title: Effect of terminal locations of pods on biomass production and 13C partitioning in a fasciated stem soybean Shakujo.
abstract: This study addresses the hypothesis that stagnation of soybean yield on the farm can be improved by selection of a physiological trait favoring carbon assimilate partitioning to terminally placed pods versus genotypes having axillary pods at close plant spacing. (13)C was fed to source-sink units comprising a leaf, axillary/terminal pods, and petioles at upper and lower positions of the stem axis in two soybean cultivars, namely Shakujo and Enrei, at different densities of populations. The cultivars differ significantly in architecture, Shakujo bearing a few hundreds of pods in close succession to one another in a terminally placed raceme, in contrast to Enrei having axillary racemes. Pod yield per plant was higher in Enrei than in Shakujo at low density, but Shakujo out-yielded Enrei at close spacing. Population density decreased yield per plant and altered the pattern of assimilate partitioning significantly within the plants for both varieties. At high density more assimilates moved to the upper parts at the cost of the lower parts. The terminally placed pods of Shakujo were advantaged to receive assimilates under density stress. No benefit was accrued to pod filling of Enrei, however, under this condition.
authors.affiliation: Department of Environmental Dynamics and Management, Graduate School of Biosphere Sciences, Hiroshima University, Higashi-Hiroshima 739-0046, Japan.
authors.forename: Kyosuke
authors.initials: K
authors.lastname: Yamada
authors.forename: Aoi
authors.initials: A
authors.lastname: Sasakura
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Nishiwaki
authors.forename: Hany A
authors.initials: HA
authors.lastname: El-Shemy
authors.forename: Pravat K
authors.initials: PK
authors.lastname: Mohapatra
authors.forename: Nguyen T
authors.initials: NT
authors.lastname: Nguyen
authors.forename: Hideki
authors.initials: H
authors.lastname: Kurosaki
authors.forename: Syunsuke
authors.initials: S
authors.lastname: Kanai
authors.forename: Junki
authors.initials: J
authors.lastname: Ito
authors.forename: Kounosuke
authors.initials: K
authors.lastname: Fujita
mesh_terms: D018533:Biomass; D002245:Carbon Dioxide / Q000378:metabolism; D002247:Carbon Isotopes; D008954:Models, Biological; D010788:Photosynthesis; D018515:Plant Leaves / Q000378:metabolism; D018547:Plant Stems / Q000378:metabolism; D012639:Seeds / Q000254:growth & development / Q000378:metabolism; D013025:Glycine max / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D002247:Carbon Isotopes; D002245:Carbon Dioxide