This question is about naming the type of crop interaction that happens in a legume plus non-legume intercrop, where one partner adds a benefit rather than competing.
- Annidation: This term describes crops separating out in space or time, for example one rooting deeper than the other, so they draw on different parts of the same resource pool. It reduces competition but is not the same as one crop actively supplementing the other.
- Allelopathic: This describes one plant releasing chemicals that suppress or harm a neighbouring plant, which is a harmful interaction, not a helpful one.
- Antagonism: This is a general term for a harmful or competitive relationship between two crops, the opposite of what supplementation means.
- Supplementary: In a legume and non-legume mixture, the legume fixes atmospheric nitrogen and this extra nitrogen supplements the non-legume's nutrient supply, without the legume losing anything or competing for the same soil nitrogen pool. This directly matches the idea of one crop supplementing the other.
Because the legume's nitrogen fixation adds a resource rather than dividing up a fixed one, this interaction is named the supplementary effect, and it is the correct match for the question.
Let's summarize:
- Supplementary effect means one crop provides a net benefit to the other without a matching cost to itself.
- Annidation, allelopathy and antagonism describe resource separation, chemical harm and competitive harm respectively, none of which match plain supplementation.
So the correct term for this legume and non-legume interaction is supplementary.