AGRI 31 Second Lecture Exam Flashcards
The attainment of size by virtue of growth and
architectural style by morphogenesis
Development
the irreversible increase of cell number, and
essentially its dry mass or weight
Growth
The reflection of change in the cell’s biochemical program,
controlled by developmental genes
Differentiation
Reflects the orderly processes by which genetically identical
cells become different, forming specialized tissues and
organs
Differentiation
the reversal of the cell specialization
Dedifferentiation
Important in the repair of injury, where cell near damaged
sites become totipotent and reprogram their development
Dedifferentiation
orientation and integration of differentiated cells in
space together with regulated growth 🡪 whole plant
Organization
the orientation and integration of differentiated cells in
space together with regulated growth, and the consequent
attainment of form and structure of the complete organism.
Morphogenesis
Essential characteristics of organisms
-take up relatively________from environment and
synthesize these to ___________
simple substance
complex substances
Growth is restricted to certain embryonic regions called the
_________
meristems
♣Where plant growth occurs
♣Site of repeated cell division of unspecialised cells
♣Cells differentiate, and become specialised in relation to the
function they will perform
Meristems
Cotyledons, shoots and root apical meristems
Embryo
- Shoot
- Axillary root (apical and lateral)
- Floral
- Cambiums (cork, vascular)
Meristems
♥tips of roots and shoot
♥site of primary growth in a plant
Apical
♥side portions, arising from the cambium (base of nodes and stems),
♥responsible for secondary thickening of the stem and roots
Lateral
♥inserted between regions of differentiated tissues
Intercalary
Types of Growth
- Indeterminate (ricebean , winged bean)
2. Determinate (corn, rice, mungbean)
-apical meristems of the roots and stems remain permanently embryonic over long periods
Indeterminate
-other plant parts (leaves, flowers, fruits) are embryonic for limited
period before the plant reaches maturity, have precise morphology and
definite number of parts
Determinate
The regulatory effects exerted by one part of the plant on the
growth or development in another part
Correlation Effect
♥As shoot increases in bulk, the size of the root system becomes
proportionately larger
♥Reduction in vegetative growth when the plant is fruiting
♥Stimulation of fruit growth by hormones produced in the
developing seeds
♥Stimulating effects of buds/leaves on the rooting of stem cuttings
Organ Differentiation
•
Many aspects of plant behavior exhibit periodic oscillations that
appear to be controlled by an internal time measuring system:_____________________
the endogenous biological clock
The Biological Clock Manifestations
♥Diurnal rise and fall of leaves (sleep movements)
♥Photosynthesis is diurnal
Classifications of Biological Rhythms
- Circadian Rhythm
- Lunar rhythm
- Annual rhythm
- Ultradian rhythm
=day) = 24 hours eg bean
movement ( hyponasty, epinasty ) (example: Portulaca , Calathea, rain
tree or Fertility Tree of UPLB)
Circadian Rhythm ( about+diem =day) = 24 hours
= 28 days, between one full moon to the next
Lunar rhythm
––(flowering of fire trees, cherry blossoms
and kapok every summer)
Annual rhythm
= <24
hrs
Ultradian rhythm
result of differential growth within an organ or between 2 different
organs ( irreversible)
Growth movements
Plant Movements
- Growth movements
* Turgor movements
•
Results from volume changes in certain cells due to changes in
osmotic potential (water) pressure due to the influx or efflux of
ions which in turn cause water to move in and out of the cells
reversible, but not all the time)
Turgor movements
Result from differential growth of specific organs of a plant
Tropisms
- the plant moves toward the stimulus
ex. bending toward light
♣Positive tropisms
movements away from the stimulus
♣Negative tropisms
movement in response to
light
Phototropism
Growth movements in response to gravity
Gravitropism
•negatively gravitropic, away from the center (
•plant shoots exhibit negative gravitropism because they
grow away from gravity
Shoots
•positively gravitropic, towards the earth’s center(+)
Roots
-directional response of a plant organ to touch or physical contact
with a solid object
-curling of threadlike
appendages in vines
Thigmotropism
- changing position and facing normal to the sun throughout the day
- the solar tracking of plant organs example: sunflowers
Heliotropism
Under Photoperiodism
- Long day plants
- Short day plants
- Day neutral plants
-Flower when daylength is longer than a critical value
-Long day plants
-Flower when the daylength is shorter than a critical value
-Short day plants
-Flower when they become mature regardless of daylength
-Day neutral plants
-malunggay , aster, gladiola, fire tree, golden shower
-Long day plants
beans, poinsettia
-Short day plants
a slowdown in an organisms metabolic rate
Dormancy
-inability of viable seed s to germinate
given favorable conditions for germination.
