This document discusses conventional plant breeding techniques used over thousands of years by farmers and more recently by plant breeders to develop improved crop varieties. It describes how early farmers selected desirable traits from local varieties to save and replant, while modern plant breeders use genetics knowledge to cross plants with desired traits. The result is either open-pollinated varieties that breed true, or hybrid varieties produced by crossing pure parent lines to yield high-performing first generation offspring, though hybrid seeds must be repurchased annually. Conventional breeding has significantly increased global food production but has limitations; new techniques like mutation breeding and biotechnology further expand options.
All living organisms have the ability
to improve themselves through
natural means in order to adapt to
changing environmental conditions.
However, it takes hundreds of years
before any detectable improvement
is obtained. Man then learned how
to domesticate and breed plants
in order to develop crops to his
own liking and needs using various
means including biotechnology.
Biotechnology is defined as
a set of tools that uses living
organisms (or parts of organisms)
to make or modify a product,
improve plants, trees or animals,
or develop microorganisms
for specific uses. Agricultural
biotechnology is the term used in
crop and livestock improvement
through biotechnology tools. This
monograph will focus only on
agricultural crop biotechnology.
Biotechnology encompasses a
number of tools and elements of
conventional breeding techniques,
bioinformatics, microbiology,
molecular genetics, biochemistry,
plant physiology, and molecular
biology.
The biotechnology tools that
are important for agricultural
biotechnology include:
- Conventional plant breeding
- Tissue culture and
micropropagation
- Molecular breeding or marker
assisted selection
- Genetic engineering and GM
crops
- Molecular Diagnostic Tools
You too Can Be a Seed Saver: A Guide to Seed Saving
`
For more information, Please see websites below:
`
Organic Edible Schoolyards & Gardening with Children =
http://scribd.com/doc/239851214 ~
`
Double Food Production from your School Garden with Organic Tech =
http://scribd.com/doc/239851079 ~
`
Free School Gardening Art Posters =
http://scribd.com/doc/239851159 ~
`
Increase Food Production with Companion Planting in your School Garden =
http://scribd.com/doc/239851159 ~
`
Healthy Foods Dramatically Improves Student Academic Success =
http://scribd.com/doc/239851348 ~
`
City Chickens for your Organic School Garden =
http://scribd.com/doc/239850440 ~
`
Simple Square Foot Gardening for Schools - Teacher Guide =
http://scribd.com/doc/239851110 ~
A Guide to Seed Saving: You too Can be a Seed Saver
`
For more information, Please see websites below:
`
Organic Edible Schoolyards & Gardening with Children =
http://scribd.com/doc/239851214 ~
`
Double Food Production from your School Garden with Organic Tech =
http://scribd.com/doc/239851079 ~
`
Free School Gardening Art Posters =
http://scribd.com/doc/239851159 ~
`
Increase Food Production with Companion Planting in your School Garden =
http://scribd.com/doc/239851159 ~
`
Healthy Foods Dramatically Improves Student Academic Success =
http://scribd.com/doc/239851348 ~
`
City Chickens for your Organic School Garden =
http://scribd.com/doc/239850440 ~
`
Simple Square Foot Gardening for Schools - Teacher Guide =
http://scribd.com/doc/239851110 ~
Seed Production and Seed Sources of Organic Vegetables
`
For more information, Please see websites below:
`
Organic Edible Schoolyards & Gardening with Children =
http://scribd.com/doc/239851214 ~
`
Double Food Production from your School Garden with Organic Tech =
http://scribd.com/doc/239851079 ~
`
Free School Gardening Art Posters =
http://scribd.com/doc/239851159 ~
`
Increase Food Production with Companion Planting in your School Garden =
http://scribd.com/doc/239851159 ~
`
Healthy Foods Dramatically Improves Student Academic Success =
http://scribd.com/doc/239851348 ~
`
City Chickens for your Organic School Garden =
http://scribd.com/doc/239850440 ~
`
Simple Square Foot Gardening for Schools - Teacher Guide =
http://scribd.com/doc/239851110 ~
All living organisms have the ability
to improve themselves through
natural means in order to adapt to
changing environmental conditions.
