Effects of early stress on plant-to-plant variability and grain yield in maize (Zea mays. L)
Early weed competition and high seeding densities are stresses that affect grain yield. The objectives of this study were to study the effect of early stresses on plant-to-plant variability and how this may affect grain yield. Field experiments were conducted in 2008 and 2009. Maize was exposed to different levels of early stress, created with intra- and inter-specific competition. Different levels of intra- and inter-specific competition where created with initial plant densities of maize and time of weed removal, respectively. Early stress decreased total dry matter per plant, increased plant-to-plant variability and reduced grain yield. Yield loss, however, was not attributed to an increase in plant-to-plant variability but rather to a decrease in intercepted photosynthetic active radiation. We hypothesize that an increase in plant-to-plant variability caused by early stress may reduce yield if stressful conditions occur during the critical period for kernel set.