•
Normally, a flower which is pollinated develops into a fruit,
containing seeds derived from the fertilized egg cell
Seed dormancy
fruit development without fertilization
Parthenocarpy
-the collective term for aging processes that lead to the death
of a plant or plant part
SENESCENCE
• -Organic substances other than nutrients •Effective at low concentrations •Naturally occuring •Modify plant growth and development (quantitative/qualitative) More than one hormone is involved in the control of physiological processes but only one tends to dominate the control process
Phytohormones
–organic substances effective at low concentrations that modify
plant growth and development
–produced naturally by plants
Hormones
–may be synthetic compounds (e.g., IBA and Cycocel ) that mimic
naturally occurring plant hormones, or
–may be natural hormones that were extracted from plant
tissue (e.g., IAA)
Plant Growth Regulators
•
synthesized in shoot apical meristems, young leaves, seeds
and fruits
•
promote growth in molar concentrations of 10^-3 to 10^-8
Auxins
- Auxin produced chemically
- synthesized from indole or tryptophan
Indoleacetic Acid (IAA)
•
Promote lateral and adventitious root development
Auxins
fruit development in the absence of fertilization
parthenocarpy (fruit development in the absence of fertilization)
♣toxic in large concentrations
♣affect mostly dicots but not monocots
♣Monocots seem to be able to rapidly degrade the
synthetic auxins
Auxins
•phenyl urea derivatives of adenine, one of the molecules in
DNA
♣found in actively dividing tissues of seeds, fruits, leaves and
root tips, and wound tissue sites
♣transported through xylem to the rest of the plant
Cytokinin
are produced in roots and younger leaves,
with seeds having the highest concentration
Gibberellins
♥Reversal of genetic dwarfism GA
♥Bolting of biennials, to produce flowers during the first
growing season
Effects of Gibberellins
on Elongation
•commercial applications
in grape industry, where
grapes grow larger, and
with longer internodes
Gibberellins
♥inhibits growth activities in times of environmental stress
rather than by promoting growth
♥often serves as an antagonist to the other growth
promoting hormones in plants.
Abscisic Acid
ABA is also referred to as the _______________
stress activity hormone
♥Promotes flowering
♥promotes leaf senescense
Ethylene
- Climatic (climate, weather)
- Edaphic/Soil factors
- Climatic stresses (drought, salinity, acidity, lahar, La Niña
- El Niño, greenhouse effect ,global warming
Abiotic
•Beneficial organisms (pollinators, decomposers, natural
enemies)
•Pests (arthropods, pathogens, weeds, vertebrate pests
•Allelopathy
Biotic
the atmospheric conditions in any area at
any time, with regards to sun, cloud, temperature,
wind and rain, etc.(deviation from pattern)
Weather
the long term weather pattern of an
area, including temperature, precipitation, and
wind or weather averaged over long period of
time (seasonal pattern)
Climate
Rate at which a surface absorbs radiation (Watt/m2)
- Solar Radiation
Direct effect on Photosynthesis
1.Photoenergetic effect
effect on development of plants
2.Photocybernetic effect
red and blue
Photosynthesis
far red and red
Photoperiodism
-Amount of solar radiation that reaches the outer limits of the earth’s atmosphere -Solar constant = 2.0 cal /cm 2 /min (15% fluctuation within the year)
Solar constant
used by plants to fix CO2 during Photosynthesis
PAR-photosynthetically active radiation (PAR)
Classification based on light intensity requirements
- Heliophytes
- Sciophytes
sun loving
Heliophytes
shade loving
-Sciophytes
reflected radiation/total incident light.
