Effect of localized nitrogen availability to soybean half-root systems on photosynthate partitioning to roots and nodules

Journal Article · Sat Feb 28 23:00:00 EST 1987 · Plant Physiol.; (United States)

DOI:https://doi.org/10.1104/pp.83.3.552· OSTI ID:6549871

Singleton, P W; van Kessel, C

Soybean (Glycine max (L.) Merr. cv Davis) was grown in a split-root growth system designed to maintain control of the root atmosphere. Two experiments were conducted to examine how 80% Ar:20%, O/sup 2/ (Ar:O/sub 2/) and air (Air) atmospheres affected N assimilation (NH/sub 4/NO/sub 3/ and N/sub 2/ fixation) and the partitioning of photosynthate to roots and nodules. Application of NH/sub 4/NO/sub 3/ to nonnodulated half-root systems enhanced root growth and root respiration at the site of application. A second experiment applied Ar:O/sub 2/ or air to the two sides of nodulated soybean half-root systems for 11 days in the following combinations: (a) Air to both sides (Air/Air); (b) Air to one side, Ar:O/sub 2/ to the other (Air/Ar:O/sub 2/), and (c) Ar:O/sub 2/ to both sides (Ar:O/sub 2//Ar:O/sub 2/). Results indicated that dry matter and current photosynthate (/sup 14/C) were selectively partitioned to nodules and roots where N/sub 2/ was available. Both root and nodule growth on the Air side of Air/Ar:O/sub 2/ plants was significantly greater than the Ar:O/sub 2/ side. The relative partitioning of carbon and current photosynthate between roots and nodules on a half-root system was also affected by N/sub 2/ availability. The Ar:O/sub 2/ sides partitioned relatively more current photosynthate to roots (57%) than nodules (43%), while N/sub 2/-fixing root systems partitioned 36 and 64% of the carbon to roots and nodules, respectively. The Ar:O/sub 2/ atmosphere decreased root and nodule respiration by 80% and nitrogenase activity by 85% compared to half-root systems in Air while specific nitrogenase activity in Ar:O/sub 2/ was 50% of nodules supplied Air. Results indicated that nitrogen assimilation, whether from N/sub 2/ fixation or inorganic sources, had a localized effect on root development.

• Research Organization: Univ. of Hawaii, Paia
• OSTI ID: 6549871
• Journal Information: Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 83:3; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BACTERIA
BIOLOGICAL AVAILABILITY
CARBON 14 COMPOUNDS
CHEMICAL REACTIONS
GLYCINE HISPIDA
GROWTH
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LEGUMINOSAE
MICROORGANISMS
NITRATES
NITROGEN COMPOUNDS
NITROGEN FIXATION
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PLANT GROWTH
PLANTS
RHIZOBIUM
ROOTS
SYNTHESIS
TRACER TECHNIQUES