58 MTBIOLOGY TODAY | JULY ‘15• Humming birds are the most common group of flower
visiting birds in America. Honey creepers are common
pollinators in Africa and Asia. Humming birds are mostly
attracted to bright red coloured, odourless flowers.
• Flowers pollinated by insects/birds can be grouped into
three categories depending upon the benefits (rewards)
which they provide to the pollinators :- Food providing flowers, e.g., Salvia and bees,
humming birds and Bignonia, sun birds and Strelitzia. - Sex providing flowers, e.g., Ophrys and Colpa
wasp. - Nursery providing flowers, e.g., Yucca and yucca
moth, fig and wasp.
Chiropterophily
• Pollination of flowers by means of bats is called
chiropterophily. Bat pollinated flowers are dull-coloured
with strong fermenting or fruity smell, abundant nectar
and pollen grains. Examples of chiropterophilous plants
are Kigelia, Adansonia, etc.
Malacophily
• Pollination by snails is called malacophily. This type of
pollination is seen in some plants such as Lemna, Aroids,
etc.
Myrmecophily
• It is the pollination of flowers by means of ants, e.g., some
members of family Rubiaceae.Significance of pollination
- Pollination is a means of taking the male gametophyte
for its growth near the female gametophyte. - Pollen-pistil interaction determines the suitability
of pollen for carrying out the process of sexual
reproduction. - It has freed the seed plants from the dependence on
external water during fertilisation. - It can be manipulated to produce pure lines as well as
desired varieties.
• After successful pollination, pollen germinates on stigma
followed by the process of fertilisation. Fertilisation
eventually leads to development of seeds containing
embryo.
• Some of the methods currently used for pollen storage are as follows :- Dry and Cold storage : Sub-freezing temperatures (–5°C to – 10°C) and low relative humidty (25 to 50%) have
generally proved optimum for storing pollen in viable condition. - Cryogenic storage: Application of cryogenic technique (storage in liquid nitrogen, at –196°C) to preserve pollen viability
for prolonged duration has been found suitable for several economically important crops. At –196°C pollen undergo
negligible metabolic changes in terms of physiological and biochemical processes which otherwise might render them
inviable. This method has also been recommended for convenient and economical storage and transport of germplasm. - Organic solvents : Acetone, benzene, ethanol, ether, chloroform and phenol, are generally regarded as toxic to
organisms. However, it has been demonstrated beyond doubt that pollen grains kept in these organic solvent can
germinate in vitro and even effect fertilisation. (Iwanami et al, 1988).
• Some of the practical applications of pollen storage are: - To hybridise plants that flower at different times and locations or show non-synchronous flowering.
- To provide a constant supply of short-lived (recalcitrant) pollen.
- To facilitate supplementary pollination for improving yield.
- To eliminate the need to grow male lines continuously in breeding programmes.
- To ensure the availability of pollen throughout the year without using nurseries or artificial climate growth rooms.
- To study pollen allergens and the mechanism of self-incompatibility.
- Long-term germplasm storage, especially of unique genotypes.
pollen storage
- “Geitonogamy is genetically equivalent to self pollination but ecologically it is cross pollination”. Justify
this statement. - Give two characteristic features of entomophilous flowers.
- How is malacophily different from myrmecophily?