von Anshita Jaiswal Vor 4 Jahren
293
Mehr dazu
high milk yielding females and high quality meat yielding bulls obtained
PROCEDURE:
genetic mother are induced for another round of superovulation
the fertilised cells at 8-32 cells stage are recovered non-surgically and transferred to surrogate mothers
as the eggs are ready,the female is inseminated
a number of follicles undergo maturation producing 6-8 eggs
induces follicular maturation and superovulation
in this technique a female is administered with FSH
employed for herd improvement to improve chances of successful production of hybrids
:ADVANTAGES
contagious diseases don't spread
economical as semen of a single male is sufficient to inseminate a large number of females
the semen can be frozen and used later
high yielding males not available everywhere,semen can be collected and transported to distant places
ensures good quality progeny
the semen of the chosen male is collected and injected into the reproductive tract of the slected female by the breeder.
OUTBREEDING
Interspecific Hybridization
only performed when sterile hybrid is superior to either of the parents
different related species
Cross breeding
Allows the desirable qualities of two differenet breeds to be combined
different breeds
Out-crossing
single out-cross helps overcoming inbreedong depression
best for animals that are below average in milk production
same breed but no common ancestors up to 4-6 generations
It is the mating between unrelated animals belonging to the same breed or different breeds of the same species or between individuals of different species
INBREEDING
It is the mating of closely related individuals of the same species but from different populations
DISADVANTAGES
NOTE: to overcome inbreeding depression it is advisable to breed superior animals of the local populations with the superior animals of another unrelated population but of the same breed
decrease in the lifespan and loss of milk production in dairy cows
meat of such animals is tougher due to high pH
Inbreeding depression: decreased vigour and productivity and reduction in weight gain in the offspring.
ADVANTAGES
accumulation of superior genes
eliminates harmful or deleterious recessive genes
increases homozyosity (evolve pure line)
Step iv) The process is repeated for 4-6 generations
Step iii) Again,the superior males and females are identified from the progeny
Step ii) Assessment and evaluation of progeny obtained from such mating for desirable traits
Step i) Identification and mating superior males and superior females of the same breed in pairs.
higher growth rate
Longer productive life and higher reproductive rate
resistance to various diseases
Increased yeild and better quality of animal products like miks, eggs,meat and wool
step iv) Callus formation: CONTINUE
step iii)transfer of explants to culture medium under aseptic condition with optimum conditions for growth
step ii) Sterilisation (free from microbes) of explant,vessels,culture medium and all instruments using chlorine water or sodium or calcium hypochlorite solution
step i) selection of explant
iron-fortified rice
Wheat: Atlas 66
Maize hybrids
Okra(bhindi) Pusa Sawani, Pusa A- 4 Shoot and fruit borer
Flat bean Pusa sem 2, Pusa Sem 3 Jassids, Aphids and fruit borer
Brassica (rapeseed mustard) Pusa Gaurav Aphids
Chilli Pusa Sadabahar Chilly , mosaic virus, tobacco mosaic virus and leaf curl diseases
Cowpea Pusa Komal Bacterial blight
Cauliflower Pusa Shubhra, Pusa Snowball K-1 Black rot and curl blight, black rot
Brassica Pusa swarnim (Karan Rai) White rust
Wheat Himgiri Leaf and stripe rust, Hill Bunt
Viruses: tobacco mosaic
Bacteria : black rot of crucifers
Fungi: brown rust of wheat , late blight of poatato
when such hybrids are produced,they are better than parents and continue to be cultivated
better yeilding varieties in plants in terms of growth,size,climatic condition
indiviuals
reduced biological fitness in a given population because of interbreeding among related
genetically similar plants produce reccessive traits in their progeny
caonatins information:
validity of certificate
special features (if any)
absence of weeds and presnce of inert matter (not more than 1%)
purity of seeds (99%)
date of test
Seeds are certified and packed in sealed packects as certified seeds. Each sealed packet
National Seeds Corporation (NSC)streamlines raising seeds of improved varieties
high rate of germination
high order of purity
free of pathogens and pests
free of weed seeds
STEPS:
qualities and then F1 seeds can be directly grown
iii) Crossing the selected inbred lines to produce uniform F1 population with desired
inbred lines
ii) Selfing the selected plants through several generations to produce uniform homozygous
i) Selection of haploid plants that have the combination of desired characters
TYPES
Intergeneric: different genera
Interspecific: different species
Intervarietal: different lines or varieties of the same species
Intravarietal: same variety
STEPS
crosses show the desirable combination. such hybrid plants are sleceted
step 2: Not all hybrids show the desired characters. only, one in a few 100 to 1000
placed on stigma of flowers of female parents
step 1: pollen grains from the desirable plant chosen as male parent are collected and
PROCEDURE
pollination or crossing
tagging
bagging
emasculation (stamens removed at bud stage)
Selection and Isolation ofmplants
phenotypic characters
Clonal Selection
new genetic variability cannot be introduced
helps in conserving hybrid vigour and quality of crop
plants that multiply by vegetative propogation
Pure Line Selection
process repeated continously to obtain pure line
sown in separate rows
plants selected on basis of best agronomic characters
self pollinated crops
Mass Selection
the process is repeated many times to obtain homozygosity
plants selected for desired features and their seeds are collected
grown in same field
cross polinated plants
identified. selection is carried out for plants with advantageous charaters based on
The germplasm is evaluated and plants with desired combinations of characters are
Types of Seeds
Cyropreserved (-196° C)
Recalcitrant Seeds (aerobic humid conditions)
Orthodox Seeds (-10° to -20° C)
Centres for plant genetic resources
International
International Board of Plant Genetic Resources (IBPGR)
indian
Central Rice Research Institute(CRRI)
International Crops Research Institute for Semi-Arid Tropics (ICRISAT
crop and its wild relatives constitutes the germplasm
wild species related to the crop species
pur lines produced by plant breeders
old local or desi varieties
improved varities that are no mor in cultivation
all cultivated improved varieties
The sum total of all alleles of the genes present in the existing and past varieties of a
