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CHAPTER 5: DEVELOPMENT OF SEED AND FRUITS (DEVELOPMENT OF FRUITS…
CHAPTER 5: DEVELOPMENT OF SEED AND FRUITS
DEVELOPMENT OF SEED
After fertilization
diploid zygote, endosperm nucleus, associated maternal tissue
plant embryo encased called seed
monocot
dicot
Seed structure
seed along with ovule protected by seed coat
dicot
testa
tegmen
embryonic axis
plumule
radicle
hypocotyl
hypocotyl
portion of the embryo
seedling between root and cotyledon
radicle
root of embryo
testa
seed coat
plumule
consist
apical meristem
first true leaves of young
coleoptile
pointed sheath that protect the emerging shoots
scutellum
thin with high surface area
absorb nutrients from endosperm during germination
in monocotyledon
starch movement from endosperm to embryo
Part of typical seed
endosperm
cotyledon
absorbing organ
absorb food molecule
major portion of seed
embryo
plumule
hypocotyl
radicle
seed coat
seed coat
micropyle
small pore
near the funiculus
DEVELOPMENT OF FRUITS
Fruits
method
pollination and no fertilization
no pollination and no fertilization
flowers
pollination
fertilized
Fruits development
1) True fruits
developed after fertilization
ovary developed of the flower
ovary ripened grows into fruits
example
maize
grape
mango
2) False fruits
derived from florals parts other than ovary
example
peduncle
cashew nut
thalamus
apple
pear
fused perianth
rasberry
calyx
in Delinnia
3) Parthenocarpic
seedless fruits formed without fertilization
example
pineapple
banana
Morphology of fruits
consist
seed
fertilized
ripened ovule
pericarp
developed from ovary wall
dry
fleshy
differentiate
middle mesocarp
inner endocarp
epicarp
Types of fruits
1) Simple fruits
process
developed from each carpel
developed from single ovary of single flowers
types
dry
fruits are not fleshy
pericarp not distinguished into 3 layers
succulent (fleshy)
fruits are indehiscent
seeds are liberated after the flesh decay
distinguished
epicarp
mesocarp
fleshy or fibrous
endocarp
example
nuts
beans
2) Aggregate fruits
process
developed from one carpel that fuse together
all are in the saame flower
example
rasberry
3) Multiple fruits
process
develop from cluster of flowers
flowers fuse together to form the fruits
example
pineapple
4) Accessory fruits
process
developed from ripened ovary
has tissue derived from part of the plant outside of the ovary
some flesh is not derived from the ovary
formed another part of flower
example
receptacle
strawberry
hyphantium
apples
pears
Parthenocarpy
Explaination
productions of fruits without fertilization of ovules
do not produce any viable seeds
artificial or natural production of fruits
Causes
lack of pollination
pollination occur but fertilization does not
fertilization followed by embryo (seed) abortion
Types
1) vegetative parthenocarpy
lack of pollination
fruits developed without stimulus of pollination
no seed formed
example
pear
fig
2) stimulus parthenocarpy
pollination occur but fertilization does not
example
grapes
3) stenospermocarpy
fertilization followed by embryo
seedless fruits
most commercial fruits used gibberelin to increase the size of fruits
example
watermelon
Artificial parthenocarpy
hormone to induce parthenocarpy
auxins
treatment of young fruits
unpollinated ovaries
gibberelins
producing seedless grapes
prevent premature droppping of fruits
cytokinins
stimulate with pollen
pollen presents incompatible with female flowers
pollen tube enter embryo sac
male gamete does not fertilize the egg cells
pollen tube disappear but can stimulus the fruits
Benefits
improve quality
plant growth regulator to natural
reduce costs
keep the insects and pests away
Parthenogenesis
1) diploid parthenogenesis
produce seed with 2n embryo
caused by megaspore mother cell 2n
developed into embryo 2n without fertilization
2) haploid parthenogenesis
produce seed with haploid embryo
development of egg become haploid embryo without fertilization
Apoximis
asexual formation of seeds from the maternal tissue of the ovule
no meiotic division
seed generated from somatic cells
need to
the process