Correlation of genotype performance for agronomic and physiological traits in space-planted versus densely seeded conditions

Wheat breeding programs often have a generation of intense selection among space-planted individuals. An ultimate goal is always high yield potential of genotypes when transferred to densely seeded conditions. The goal of this experiment was to identify traits that may be selected in spaced-plants that are correlated with high yield potential under densely seeded conditions. We tested 20 spring wheat (Triticum aestivum L.) genotypes under three planting densities over a 2-yr period under both irrigated and nonirrigated conditions. Several traits were correlated with yield potential within seeding densities, including flag leaf width, grain fill period, and days needed to reach Haun growth stage 5. Additionally, genotype performance in spaced-planted versus densely seeded conditions was highly correlated for many of the measured traits. In particular, genotype performance for grain yield was significantly correlated between the planting densities (r = 0.83). Additionally, flag leaf width and development at Haun growth stage 5 were highly correlated between planting densities on the basis of mean performance over all four environments. These traits were also highly correlated when comparing individual space-planted environments to the mean genotype performance in the densely seeded environments. Genotype performance for grain fill period was highly correlated between planting densities on the basis of means of all four environments (r = 0.87). These correlations were lower, though generally significant, when each of the four space-planted environments was considered independently. In general, data from this study suggest that selection among space-planted genotypes for wide flag leaf, rapid growth to Haun stage 5, and long grain fill period may result in increased yield potential in densely seeded conditions.