The mango inflorescence is primarily terminal, although axillary and multiple panicles may also arise from axillary buds. Both perfect (hermaphrodite) and staminate (male) flowers occur in the same inflorescence. The total number of flowers in a panicle may vary from 1000 to 6000, depending on the cultivar (Mukherjee, 1953). Initial fruit set in mango is directly related to the proportion of perfect flowers, although the final fruit set does not necessarily depend on this ratio (Iyer et al., 1989). It appears that the proportion of perfect flowers in a cultivar becomes critical for optimum fruit set only when the proportion drops to 1%.
Flowers begin to open early in the morning and anthesis has generally been completed by noon. The greatest number of flowers opens between 9 and 10 a.m. Although the receptivity of the stigma continues for 72 h after anthesis, it is most receptive during the first 6 h; however, there are reports that the stigma can become receptive even before anthesis has occurred (Singh, 1960). The minimum time required for pollen grains to germinate is 1.5 h (Sen et al., 1946; Singh, 1954; Spencer and Kennard, 1955). Singh and Singh (1952) observed 98% pollen viability after 11 months in storage at 7°C and 25% relative humidity (RH), and 65.7% viability after 24 months of storage at 0°C and 25% RH.
Mango is cross-pollinated, which is carried out by insects such as the common housefly, honeybees and thrips, and possibly by other insects al-though to a lesser extent. Pollination by wind and gravity has been suggested to occur in mango (Popenoe, 1917; Maheshwari, 1934; Malik, 1951). In nature, > 50% of flowers do not receive any pollen. Some workers had suggested that self-pollination in certain cultivars can also occur quite frequently (Dijkman and Soule, 1951). Studies by Issarakraisila and Considine (1994) have shown that for polyembryonic 'Kensington', a night temperature of < 10°C results in pollen grains with low viability (< 50%). The optimum temperature for normal meiosis is between 15 and 33°C with 70-85% viability.
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