the crop where hybrid vigour has been utilised most is-

1. rice
2. maize
3. barley
4. oat

the crop where hybrid vigour has been utilised most is maize.
The increase in the level of production traits due to crossing is called hybrid vigour or heterosis. The term hybrid vigour points at the vigour, which is a real factor that can bee seen by the naked eye, in comparison to pure breeding. The other word heterosis is derived from heterozygosity and points toward the direction form where the effect arises. The direction of the effect of crossing is opposite the effect of inbreeding.