6. โข The offspring that is obtained by crossing two genetically dissimilar
homozygous parents is called hybrid and the process of producing
hybrid is called hybridization.
โข Yuan Longping, the "Father of Hybrid Rice", may be the most
famous in research on hybrid rice. In the 1970 s, he made his
discovery of the genetic basis of heterosis in rice. This was a unique
discovery because it had been previously thought that heterosis
was not possible for self-pollinating crops such as rice.
7. Objectives
โข To create variability
โข To increase the yield of grain
โข To increase grain quality
โข To develop early maturity variety
โข To develop disease resistant variety
โข To develop insect and pest resistant variety
โข To improve cooking characteristics
9. FLORAL BIOLOGY
โข Terminal panicle which bears perfect flower.
โข Sessile,bi-sexual,self pollinated flower.
โข Flower having six stamens.
โข Flower surrounded by lemma and palea.
โข Gynocium consists of carpel-1,superior ovary and one chambered
hypogynous.
โข Most of the flowers bloom between 2-4 days.
โข Blooming of the spikelets starts from panicle apex and proceeds
downward.
โข Pollen shed at the time of flower opening.
โข Stigma remains receptive for 4-5 days.
โข Pollen preservation possible for 24 hours at 54 degree F at 95% humidity
โข Fertilization completes within 3 hours after pollination
12. 1. Selection of female plants
โข Insect and disease free healthy plant
โข Selection of flowers expected to open by next morning
โข Removal of immature and open flowers
13. 2. EMASCULATION
โข Purpose of emasculation to prevent pollination
โข Selection of panicles expected to open in the morning
โข Selection of spikelets whose anther length about 60%
โข Lemma and palea need to cut at a place 20% bellow from the tip
โข Stamens need to remove one by one with sterized needle or forceps
โข Best time : afternoon
โข Bagging of emasculated flowers with polythene
16. Mechanical
emasculation
๏ถ Mechanically
prevented of pollen
transfer
๏ถ Time saving,
extensive,quite cheap
๏ถ vacuuming of anthers
involves an aspirator
and high speed suction
of pollen from the
anthers of flowers with
a minimum damage to
the stigma.
17. 3. POLLINATION
โข Process of collecting anther and pollen grains of desired male parent and
putting in the stigma at the emasculated flower of desired female parent
โข Done in the next morning when the stigma is receptive
โข Collection of yellow and turgid anthers from desired male plant and
putting them in bright sunlight for 15 minutes
โข Temporary removal of bag from female plants and pollination is done by
dusting pollens over stigma surface of emasculated buds
โข Sometimes whole anther is inserted inside the florets with the help of
forceps
18. BAGGING
โข Fixation of bamboo stick
โข Top of the plants with bud inside the bag
โข Two james clip through holes
โข Exchanges of gases
โข Stop the visit of insect
19. TAGGING
โข After bagging tag bear following information:
๏Cross combination (BR3 x BRRI dhan 29)
๏Date of emasculation
๏Date of pollination
๏Numbers of buds pollinated
๏Signature of the breeder
20. โข In agriculture, it is vitally important to maintain genetic diversity to
obtain the health and longevity of a crop.
โข As with other types of hybrids, hybrid rice typically displays
heterosis
โข Green Revolution popularized the use of conventional
hybridization to increase yield by creating "high-yielding varieties".
โข Often the handful of hybridized breeds originated in developed
countries and were further hybridized with local varieties in the rest
of the developing world to create high yield strains resistant to
local climate and diseases