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Crop Science Abstract -

Growth of Sugarbeet Seedling in Various Atmospheres of Oxygen and Carbon Dioxide1


This article in CS

  1. Vol. 20 No. 4, p. 456-458
    Received: Sept 21, 1979

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  1. Roger Wyse2



The allocation of photosynthates is the result of complex competitive interactions between sinks for available photosynthate. The objective of this research was to determine if altered photosynthate supplies would change the normal partitioning patterns in young sugarbeet plants. Photosynthetic rates were enhanced by CO2 enrichment and photorespiration was reduced by a combination of high CO2 and low O2. The plants were grown in growth chambers having day-night temperatures of 28/22 C with a photoperiod of 16 hours. When the first true leaves appeared, the seedlings were placed in treatment chambers within the larger growth chambers, and the following combinations of oxygen and carbon dioxide were established (% O2 — ppm CO2): 21-300; 21-1,000; 5-300; 5-1,000. Photon Flux Density within the treatment chambers was 320 /μE/m2/sec. The plants were maintained within the chambers for 10 days.

Elevated CO2 enhanced total dry matter accumulation by 180% but low O2 had no significant effect. The final dry matter accumulation expressed on a final leaf area basis was increased 56 and 19% by 1,000 ppm CO2 and 5% O2 respectively. The additional photosynthate resulting from enhanced photosynthesis was allocated preferentially to the root sink. The primary effect of low O2 was to enhance root diameter and leaf number, but low O2 had little effect on other growth characteristics. Results indicate that the young sugarbeet root is the preferred sink for additional photosynthate.

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