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Abstract
Prior to reproductive development, the rate of leaf appearance is relatively uniform for the main-stems of soybean genotypes evaluated under unstressed field experiments. A recent discovery of a soybean breeding line with faster leaf appearance demonstrates the existence of phenotypic variation for this trait, which is supported by recent functional genomics studies that have identified a number of genes that regulate the rate of leaf appearance in other plant species. Subsequent characterization revealed that the genotype with faster node appearance requires approximately 0.5 fewer days to produce a new node on the main-stem under irrigated field conditions. Soybean yield potential is theoretically dependent upon the generation of nodes as a source of additional flowers and leaf biomass that support seed production. An increased rate of node accrual could benefit yield potential through earlier canopy closure, greater seasonal light interception, and increased harvest index. Overall, characterization of the faster node accrual trait will help to improve understanding of the molecular mechanisms controlling the rate of leaf appearance and to evaluate the importance of node production as it pertains to the development of elite, high-yielding soybean cultivars.
