2. Unfruitfulness
• The inability of plants to produce a
commercial crops is called --------
• Many factors are responsible for the
inability to produce fruit and viable seeds
• It could be due to inherited characteristic
• Some variety of popular and ornamental
variety of banana never produce flower
3. Unfruitfulness
• some agronomic crops (sugarcane) rarely
flower some produce in rare condition
• Some flower produce flower but fails to set
and produce the seed
• Gross Michel Banana flowers and set the
fruit but seed less
4. Unfruitfulness and Sterility
Associated with Internal factors
• It is due to impotence / weakness or power
less or nonfunctional of organs
• These can be classified as
5. Unfruitfulness and Sterility Associated
with Internal factors
(Process in which species are developed )
Those fruit plant which are cross pollinated have some
weakness in their structure or in performing the function
are associated with self unfruitfulness and self fertility
A. Due to evolutionary tendencies
B. Recent genetic influences
C. Physiological influence
A- Due to evolutionary tendencies
6. A-1 Sex expression/ distribution
• Dioecious
date palm, papaya, pistachio
Some conditions citrus, straw berry,
persimmon and banana also produced
female flowers
Mangosteen- only pistil but produce flower
with out pollination that is parthenogenesis
7. A-1 Sex expression/ distribution
• Pseudohermaphrodite flowers
- Non functional
e.g asparagus, alpine currant, some
varieties of grape, pomegranate ,
japanese persimmon
8. A-1 Sex expression/ distribution
• Monoecious
Unisexual flowers but present on same
plant
e.g. Hazal nut, walnut , chestnut
9. A-1 Sex expression/ distribution
• Mixed flowers
some pistillate and staminate bear at
the same some perfect but some
pseudo-hermaphrodite
E,g several citrus, limon, aurentifolia ,
medica, grandis , paradisi, reticulata,
10. A-2. Structural Device
• Heterostyled-
– Style is small filament is long
– Long style and short filament
– Flowers of long styled and short filament are
largely unfruitfulness due lack of pollination
or incompatibility
– e.g. varieties of apple, pear , citrus
11. A-3 Abortion of flowers, pistils and
stamens
• Abortion of flowers, stamens and pistils,
In imperfect flowers ---
flower bud abortion in grapes cluster
pistil abortion in plums
pistil abortion may early in flower development
may or after opening
Failure of fruit set in pomegranate and citrus
It is also common in strawberry
12. A-3 Abortion of flowers, pistils and
stamens
• In banana in middle cluster the flowers
have stigma but no style
• In pear and apple ovule collapse with any
appearing changes in stigma and style. No
much information about this defect
• Satsuma and Washington navel and
oranges abortion before gametophyte
13. Abortion stamens
• Some cases complete and partial abortion
of stamens are common
• Varieties of plums pseudo-hermaphrodite
because their stamen do not produce
pollen
• Pollen sterility is problem, its viability in
different in fruits
14. Abortion stamens
• In wild black berry pollen abortion is less
than 10- 90 percent according the variety
• 50% pollen abortion poor results above
this
• In mango defect pollen are 2-10 percent
• In apple and pear defective pollen are
15. A-4. Protandry
• Dichogamy --
• Chestnut- pistils are born in current year growth
but staminate in both but -----
• Pecan varieties --------
• Litchi------
• Some orange varieties -----
• Some times are different ---
• Mango stigma remains receptive for few hours -
16. 4-A Protandry
• Avocado– flowers open two time with and
intervolving close period. 1st opening
flowers remains opened for few to 13
hours approximately
• 1st opening –pollen shed but ------
• 2nd opening –stigma receptive but -----
• Same problem in apple
solution
(interplant ion)
17. 4- Protandry
B- Due to Genetic Influence
1- Hybridity
2- Incompatibility
C- Due to Physiological Influence
1- Slow pollen tube growth
2- Pre-mature and delayed pollination
3- Nutritional conditions with in the plants
4- Age and plant vigour
18. Unfruitfulness and Sterility Associated
with external factors
1- Under stock or grafting
2- Pruning
3- Temperature
4- Soil moisture and atmospheric humidity
5- Light
6- Climatic season and locality
7- Miscellaneous
