the aging phase is characterized by a fixed rate of growth or even decline when growth reached a constant maturity (Dwidjoseputro. 1986) . Aging phase is characterized by the growth rate decreases when the plant has reached maturity and aging (Salisbury and Ross, 1992).

BIBLIOGRAPHY

       Devlin, Robert M. 1993. Plant Physiology. California : Wadsworth Publishing
      Company.
       Dwidjoseputro. 1986. Pengantar Fisiologi Tumbuhan. Jakarta : Gramedia.
       Lakitan, Benyamin. 1995. Dasar-Dasar Fisiologi Tumbuhan. Jakarta : Gramedia.
       Ritchie, Donald D. 1979. Biology . New York : Addison Wesley Publishing Company.
       Salisbury, F.B dan C.W. Ross., 1992. Fisiologi Tumbuhan Jilid Tiga Edisi Keempat.
      Bandung : ITB.
       Tjitrosomo, G. 1999. Botani umum 2. Bandung : Angkasa.


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