Summary
The gas exchange characteristics of photosynthetic tissues of leaves and stems of Eriogonum inflatum are described. Inflated stems were found to contain extraordinarily high internal CO2 concentrations (to 14000 μbar), but fixation of this internal CO2 was 6–10 times slower than fixation of atmospheric CO2 by these stems. Although the pool of CO2 is a trivial source of CO2 for stem photosynthesis, it may result in higher water-use efficiency of stem tissues. Leaf and stem photosynthetic activities were compared by means of CO2 fixation in CO2 response curves, light and temperature response curves in IRGA systems, and by means of O2 exchange at CO2 saturation in a leaf disc O2 electrode system. On an area basis leaves contain about twice the chlorophyll and nitrogen as stems, and are capable of up to 4-times the absolute CO2 and O2 exchange rates. However, the stem shape is such that lighting of the shaded side leads to a substantial increase in overall stem photosynthesis on a projected area basis, to about half the leaf rate in air. Stem conductance is lower than leaf conductance under most conditions and is less sensitive to high temperature or high VPD. Under most conditions, the ratio C i /C a is lower in stems than in leaves and stems show greater water-use efficiency (higher ratio assimilation/transpiration) as a function of VPD. This potential advantage of stem photosynthesis in a water limited environment may be offset by the higher VPD conditions in the hotter, drier part of the year when stems are active after leaves have senesced. Stem and leaf photosynthesis were similarly affected by decreasing plant water potential.
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References
Adams MS, Strain BR (1968) Photosynthesis in stems and leaves of Cercidium floridum: spring and summer diurnal field response and relation to temperature. Oecol Plant 3:285–297
Adams MS, Strain BR (1969) Seasonal photosynthetic rates in stems of Cercidium floridum Benth. Photosynthetica 3:55–62
Adams WW III, Nishida K, Osmond CB (1986) Quantum yields of CAM plants measured by photosynthetic O2 exchange. Plant Physiol 81:297–300
Anderson DA, Szarek SR (1981) Ecophysiological studies on Sonoran Desert plants, VI. Seasonal photosynthesis and production of Machaeranthera gracilis, a winter ephemeral. Plant Cell Env 4:243–250
Atkins CA, Pate JS (1977) An IRGA technique to measure CO2 content of small volumes of gas from the internal atmosphere of plant organs. Photosynthetica 11:214–216
Billings WD, Godfrey PJ (1967) Photosynthetic utilization of internal CO2 in hollow stemmed plants. Science 158:121–123
Björkman O, Demmig B (1987) A survey of photon yield of O2 evolution and chlorophyll 77K fluorescence among vascular plants of diverse origin. Planta (in press)
Bornemisza-Pauspertl P, Sági F, Langer G, Schlenk B, Mózsik L (1984) Studies on the internal gas composition of the wheat stalk. Wiss Humboldt-Universität Berlin, Math-Nat. R 33:302–306
Delieu T, Walker DA (1981) Polarographic measurement of photosynthetic oxygen evolution by leaf discs. New Phytol 89:165–178
Farquhar GD, O'Leary MH, Berry JA (1982) On the relationship between carbon isotope discrimination and the intercellular carbon dioxide concentration in leaves. Aust J Plant Physiol 9:121–137
Keeley JE, Osmond CB Raven JA (1984) Stylites, a vascular land plant without stomata absorbs CO2 via its roots. Nature 310:694–695
McGinnies WG, Arnold JF (1939) Relative water requirement of Arizona range plants. Ariz Agric Exp Stn Tech Bull 80:165–246
Mulroy TW, Rundel PW (1977) Annual plants: adaptations to desert environments. BioScience 27:109–114
Price PW (1982) Wild buckwheat, Eriogonum inflatum (Polygonaceae): an enigmatic plant. Southwest Nat 27:147–253
Reveal JL, Munz PA (1968) Eriogonum. In: Munz PA, Suppl Calif Flora. Univ Calif Press, Berkeley, pp 33–72
Sharkey TD (1985) O2-insensitive photosynthesis in C3 plants. Its occurrence and a possible explanation. Plant Physiol 78:71–75
Smith SD, Osmond CB (1987) Stem photosynthesis in a desert ephemeral, Eriogonum inflatum. Morphology, stomatal conductance and water-use efficiency in field populations. Oecologia (Berlin) 72:533–541
Szarek SR, Woodhouse RM (1978) Ecophysiological studies of Sonoran Desert plants. IV. Seasonal photosynthetic capacities of Acacia greggii and Cercidium microphyllum. Oecologia 37:221–229
Vernon LP (1960) Spectrophotometric determination of chlorophylls and phaeophytins in plant extracts Anal Chem 32:1144–1150
von Caemmerer S, Farquhar GD (1981) Some relationships between the biochemistry of photosynthesis and the gas exchange of leaves. Planta 153:376–387
Walker DA, Osmond CB (1986) Measurements of photosynthesis in vivo with a leaf disc electrode: correlations between light dependence of steady state photosynthetic O2 evolution and chlorophyll a fluorescence transients. Proc R Soc Lond B Biol Sci 227:267–280
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Osmond, C.B., Smith, S.D., Gui-Ying, B. et al. Stem photosynthesis in a desert ephemeral, Eriogonum inflatum . Oecologia 72, 542–549 (1987). https://doi.org/10.1007/BF00378980
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DOI: https://doi.org/10.1007/BF00378980