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Farmers who want to reduce high input costs face a decision at planting time: How many seeds per acre to put in the soil? Planting fewer seeds per acre saves money up front, but how does plant population affect yield?
The optimum density or plant population for any given situation results in mature plants that are sufficiently crowded to efficiently use resources such as water, nutrients, and sunlight, yet not so crowded that some plants die or are unproductive. At this population, production from the entire field is optimized, although any individual plant might produce less than would have occurred with unlimited space.
Many factors influence the optimum plant population for a crop: availability of water, nutrients and sunlight; length of growing season; potential plant size; and the plant’s capacity to change its form in response to varying environmental conditions (morphological plasticity). One example of this is tillering, which allows small grain crops like winter wheat to produce the same number of heads and final grain yield in a given area over a wide range of plant densities. Modern corn cultivars, on the other hand, have been selected to produce few if any tillers. Consequently, corn has a relatively narrow range for optimum plant population.