A B.Sc. (Hons.) Agriculture student from NPI in Nepal created and delivered the presentation. This slide describes the floral morphology and plant reproduction. It also describes the asexual, sexual, and vegetative reproduction of the plant.

1. Modes of Reproduction in Crop Plants
Presenter:
Suman Ghimire
B.Sc.Hons (Ag.) 7th semester, Roll no.: 88
Bharatpur-11, Chitwan

2. Mode of reproduction
• Reproduction: most important phenomena necessary for continuation
of species from one generation to another
• Mode of reproduction: determine the genetic constitution of crop plant
and provides the basis for understanding the mechanism of heredity,
which are required for handling the desired characters during breeding
work
• Sexual and asexual reproduction are two modes of reproduction
• Sexual reproduction is the source of recombination
• Asexual reproduction produces offspring same as parent

3. A) Sexual reproduction
• Multiplication of plants through embryos
which have developed by fusion of male
and female gametes is known as sexual
reproduction
• In crops, male and female gametes are
produced in specialized structures called
flowers
• A flower is a reproductive unit in the
angiosperms; it is meant for sexual
reproduction
• It involves: sporogenesis, gametogenesis,
pollination and fertilization Fig: Structure of flower

4. 1) Sporogenesis (Meiotic division)
• Process of formation of spore is k/a sporogenesis
• It may be microsporogenesis (formation of
microspores or pollen grains) or megasporogenesis
(formation of megaspore)
• Microsporogenesis occurs inside the pollen sac of
anthers
• Megasporogenesis occurs inside the nucellus of ovules

5. 1.a) Microsporogenesis
• Each anther has four pollen sacs,
which contains numerous pollen
mother cells (PMCs)
• Each PMCs undergoes meiosis to
produce four haploid cells or
microspores
• This process is k/a
microsporogenesis
• The microspores matures into pollen
grains mainly by a thickening of
their walls Fig: Microsporogenesis

6. 1.b) Megasporogenesis
• This occurs in ovules
• A single cell in each ovule
differentiates into a megaspore
mother cell
• The megaspore mother cell
undergoes meiosis to produce four
haploid megaspores
• Three of the megaspores degenerate
leaving one functional megaspore
per ovule
• This completes megasporogenesis.
Fig: Megasporogenesis

7. 2) Gametogenesis (Mitotic division)
• The production of male (microgametogenesis) and female gametes
(megagametogenesis) in the microspores and the megaspores, respectively
2.a) Microgametogenesis
• The process of development of
male gametes in the
microspores or pollen grains is
termed as micro gametogenesis
• In flowering plants it occurs
with a microspore mother cell
inside the anther of the plant
2.b) Megagametogenesis
• The development of embryo
sac from a megaspore
• The embryo sac generally
contains one egg cell, two
synergids, three antipodal cells
(all haploid), and one diploid
secondary nucleus

8. Contd. . .
Fig: Microgametogenesis
Fig: Megagametogenesis

9. 3) Pollination
• The transfer of pollen grains from anther of stamen to stigma of carpel
is k/a pollination
• The pollination may take place inside a flower (autogamy) or in
between two flowers (allogamy) of same plant (geitonogamy) or of
different plants (xenogamy)
• It is of two types:
a) Self pollination
b) Cross pollination

10. 4) Fertilization
• The fusion of one of the two sperms with the egg cell, producing a diploid
zygote, is k/a fertilization (discovered by Strassburger in 1884)
• The fusion of the remaining sperm with the secondary nucleus, leading to
the formation of a triploid primary endosperm nucleus, is termed as triple
fusion
• The zygote divides mitotically to produce a diploid embryo & the primary
endosperm nucleus produces endosperm through repeated mitotic divisions
• During seed development, endosperm provides nutrition to the developing
embryo
Note: Double fertilization was discovered by Nawaschin (Russian biologist) in 1898 in liliaceous
plants, Lilium martagon and Fritillaria tenella

11. Contd. . .
Fig: Pollination and Fertilization
Fig: Process of fertilization

12. Significance of sexual reproduction
• Sexual Reproduction produces variable offspring; it creates diversity
and variation among populations
• It is important for plants as it provides variation to the progeny
• Sexual reproduction helps in better survival of progeny
• It helps progenies to gain its own uniqueness within the species and
remove the unwanted genes

13. Contd. . .
• Sexual reproduction makes it possible to combine genes from two or
more parents into a single hybrid
• For example: we need a tall plant with blue flowers in a single plant,
so for this we will cross the plant which is tall with the plant having
blue flowers
• During sexual reproduction the genes of both plants combine and we'll
get some progeny with desired characters (tall plant with blue flower)

14. B) Asexual reproduction
• It is the formation of new individuals through asexual reproduction
without involving the formation and fusion of gametes
• It is of two types:
1. Apomixis: Seeds are formed but the embryos develop without
fertilization
2. Vegetative Reproduction: New plant develops from a portion of the
parent plant

15. 1) Apomixis
Basis of Classification Types of Apomixis Brief description
i)Cell involved Parthenogenesis Embryo develops from egg cell
Apogamy Embryo develops from either
synergids or antipodal cells
Apospory Embryo develops from the
embryosac which has developed
from the cell of
archisporeum/nucellus or
integument
Adventive Embryony Embryo develops directly from
the diploid cell of either nucellus
or integument
ii)Occurrence Recurrent Apomixis Embryosac has diploid cells and
embryo develops from diploid
cells
Non-Recurrent Apomixis Embryosac consists of haploid
cells and embryo develops from
haploid cell

16. Contd. . .
Basis of Classification Types of Apomixis Brief description
iii)Frequency Obligate Apomixis The reproduction occurs by
apomictic means only
Facultative Apomixis The reproduction occurs by both
sexual and apomictic means

17. Advantages of Apomixis
• It produces seed progeny which are exactly the same as the mother
plant; it helps in the preservation of good characters over generations
for crop plants
• It helps in the production of hybrid seeds with a combination of
desirable characters
• It also prevents the loss of specific characters from a hybrid
• It helps in the cost-effective and time-efficient production of seeds

18. Disadvantages of Apomixis
• Can't control accumulation of deleterious genetic mutations
• Usually restricted to narrow ecological niches
• Lack ability to adapt to changing environments
• Estimation of the level of facultative apomixis is tedious and time
consuming

19. 2) Vegetative reproduction
Vegetative Propagation
Natural Vegetative Artificial Vegetative
Root Leaf Stem Micropopagation
Grafting
Layering (Mound
layering and Air
layering)
Cutting

20. Advantages of Vegetative propagation
• Quicker and more certain
• Produces identical quality as the parent
• Plants that do not have viable seed, can be reproduced
• Flowers produced are of superior quality
• Desirable character of fruit can be maintained

21. Disadvantages of Vegetative propagation
• Does not produce new variety
• Leads to overcrowding around the parent plant
• Very little possibility of dispersal
• New plants are less varied
• New plants may be less adaptable to changes in environmental
condition

22. Acknowledgement
I would like to express my special thanks of gratitude to our respected
teacher, Mr. Mohan K. Bista (Asst. Professor; Genetics and plant
breeding) who gave me the opportunity to do this wonderful
presentation on the topic, Mode of Reproduction in Crop Plants, which
also helped me doing a lot of research & I come to know about so many
new things.
Secondly, I would also like to thank my family & friends who
helped me a lot in finishing this presentation within the limited time.
THANKS AGAIN TO ALL WHO SUPPORTED

23. And this brings us to the end !!!
I’d like to thank you for your time and attention today !!!
If anyone has any questions, please feel free to ask now
and I’ll do my best to answer !!!