Reflects how fast and what degree surface is
heated
Albedo
varies with latitude, different between day and night and
increases as latitude from equator increases
Flowering and germination are affected by __________
daylength
Plant response as conditioned by daylength
Photoperiodism
germination response with respect to daylength
Photoblastism
Plants that grow in Cool season
cole crops
Plants that grow in warm season
rice, banana
Plants that grow in tropical
coconut
Plants that grow in Sub-tropical
citrus
= measurement of departure of the
daily mean temperature above the minimum
threshold temperature for the plant (base temp)
Degree day
-Water in some form (Rain , drizzle, fog, mist,
snow, hail) falling out of the air, and settling
on the surface of the earth
-Precipitation is a condensation in the atmosphere.
Precipitation/Rainfall
is condensation at the surface and thus is not a
form of precipitation
Dew
Roles of water in plant growth
•Reactant in many biological processes
•Medium of transport of nutrients and
other substances
•Temperature regulation
Classification based on need for moisture
Xerophytes
Hydrophytes
Mesophytes
desert plants
Xerophytes
aquatic plants
Hydrophytes
land plants
Mesophytes
affects seasonal distribution of precipitation
Air circulation
affects amount and distribution of rainfall
Topography
influences the phytogeographic distribution of plants
Moisture
Rain formation requires:
- High RH
- Sufficient low temperature
- Condensation nuclei
- Sufficiently low pressure
The electromagnetic radiation with wavelengths longer
than visible light and shorter than microwaves. It is felt
as heat.
Infrared Radiation
The most important greenhouse gases are:
- CO 2 Carbon Dioxide
- CH 4 methane
- N 2 O nitrous oxide
- Chloroflourocarbons (CFC)
Levels of greenhouse gases have increased by about ______ since large scale industrialization began around
150 years ago
25 percent
•Rising concentrations of greenhouse gases produce an increase in the
average surface temperature of the Earth over time
•Rising temperatures may, in turn, produce changes in precipitation
patterns, storm severity, and sea level commonly referred to as
Climate Change
The movement (“flux”) of carbon between the atmosphere and the land and oceans dominated by natural processes, eg PS.
Carbon Cycle
positive imbalance between greenhouse gas
emissions and absorption resulting in the continuing
increase in atmospheric concentrations of greenhouse gases
Net effect
what are the Air Pollutants
- Carbon monoxide and carbon dioxide
- Particles dust, soot, heavy metals
- Sulfur dioxide
- Flourides
- Phytochemical smog O 3 , PAN, N2O
Ozone occurs naturally in the Earth’s upper
atmosphere 6 to 30 miles above the Earth’s surface where it
forms a protective layer that shields us from the sun’s harmful
ultraviolet rays
Good Ozone.
In the Earth’s lower atmosphere, near ground
level, ozone is formed when pollutants emitted by cars, power
plants, industrial boilers, refineries, chemical plants, and other
sources react chemically in the presence of sunlight
Bad Ozone.
- Based on precipitation and temperature
* PHL is classified as tropical and rainy
•Koppen’s classification
•Based on the difference between the mean
Thornthwaite’s classification
- based on precipitation
* PHL has four basic types of climate
Modified Corona classification
Climate Classifications
Koppen’s classification
Thornthwaite’s classification
Modified Corona classification
- Two pronounced seasons
* Dry from Nov to Apr (less than 50mm rain/ mo
Type 1
- No dry season
- Very pronounced maximum rains during Nov to Jan
- No single dry month in regions of this type
Type 2
- Intermediate of Types 1&2, resembles more of type 1
- Seasons not very pronounced
- Dry season: 1 3 months
Type 3
- Intermediate of Types 1&2, resembles more of type 2
* Rainfall more or less evenly distributed
Type 4
totality of the genetic make-up of an organism; affected by environment to produce the phenotype
Genotype
- group of plants within a particular cultivated species
- distinguished by a character or group of characters
Variety
- a distinct variant selected by someone who believed it was uniquely different from any plant already in cultivation
Cultivar (cultivated variety)
-cultivars that are propagated by vegetative means
Clones
propagated by seeds
Lines
- plants of actual or potential value for the present and the future generations;
- raw materials for plant breeding;
- component of biodiversity.