However, it takes hundreds of years
before any detectable improvement
is obtained. Man then learned how
to domesticate and breed plants
in order to develop crops to his
own liking and needs using various
means including biotechnology.
Biotechnology is defined as
a set of tools that uses living
organisms (or parts of organisms)
to make or modify a product,
improve plants, trees or animals,
or develop microorganisms
for specific uses. Agricultural
biotechnology is the term used in
crop and livestock improvement
through biotechnology tools. This
monograph will focus only on
agricultural crop biotechnology.
Biotechnology encompasses a
number of tools and elements of
conventional breeding techniques,
bioinformatics, microbiology,
molecular genetics, biochemistry,
plant physiology, and molecular
biology.
The biotechnology tools that
are important for agricultural
biotechnology include:
- Conventional plant breeding
- Tissue culture and
micropropagation
- Molecular breeding or marker
assisted selection
- Genetic engineering and GM
crops
- Molecular Diagnostic Tools
You too Can Be a Seed Saver: A Guide to Seed Saving
`
For more information, Please see websites below:
`
Organic Edible Schoolyards & Gardening with Children =
http://scribd.com/doc/239851214 ~
`
Double Food Production from your School Garden with Organic Tech =
http://scribd.com/doc/239851079 ~
`
Free School Gardening Art Posters =
http://scribd.com/doc/239851159 ~
`
Increase Food Production with Companion Planting in your School Garden =
http://scribd.com/doc/239851159 ~
`
Healthy Foods Dramatically Improves Student Academic Success =
http://scribd.com/doc/239851348 ~
`
City Chickens for your Organic School Garden =
http://scribd.com/doc/239850440 ~
`
Simple Square Foot Gardening for Schools - Teacher Guide =
http://scribd.com/doc/239851110 ~
A Guide to Seed Saving: You too Can be a Seed Saver
`
For more information, Please see websites below:
`
Organic Edible Schoolyards & Gardening with Children =
http://scribd.com/doc/239851214 ~
`
Double Food Production from your School Garden with Organic Tech =
http://scribd.com/doc/239851079 ~
`
Free School Gardening Art Posters =
http://scribd.com/doc/239851159 ~
`
Increase Food Production with Companion Planting in your School Garden =
http://scribd.com/doc/239851159 ~
`
Healthy Foods Dramatically Improves Student Academic Success =
http://scribd.com/doc/239851348 ~
`
City Chickens for your Organic School Garden =
http://scribd.com/doc/239850440 ~
`
Simple Square Foot Gardening for Schools - Teacher Guide =
http://scribd.com/doc/239851110 ~
Seed Production and Seed Sources of Organic Vegetables
`
For more information, Please see websites below:
`
Organic Edible Schoolyards & Gardening with Children =
http://scribd.com/doc/239851214 ~
`
Double Food Production from your School Garden with Organic Tech =
http://scribd.com/doc/239851079 ~
`
Free School Gardening Art Posters =
http://scribd.com/doc/239851159 ~
`
Increase Food Production with Companion Planting in your School Garden =
http://scribd.com/doc/239851159 ~
`
Healthy Foods Dramatically Improves Student Academic Success =
http://scribd.com/doc/239851348 ~
`
City Chickens for your Organic School Garden =
http://scribd.com/doc/239850440 ~
`
Simple Square Foot Gardening for Schools - Teacher Guide =
http://scribd.com/doc/239851110 ~
Four new resources from Organic Seed Alliance (OSA), developed and produced with funding from OFRF and Clif Bar Family Foundation’s Seed Matters initiative, provide a wealth of information for farmers who want to learn the art and craft of plant breeding. The comprehensive manuals walk farmers through the methods of breeding new crop varieties on the farm. - See more at: http://ofrf.org/blogs/new-tools-organic-farmers-teach-diy-plant-breeding#sthash.clHAu7FF.Fd4spHEW.dpuf
