plant growth Flashcards
as an irreversible permanent increase in size of an organ or its parts or even of an individual cell.
growth
accompanied by metabolic processes
growth
is indeterminate due to the presence of meristem (Open form of growth)
plant growth
is measured by a variety of parameters some of which are: increase in fresh weight, dry weight, length, area, volume and cell number
growth
phases of growth
• Meristematic
• Elongation
• Maturation
• The increased growth per unit time is termed as
growth rate
• An organism, or a part of the organism can produce more cells in a variety of ways.
A. Arithmetic B. Geometric
is a term that includes all changes that an organism goes through during its life cycle from germination of the seed to senescence
development
Plants follow different pathways in response to environment or phases of life to form different kinds of structures.
plasticity
are small, simple molecules of diverse chemical composition
plant growth regulator
auxins, gibberellins and cytokinins
plant growth promoters
regulator - abscisic acid
Plant growth inhibitors
can easily isolated/extracted from plants
free auxin
organic solvents are needed during extraction
bound auxin
inhibits/stops auxin activities
anti auxin
lengthen plant cells in the growing tip.
– stimulates growth of primary stem – controls some forms of tropism
auxin
is the movement of plant in response to an environmental stimulus.
tropism
• Stimulates cell elongation
• Stimulate differentiation of xylem and phloem • Suppresses growth of lateral buds
• Delay leaf senescence
• Promotes abscission in old leaf and mature/ripened fruits
Auxin
plant hormones that produce dramatic increases in size.
gibberellins
• ending seed dormancy
• rapid growth of young seedlings
• rapid growth of some flower stalks
gibberellins
was one of the first gibberellins to be discovered and remains the most intensively studied form.
gibberellic acid GA3
• Their ability to cause an increase in length of axis is used to increase the length of grapes stalks.
• cause fruits like apple to elongate and improve its shape.
gibberellins
used to speed up the malting process in brewing industry
GA3
promotes bolting (internode elongation just prior to flowering) in beet, cabbages as a result of several factors, including changes in day length, the prevalence of high temperatures at particular stages in a plant’s growth cycle, and the existence of stresses such as insufficient water or minerals.
gibberellins
stimulate cytokinesis.
• final stage in cell division
• produced in growing roots, seeds, and fruits
• involved in growth of side branches
cytokinins
are most abundant in growing tissues, such as roots, embryos, and fruits, where cell division is occurring.
cytokinins
are known to delay senescence in leaf tissues,
• promote mitosis
• stimulate differentiation of the meristem in shoots and roots.
cytokinins
causes the ripening of fruits.
ethylene
promotes senescence and abscission of plant organs especially of leaves and flowers
ethylene
breaks seed and bud dormancy
It helps leaves/ upper parts of the shoot to remain above water.
ethylene
also promotes root growth and root hair formation, thus helping the plants to increase their absorption surface.
ethylene
accumulates as a response to stressful environmental conditions, such as dehydration, cold temperatures, or shortened day lengths
ABA
inhibits stem elongation and induces dormancy in lateral buds.
ABA
specially to the promotion of flowering by a period of low temperature
vernalization
constantly dividing cells, rich in protoplasm,conscicuous nuclei
merismatic
increased vacuolation, cell enlargement, new cell wall deposition
elongation
attain the maximal size in terms of wall thickening
maturation
root apical and shoot apical meristem and cambium differentiate and mature
cells undergo few to major structural changes
differentiation
the living differentiated cells
lost the capacity to divide
can regain
dedifferentiation
differentiated cells return to their original specialized form
redifferentiation
