Castration of Plants

the removal of immature anthers from a monoecious flower in order to prevent possible self-pollination; an essential technique for hybridizing plants capable of self-pollination.

The anthers are usually removed with tweezers, sometimes with special needles or small scissors. Plants are castrated, as a rule, in the bud stage one or two days before the pollen and stigma of the pistil are ready for pollination. In cereal grasses, only some of the flowers are castrated because of the uneven development of the flowers in the ear (or head). In wheat, the flowers in the center of the ear are castrated and all the others are removed; in the awned varieties, the awns are also removed.

When a plant is castrated, the ear is held in the left hand while the flowering glumes are drawn apart with tweezers and the anthers cut out. A special effort is made to avoid harming the stigma of the pistil or leaving individual anthers or parts of them (if there are only a few anthers, they should be tabulated as a control).

Gauze or parchment bags (insulators) are immediately placed over the castrated flowers or racemes and tied below the flower or raceme on the stem after first wrapping it in cotton. The gauze insulators prevent the castrated flowers from coming into contact with pollen carried by insects, and the parchment insulators provide protection against wind-born pollen. The insulators are left on the flowers or racemes for some time after pollination. To check the quality of castration, some of the castrated flowers are left in the bags without pollination. Castrated flowers are not insulated when there is free pollination of the plants.

Cereal grasses with small flowers (millet, foxtail millet) are castrated thermally: the heads are immersed in hot water (45°-50°C) for four to five minutes to render the pollen inviable.