title: Photoperiod effects on growth rate of in vitro cultured soybean embryos.
abstract: The growth rate of excised soybean (Glycine max [L.] Merrill) embryos grown in liquid culture increased linearly as photoperiod was increased from 0 to 20 h at an irradiance of 9 W m-2 measured between wavelengths of 700-850 nm from clear incandescent lamps.  When irradiance levels were varied between 0.1 and 1.7 W m-2, the maximum growth rates of embryos occurred at ca. 0.5 W m-2 at both 10- and 16-h photoperiods.  When the light source was changed from clear incandescent lamps, with a red (600-700 nm) to far-red (700-770 nm) ratio of ca. 1.07, to a BCJ incandescent lamp (Corning Glass dark red, transparent envelope and a red to far-red ratio of ca. 0.19), the growth rate of embryos slowed.  These results are consistent with a high irradiance response for growth of soybean embryos.
authors.affiliation: Department of Soil Science, North Carolina State University, Raleigh 27650, USA.
authors.forename: C D
authors.initials: CD
authors.lastname: Raper
authors.forename: R P
authors.initials: RP
authors.lastname: Patterson
authors.forename: M L
authors.initials: ML
authors.lastname: List
authors.forename: R L
authors.initials: RL
authors.lastname: Obendorf
authors.forename: R J
authors.initials: RJ
authors.lastname: Downs
mesh_terms: D007259:Infrared Rays; D008027:Light; D008029:Lighting; D017440:Photoperiod; D010788:Photosynthesis; D012639:Seeds / Q000254:growth & development* / Q000528:radiation effects; D013025:Glycine max / Q000254:growth & development* / Q000528:radiation effects