Breeding of Vegetable, Spice and Tuber crops (2+1)

Cross- pollination

• In cross-pollinating species, the transfer of pollen from a flower to the stigmas of the others may be brought about by wind (anaemophily), water (hydrophily) or insects (entomophily). Many of the crop plants are naturally cross-pollinated. In many species, a small amount (upto 5-10 per cent) of selfing may also occur.Mechanism promoting cross pollination: There are several mechanisms that facilitate cross pollination. They are

Dicliny

• Dicliny or unisexuality is a condition, in which the flowers are either staminate (male) or pistillate (female). Dicliny is of two types
i) Monoecy and
ii) Dioecy

Monoecy

• Staminate and pistillate flowers occur in the same plant separately e.g., cucurbits
Dioecy

• The male and the female flowers are present on different plants e.g., spinach

Dichogamy

• In the same hermophordite flower stamens and pistils may mature at different times, thereby hindering self pollination eventually facilitating cross- pollination.

Dichogamy is of two types

• Protogyny: The pistils mature before stamens
• Protandry: Stamens mature before pistils

Self incompatibility

• It refers to failure of pollen from a flower to fertilize the same flower or other flowers on the same plant. Self-incompatibility is of two types; sporophytic and gametophytic. In both the cases, flowers do not set seed on selfing. Self-incompatibility is common in cauliflower and radish. It is highly effective in preventing self-pollination.

Male sterility

• It refers to the absence of functional pollen grains in otherwise hermaphrodite flowers