Response of Corn (Zea mays L.) to Population Pressure1

The response of field and sweet corn (Zea mays L.) to population pressure was investigated using square and row spacing arrangements with population levels ranging from 2,375 to 151,957 plants per ha (961 to 61,496 plants per acre). Grain yield per unit area peaked at a finite population level, while total top yield appeared to be asymptotically related to plant population. Of the various models tested only the “modified reciprocal” equation w −θ = Ap + B, where w = yield per plant, p ‐= plant population, and θ, A, and B are constants, adequately described the response of both grain and total top yield per plant to changes in plant density. The constant θ can be estimated using α from the relation Wtotal = Wαgrain as yield changes with plant density. The constant α may be useful both as a selection criterion in breeding for increased yield and as a parameter in population and plant distribution studies.