Effects of population density and number of ears on wheat yield and its components

Abstract

Three field experiments were conducted to examine the effect of population density and number of ears on yield and its components in spring wheat. Two trials, carried out under intensive cultivation conditions in highly fertile soils, differed in plant distribution pattern, variety, and year. In both trials, there is a plateau of yield per unit area over a wide range of population densities. A third trial was conducted in a region marginal for wheat; here the maximum yield was obtained with a commercial plant density of 300 plants/m 2. Seeding rate had a major effect on the number of tillers and ears per m 2. Patterns of plant distribution appeared to affect number of ears, but not number of tillers; however, this result must be interpreted with caution due to possible varietal and seasonal effects. A high positive correlation was found between yield per m 2 and ears per m 2. It was concluded that under these conditions the number of ears per unit area is the dominant yield component. Negative correlations were obtained between most of the parameters affecting the yield per plant and the yield per unit area. Removing some of the ears in each plot caused an increase in the yield of the remaining ears. In all cases the yield increase per ear was not enough to compensate for the yield decrease per unit area resulting from ear thinning.