ICRISAT’s Seed Systems Models and Lessons Learned booklet explains the rationale of ICRISAT’s work on seed systems in the drylands, the different approaches and their impact on the ground. Improving farmers’ access to improved seeds in the drylands is seen as a cost-effective strategy to improve farm productivity and food security. Different models of seed systems are tested and developed by ICRISAT and its development partners in sub-Saharan Africa and Asia depending on the local context. It includes small seed packets, groundnut seed revolving fund in Malawi, support to community-based systems, farmer seed organizations or local seed ventures, and public private seed partnerships like the Hybrid Parents Research Consortium for pearl millet and sorghum in India. ICRISAT’s vision on seed systems is demand-driven, holistic and working in partnership, along the crop value chain.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
Four new resources from Organic Seed Alliance (OSA), developed and produced with funding from OFRF and Clif Bar Family Foundation’s Seed Matters initiative, provide a wealth of information for farmers who want to learn the art and craft of plant breeding. The comprehensive manuals walk farmers through the methods of breeding new crop varieties on the farm. - See more at: http://ofrf.org/blogs/new-tools-organic-farmers-teach-diy-plant-breeding#sthash.clHAu7FF.Fd4spHEW.dpuf
ICRISAT’s Seed Systems Models and Lessons Learned booklet explains the rationale of ICRISAT’s work on seed systems in the drylands, the different approaches and their impact on the ground. Improving farmers’ access to improved seeds in the drylands is seen as a cost-effective strategy to improve farm productivity and food security. Different models of seed systems are tested and developed by ICRISAT and its development partners in sub-Saharan Africa and Asia depending on the local context. It includes small seed packets, groundnut seed revolving fund in Malawi, support to community-based systems, farmer seed organizations or local seed ventures, and public private seed partnerships like the Hybrid Parents Research Consortium for pearl millet and sorghum in India. ICRISAT’s vision on seed systems is demand-driven, holistic and working in partnership, along the crop value chain.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
1. Pocket Ks
Pocket Ks
Pocket Ks
Pocket Ks
Pocket Ks are Pockets of Knowledge,
packaged information on crop
biotechnology products and related
issues available at your fingertips. They
are produced by the Global Knowledge
Center on Crop Biotechnology (http://
www.isaaa.org/kc). For more
information, please contact the
International Service for the Acquisition
of Agri-biotech Applications (ISAAA)
SEAsiaCenter c/o IRRI, DAPO Box
7777, Metro Manila, Philippines.
Tel: +63-2 8450563
Fax: +63-2 8450606
E-mail: knowledge.center@isaaa.org
INTERNATIONAL SERVICE
FOR THE ACQUISITION
OF AGRI-BIOTECH
APPLICATIONS
Global Knowledge Center
on Crop Biotechnology
First Printing, March 2004
Conventional Plant
Breeding
References
Bauman, F. and Crane, P.L. 1992. Hybrid corn
- History, development and selection
considerations. National Corn Handbook.
Purdue University, US.
DANIDA. 2002. Assessment of potentials and
constraints for development and use of
plant biotechnology in relation to plant
breeding and crop production in developing
countries. Working paper. Ministry of
Foreign Affairs, Denmark.
East-West Seeds 1982-2002. 2002.
Vegetable Breeding for Market
Development. Edited by Karl Kunz.
Bangkok, Thailand.
Food and Agriculture Organization. 2002.
Crop Biotechnology: A working paper for
administrators and policy makers in Sub-
Saharan Africa.
History of Plant Breeding (http://
www.colostate.edu/programs/lifesciences/
TransgenicCrops/history.html)
Hybrid varieties and saving seed
(http://aggie-horticulture.tamu.edu/
plantanswers/vegetables/seed.html)
International Rice Research Institute. (http://
www.irri.org)
Conclusion
Conventional plant breeding
resulting in open pollinated
varieties (OP) or hybrid varieties
has had a tremendous impact
on agricultural productivity over
the last decades. While an
extremely important tool,
conventional plant breeding also
has its limitations. First,
breeding can only be done
between two plants that can
sexually mate with each other.