Plant genetic resources
variability in all living things, life on earth
Biodiversity
-wild species, weedy races, traditional varieties, obsolete varieties, products of plant breeding, GMOs
Genetic resources of crops
SOIL
PROPERTIES
- Physical
- Chemical
- Biological
size and relative proportions of
various size groups in a given soil
Texture
arrangement of soil particles into
groups or aggregates
Structure
top and sub soil
Soil Depth
physical configuration of the soil
surface (drainage, run off, erosion)
Topography
-refers to the grouping of particles of sand, silt,
and clay into larger aggregates of various sizes
and shapes
Soil Structure
Movement of air, water, and plant roots through a soil
is affected by
Soil Structure
Result in a network of soil pores that allow rapid
exchange of air and water with plant roots.
Plant growth depends on rapid rates of exchange.
Stable Aggregates
How to maintain Good Soil Structure:
- crop rotation
- organic matter addition
- timely tillage practices
-difficult to maintain aggregate stability due to
low organic matter, clay content and resistance
of sand particles to cementing processes
Sandy Soils
Refers to the thickness of soil materials which provide
structural support, nutrients, and water for plants
Soil Depth
is a measure of the ability of air
and water to move through it
Soil’s permeability
-“lay of the land” or physical configuration of soil
surface
-impact on whether a field can be irrigated
Topography
component of topography that refers to the
difference in height between the hills and depressions
in the field
-affects the type of irrigation system to be used,
the water conveyance system (ditches or pipes),
drainage requirements and water erosion control
practices
Relief
A measure of the acidity or alkalinity of a
soil
Soil pH
= 7.0
Neutral
< 7.0
Acidic
> 7.0
Alkaline
is a measure of the quantity of cations that can be adsorbed and held by a soil
- is dependent upon the amount of organic
matter and clay in soils and on the types of clay
Cation Exchange Capacity (CEC)
Mice, moles, etc.; Earthworms and other worms; Ants,
beetles, termites, spiders
Macrofauna
: Nematodes, arthropods (mites, centipedes, and springtails),
mollusks
Mesofauna
: Protozoa
Microfauna
- Most numerous in soil
- Most diverse metabolism
- Can be aerobic or anaerobic
- Optimal growth at pH 6 8
Bacteria
Allelopathy
allelon–_________________
pathos–means “____”
“of each other”
to suffer
refers to the chemical inhibition of one species by another.
The “inhibitory” chemical is released into the environment where it affects
the development and growth of neighboring plants
Allelopathy
insufficiency of rainfall/moisture
Drought
29 consecutive days without
rainfall of at least 0.25 mm
Absolute drought
15 consecutive days without
rainfall of at least 0.25mm
Partial drought
Methods of Conservation
ex situ
in situ
conservation outside the natural habitat
ex. seed & field genebanks
ex situ
conservation in the natural habitat
in situ
Sources of variation
▪Mutation
▪Migration
▪Recombination
selecting the best looking plants/seeds and
saving them
to plant for the next year’s crop
▪
Selection
modifying the genetic composition of plants by making
crosses and selecting new superior genotype
combinations
Traditional plant breeding
-
a new type of genetic modification, involving the purposeful
addition of a foreign gene or genes to the genome of an
organism.
Genetic engineering
use of living organisms or their parts to
make or modify products, or improve plants,
animals and microorganisms
Biotechnology
…allows direct introduction of genes from
one species to another through DNA
manipulation (recombinant DNA)
Modern biotechnology
… refers to specific gene transfer from the
same or related or unrelated species
resulting in gene expression and production
of new trait(s) in an organism
Genetic Engineering
the warming of water in
the Pacific Ocean
El Nino
the cooling of water in
the Pacific Ocean
La Nina
