You forgot about the height. It will overshadow the smaller crop, and lack of sunlight on this smaller crop may simply not produce any ears as a result. Just a "balcony farmer" but that is what i have seen with most plants that are overshadowed by dense/taller plants.

A good story that touches on this is the Wizard and the Prophet, covering Norman Borlaug's efforts to crossbreed wheat that wasn't too tall, was resistant to blight, etc.