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barriers to fertilisationincompatibility can occur anywhere from pollination to syngamy and consequently obstructing fertilisation the pollen fails
homomorphic types - intra specific incompatibilityit is characterized by morphologically indistinguishable mating types within a species a proper
s-genethe s-gene has been suggested to be a super gene complex with several linked genes it is supposed to have at least six may he more
heteromorphic types - intra specific incompatibilityplants of the same species produce flowers that differ in morphology this involves two distyly or
incompatibility - pollination and fertilizationplants growing under natural conditions have a preference for their mating partners the stigma of the
triple fusionthe fusion process between the other male gamete and the secondary nucleus follows the same pattern as syngamy in most plants the polar
syngamythe pollen tube grows to a very limited extent in the synergid it releases the contents either through a terminal or a subterminal pore the
pollen tube growth there are significant differences in the fine structure of the tips of pollen tubes in compatible and incompatible pistils such as
entry of pollen tube into the embryo sacthe pollen tube enters the embryo sac through the filiform apparatus of ong of the synergids generally one of
syngamy and triple fusion after traversing through the stylar region the ultimate destination of the pollen tube is to reach the female gametophyte
fine structure of pollen tubes grown in vitro the growth in pollen tubes is exclusively restricted to the tip cytochemical analysis reveals the
pollen tube structure the pollen tube in the stigma is filled with cytoplasm containing numerous mitochondria and dictyosomes the number of
respiration - metabolism of pollen tubes in the unpollinated pistils of hippeastrum hybridum very high o2 tension exists from stigma down through
metabolism of pollen tubes pollen grains contain auxins and gibberellins which are known to be involved in post- pollination enlargement of the ovary
passage of pollen tubein cotton the pollen produces a tube within an hour which grows on the surface of the stigmatic hairs and then between the
closed style - style of stigma interactioncotton shows an epidermis with stomata a cortex of thin-walled parenchyma with several vascular bundles and
open style - style of stigma interactionaegle fritillaria lilium spp have variable number of stylar canals depending on the number of carpels the
style of stigma interactionthe style has been distinguished into two types in open styles a stylar canal is present which is lined with a
dry stigma - category of stigmathe cotton gossypium hirsutum stigma is covered with long unicellular hairs at the time of pollination the stigmatic
wet stigma - category of stigmapetunia shows several randomly distributed 2-celled papillae on its surface in a developing stigma the epidermis is
pollen stigma interaction - stigmathe stigma after landing on the stigma pollen grain germinates and produces a pollen tube that carries the male
self- vs cross-pollination a major advantage of self-pollination is its certainty continued self-pollination over many generations however results in
benefits of cross-pollinationbecause of the specific benefits of cross-pollination flowering plants have evolved many devices to prevent
chiropterophily - cross-pollinationpollination brought about by bats is called cheiropterophily bats which feed at night and do not see very well are
ornithophily - cross-pollinationin tropical areas the birds dominate over insects as important pollinators the most common among them are