What are outbreeding devices? Describe them. Explain how a plant breeder makes sure that only the desired pollen reaches the stigma.

1. 1 · Define in one line. Outbreeding devices are features of flowers that discourage self-pollination and encourage cross-pollination, preventing inbreeding depression.
2. 2 · List the devices with examples.
   • Pollen release and stigma receptivity not synchronised.
   • Anther and stigma at different positions.
   • Self-incompatibility, a genetic block on self-pollen.
   • Unisexual flowers: monoecious castor and maize prevent autogamy; dioecious papaya prevents autogamy and geitonogamy.
3. 3 · Introduce artificial hybridisation. Breeders cross chosen parents and must keep out unwanted pollen.
4. 4 · Emasculation. Remove the anthers of a bisexual flower bud of the female parent with forceps before they dehisce.
5. 5 · Bagging and pollinating. Cover with a butter-paper bag; when the stigma is receptive, dust pollen from the male parent and rebag. For unisexual flowers, skip emasculation and bag the female buds before they open.
6. 6 · Link to daily life. Hybrid seeds of crops like maize and cotton come from such controlled crosses.
7. 7 · Close in one line. So nature uses outbreeding devices, and breeders use emasculation and bagging, to control which pollen reaches the stigma.

Scoring tip: Give an example with each device. Castor or maize for monoecious, and papaya for dioecious, are the examples examiners expect.