Why does self-incompatibility not lead to seed formation in self-incompatible species ?

What is self-incompatibility? Why does self-pollination not lead to seed formation in self-incompatible species?

What is self-incompatibility? Why does self-pollination not lead to seed formation in self-incompatible species?

What is self-incompatibility ?

Why does self-fertilization not occur in earthworm?

SHORT ANSWER TYPE QUESTIONS Does self-incompatibility impose any restrictions on autogamy? Give reasons and suggest the method of pollination in such plants?

How does saliva act in self-defence?

Give reasons,why? Nitrogen deficiency leads to formation of purple colour in stems etc.of some plants.