Timing, Effect, and Recovery from Intraspecific Competition in Maize

In production agriculture, it is not uncommon for a crop to experience both intra‐ and interspecific competition during the normal course of development. Although the competition between crop plants (i.e., intraspecifc) is often considered independently of crop‐weed competition (i.e., interspecific), the mechanisms through which yields are reduced may be common to both. The objective of this study was to use the experimental structure of a critical time for weed removal study to examine the timing and effect of intraspecific competition on maize (Zea mays L.) biomass accumulation and phenological development. A field trial was conducted in which maize stands were thinned from a higher to a lower density at six stages of development. Results indicated that intraspecific competition at densities of 8 and 16 plants m−2 did not affect maize biomass accumulation until the 14th and 12th leaf tip stages, respectively. Before these stages, maize seedling growth at 8 or 16 plants m−2 was not resource limited. Increases in leaf area index and specific leaf area at the onset of intraspecific competition, and the recovery of plants following the removal of competitors, suggest that reductions in the rate of crop growth and development may have been linked to competition for light quantity.