There are several methods to overcome plant incompatibility, including mixed pollination, bud pollination, stub pollination, and intra-ovarian pollination. Mixed pollination involves pollinating the stigma with a mixture of live incompatible and killed compatible pollen. Bud pollination works in some plants where pollination at an early bud stage can overcome incompatibility. Stub pollination removes part of the style to allow the pollen tube to reach the ovary in plants where incompatibility is restricted to the stigma. Intra-ovarian pollination introduces pollen directly into the ovary to fertilize it.

1. METHODS TO OVERCOME
INCOMPATIBILITY :
There several methods to overcome
incompatibility.
They are,
• Mixed population,
• Bud pollination,
• Stub pollination, and
• Intra-ovarian pollination.

2. MIXED POLLINATION :
• In this method, the stigma is disguised from
recognizing the incompatible pollen by pollinating it
with a mixture of live incompatible pollen, and
killed(by chemical or radiation) compatible
pollen(termed Mentor pollen or Recognition pollen).
• By employing recognisition pollens, self
incompatibility has overcome in Cosmos (Howlett et
al.,1975) and Petunia hybrida (Sastri and
Shivanna.,1975) and interspecific incompability in
genus Populous(Knox et al.,1972).

3. BUD-POLLINATION :
• In some plants, pollination at an early bud
stage has proceed very effective in
overcoming intraspecific incompatibility.
• At the bud stage (before anthesis), the stigma
lacks the exudate to inhibit pollens and by
chance pollination at that stage may effect
fertilization.

4. STUB-POLLINATION :
• In some plants incompability may be
restricted to the stigma or the style is too long
and the pollen tube could not reach the ovary.
• In this case, removal of stigma and part of
style before pollination may prove helpful in
overcoming incompatibility.

5. INTRA-OVARIAN POLLINATION :
• In this technique, the ovary surface is sterilized
with ethanol and two punctures are made in the
wall- one for introducing the pollen suspension
and the other to permit the escape of of air in the
ovarian cavity( Kanta et al.,1962).
• Variable seeds following intra-ovarian pollination
have obtained in several members of
Papaveraceae such as Argemone mexicana, A.
ochroleuca, Papaver somniferous and P. rhoeas.

6. 1. HEAT TREATMENT OF STYLE :
Moderately high temperature (up to 50 C) are
known to reduce the self-incompability reaction in
certain plants. e.g. Lilium longiflorum (Hooper et al
1967).
2. IRRADICATION :
• Induce temporary breakdown of incompatibility
reaction (Pandey, 1963), or alteration of the
inhibitory substances in the style(Kumar and
Hecht,1965). Irradication helpful in those systems
where process are controlled gametophytically.

7. 3. CHEMICAL TREATMENT :
Application of certain chemicals may prolonged the life of
flowers (Choudhury 1965). Oenothera species by the
application of p-chloromercuribenzoate. Hodgdon and
Hetch(1975).
4. PARASEXUAL HYBRIDISATION : In 1969 a new
approach was proposed to raised such hybrid which
could not be produced through the conventional
method of hybridization because of sexual
incompatibility. This technique involves fusion of
isolated protoplast of somatic cell and is described as
parasexual hybridization. This involves the following
step :- (a)Isolation of protoplasts. (b)Fusion of isolated
protoplasts. (c)Cultured of hybrid protoplasts to
regenerate whole plant.

8. TECHNIQUES FOR OVERCOMING
POST-FERTILIZATION BARRIERS
• A range of in vitro methods have been developed to
overcome post-fertilization barriers in
• a number of plant species.
• When abortion occurs in a very young stage and
maternal tissue has no negative influence on the
development of seeds, ovary culture can be applied:
young fruits can be grown in vitro to a stage at which
dissection of embryos is possible.
• In some crops, the ovary is large and slicing the ovary in
small parts and influencing them, is a better option for
rescuing theb young seedlings in vitro.

9. Cntd…
• This technique is referred to as ’ovary slice culture’.
• When the mismatch between embryo and
endosperm development starts very early and
ovary culture and/or ovary slice culture fails,
ovules can be dissected out of the ovaries and be
cultured in vitro.
• If young fruits7 can stay for a longer time on the
mother plant, embryo rescue can be applied by
different methods: in ovulo rescue and embryo
rescue.
• Since Hännig (1904) employed embryo culture for
the first time 90 years ago, these techniques are
applied in numerous crops (Williams et al. 1987).