Unfortunately there is no simple answer to the above question. Usually fields that are planted at too high of a population have greater lodging, poorly filled ear tips and a greater number of barren plants. Some hybrids tolerate high populations better than others.
Maturity is important.
Need plenty of moisture for higher populations to be advantageous. The main problems encountered by plants in overplanted fields are problems associated with drought conditions and the hybrid's ability to withstand stress. However, the yields of well-fertilized corn do not fall off very sharply when population is above the optimum, even in dry years . The number of ear bearing plants is usually more important than the weight of the ears. Another indicator of too high a population is an abnormal number of barren plants.