This limits the new traits that can
be added to those that already
exist in a particular species.
Second, when plants are
crossed, many traits are
transferred along with the trait/s
of interest - including those traits
that have undesirable effects on
yield potential.
S
ince
the
practice
of
agriculture
began,
eight
to
ten
thousand
years
ago,
farmers
have
been
altering
the
genetic
makeup
of
the
crops
they
grow.
Early
farmers
selected
the
best
looking
plants
and
seeds
and
saved
them
to
plant
for
the
next
season.
Then,
once
the
science
of
genetics
became
better
understood,
plant
breeders
used
what
they
knew
about
the
genes
of
a
plant
to
select
for
specific
desirable
traits
to
develop
improved
varieties.
The
selection
for
features
such
as
faster
growth,
higher
yields,
pest
and
disease
resistance,
larger
seeds,
or
sweeter
fruits
has
dramatically
changed
domesticated
plant
species
compared
to
their
wild
relatives.
For
example,
when
corn
was
first
grown
in
North
and
South
America,
thousands
of
years
ago,
the
corn
cobs
farmers
harvested
were
smaller
than
one’s
little
finger.
Today,
there
are
hundreds
of
varieties
of
corn,
some
of
which
produce
cobs
as
long
as
one’s
forearm.
Conventional
plant
breeding
has
been
going
on
for
hundreds
of
years,
and
is
still
commonly
used
today.
Early
farmers
discovered
that
some
crop
plants
could
be
artificially
mated
or
cross-pollinated
to
increase
yields.
Desirable
characteristics
from
different
parent
plants
could
also
be
combined
in
the
offspring.
When
the
science
of
plant
breeding
was
further
developed
in
the
20th
century,
plant
breeders
understood
better
how
to
select
superior
plants
and
breed
them
to
create
new
and
improved
varieties
of
different
crops.
This
has
dramatically
increased
the
productivity
and
quality
of
the
plants
we
grow
for
food,
feed
and
fiber.
The
art
of
recognizing
desirable
traits
and
incorporating
them
into
future
generations
is
very
important
in
plant
breeding.
Breeders
scrutinize
their
fields
and
travel
long
distances
in
search
of
individual
plants
that
exhibit
desirable
traits.
A
few
of
these
traits
occasionally
arise
spontaneously
through
a
process
called
mutation,
but
the
natural
rate
of
mutation
is
very
slow
and
unreliable
to
produce
all
the
plant
traits
that
breeders
would
like
to
see.
(See
box
“Mutation
Breeding”.)
K
K
K
K
K
Pocket
No. 13
2. The end result of plant breeding is either an
open-pollinated (OP) variety or an F1 (first
filial generation) hybrid variety. OP varieties,
when maintained and produced properly,
retain the same characteristics when
multiplied. The only technique used with OP
varieties is the selection of the seed-
bearing plants.
Hybrid seeds are an
improvement over
open pollinated seeds
in terms of qualities
such as yield,
resistance to pests
and diseases, and
time to maturity. Hybrid
seeds are developed
by the hybridization or
crossing of parent lines that are ‘pure lines’
produced through inbreeding. Pure lines are
plants that “breed true” or produce sexual
offspring that closely resemble their
parents. By crossing pure lines, a uniform
population of F1 hybrid seed can be
produced with predictable characteristics.
The simplest way to explain how to develop
an F1 hybrid is to take an example. Let us
say a plant breeder observes a particularly
good habit in a plant, but with poor flower
color, and in another plant of the same type
he sees good color but poor habit. The best
plant of each type is then taken and self-
pollinated (in isolation) each year and, each
year, the seed is re-sown. Eventually,
every time the seed is sown the same
identical plants will appear. When they do,
this is known as a ‘pure line.’
