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This article in CS

  1. Vol. 25 No. 3, p. 533-537
    Received: Aug 17, 1984

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Responses of C4 Grasses to Atmospheric CO2 Enrichment. II. Effect of Water Stress1

  1. Nasser Sionit and
  2. David T. Patterson2



Changes in leaf water potential, photosynthesis, and stomatal conductance in response to atmospheric COs enrichment at two watering regimes were studied in :Four species of C4 grasses: Echinochloa crusgalli, Digitaria sanguinalis, Eleusine indica, and Setaria faberi. Plants were grown in controlled environment chambers at 350 and 675 μmol mol-1 CO2 with 1000 μmol m-2 s-1 photosynthetic photon tux density (PPFD). One group plants of each of the COs concentrations was subjected to water stress by withholding irrigation for 10 days starting 21 days after planting. Water potentials of the leaves of plants grown at 350 #tool mol-1 CO2 declined more rapidly and reached lower values at the end of the stress period than the water potential of those grown at 675 μmol mol-1 CO2. High COs-grown plants maintained higher turgor pressures than low CO2-grown plants. All plants had lower rates of photosynthesis during water stress compared to non-stressed conditions. However, the net photosynthetic rates of the plants grown at high CO2 concentration did not decline as rapidly as the rates of plants grown at low CO2 when subjected to water stress. The maintenance of turgor along with CO2 enrichment during water stress development in plant leaves may be responsible for the higher rates of net photosynthesis observed in high CO2-grown plants compared to those in low CO2-grown plants.

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