Measurement of phloem transport rates by an indicator-dilution technique. [Triticum aestivum L]

Journal Article · Mon Oct 01 04:00:00 EDT 1990 · Plant Physiology; (USA)

DOI:https://doi.org/10.1104/pp.94.2.455· OSTI ID:5915107

Fisher, D B ^[1]

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1. Washington State Univ., Pullman (USA)

An indicator-dilution technique for the measurement of flow rates, commonly used by animal physiologists for circulation measurements, was adapted to the measurement of phloem translocation rates in the wheat (Triticum aestivum L.) peduncle. The approach is based on the observation that, during the transport of a given amount of solute, its mean concentration will be inversely proportional to flow rate. For phloem transport in the wheat peduncle, the necessary measurements are (a) the time course of tracer kinetics in the peduncle phloem, (b)the volume of sieve tubes and companion cells in the monitored segment of the peduncle, and (c) the amount of tracer transported past that point. The method was evaluated by in situ monitoring of {sup 32}PO{sub 4} transport in pulse-labeling experiments. Specific activities (i.e. {sup 32}P concentrations) of phloem exudate were in good agreement with those calculated from in situ count rates and measured phloem areas. Mass transport rates, calculated from volume flow rates and phloem exudate dry matter content, also agreed well with expected mass transport rates based on measurements of grain growth rate and net CO{sub 2} exchange by the ear. The indicator-dilution technique appears to offer good precision and accuracy for short-term measurements of phloem transport rates in the wheat peduncle and should be useful for other systems as well.

• OSTI ID: 5915107
• Journal Information: Plant Physiology; (USA), Journal Name: Plant Physiology; (USA) Vol. 94:2; ISSN 0032-0889; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ACCURACY
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BODY
CEREALS
DAYS LIVING RADIOISOTOPES
FLOW RATE
GRASS
ISOTOPE APPLICATIONS
ISOTOPE DILUTION
ISOTOPES
LIGHT NUCLEI
LILIOPSIDA
MAGNOLIOPHYTA
MATERIALS
MEASURING METHODS
NUCLEI
ODD-ODD NUCLEI
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORUS 32
PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
PHYSIOLOGY
PLANT SAP
PLANT TISSUES
PLANTS
RADIOISOTOPES
TISSUES
TRACER TECHNIQUES
TRANSLOCATION
WHEAT