If the breeder now
takes the pure line
of each of the two
plants he originally
selected and cross
pollinates the two by
hand the result is
known as an “F1
hybrid.” Plants are
grown from the
seed produced, and
the result of this cross pollination should
have the combined traits of the two
parents.
This is the simplest form of hybridization,
but there are complications, of course. A
completely pure line can sometimes take
seven or eight years to achieve.
Sometimes, a pure line is made up of
several previous crossings to build in
desirable features. The resulting plant is
then grown on until it is genetically pure
before use in hybridization.
In addition to
qualities like
good vigor,
trueness to
type, heavy
yields and high
uniformity
which hybrid plants enjoy, other
characteristics such as earliness, disease
and insect resistance and good water
holding ability have been incorporated into
most F1 hybrids.
Unfortunately, these advantages come with
a price. Because creating F1 hybrids
involves many years of preparation to
create pure lines that have to be constantly
maintained so that F1 seeds can be
harvested each year, the seeds then
become more expensive. The problem is
compounded because to ensure that no
self-pollination takes place, all the
hybridization of the two pure lines,
sometimes, has to be done by hand.
Another disadvantage is if the seeds of the
F1 hybrids are used for growing the next
crops, the resulting plants do not perform
as well as the F1 material - resulting in
inferior yields and vigor. As a consequence,
the farmer has to purchase new F1 seeds
from the plant breeder each year. The
farmer is, however, compensated by higher
yields and better quality of the crop.
Though more
expensive, hybrid
seeds have had a
tremendous impact
on agricultural
productivity. Today,
nearly all corn and
50% of all rice are
hybrids (DANIDA).
Hybrid seed technology
In the US, the
widespread use
of corn hybrids,
coupled with
improved cultural
practices by
farmers, has more
than tripled corn
grain yields over
the past 50 years
from an average
of 35 bushels per
acre in the 1930s
to 115 bushels per acre in the 1990s. No
other major crop anywhere in the world
even comes close to equaling that sort of
success story.
Hybrid rice technology helped China
increase its rice production from 140 million
tons in 1978 to 188 million tons in 1990.
Research at the International Rice Research
Institute (IRRI) and in other countries
indicates that hybrid rice technology offers
opportunities for increasing rice varietal
yields by 15-20%. And this is achievable
with the improved, semi-dwarf, and inbred
varieties (IRRI).
Many cultivars of popular vegetables or
ornamental plants are F1 hybrids. In terms
In the late 1920s, researchers
discovered that they could greatly
increase the number of these variations
or mutations by exposing plants to X-
rays and chemicals. “Mutation
breeding” was further developed after
World War II, when the techniques of the
nuclear age became widely available.
Plants were exposed to gamma rays,
protons, neutrons, alpha particles, and
beta particles to see if these would
induce useful mutations. Chemicals, too,
such as sodium azide and ethyl
methanesulphonate, were used to cause
mutations.
Mutation breeding efforts continue
around the world today. Of the 2,252
Mutation breeding
officially released mutation breeding
varieties, 1,019 or almost half have been
released during the last 15 years.
Examples of plants that have been
produced via mutation breeding include
wheat, barley, rice, potatoes, soybeans,
and onions. (For FAOs’ Mutant Variety
Database, visit http://www-mvd.iaea.org/
MVD/default.htm.)
of improved
plant
characteristics,
tropical
vegetable
breeders can
point to some
rather clear achievements over the last two
decades:
• Yield improvement. Hybrids often
outyield traditional OP selections by
50-100% due to its improved vigor,
improved genetic disease resistance,
improved fruit setting under stress,
and higher female/male flower ratios.
• Extended growing season. Hybrids
often mature up to 15 days earlier than
local OP varieties. For many crops, the
hybrid’s relative advantage over the
OP is most pronounced under stress
conditions.
• Quality improvement. Hybrids have
helped stabilize product quality at a
higher, and more uniform level – this
implies improved consumption quality
(e.g. firm flesh of wax gourd, crispy
taste of watermelon).