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This article in AJ

  1. Vol. 64 No. 4, p. 509-515
    Received: Nov 5, 1971



Effect of Day/Night Temperature on Factors Associated with Growth of Nicotiana tabacum L. in Controlled Environments1

  1. Mohammed Haroon,
  2. R. C. Long and
  3. J. A. Weybrew2



Growth of flue-cured tobacco (Nicotiana tabacum L.), ‘NC2326,’ was studied under controlled conditions in the North Carolina State University Phytotron (Southeastern Plant Environment Laboratory) to determine the patterns of growth over a wide range of day/night temperatures. Day temperatures ranged from 18 to 34 C at 4-C intervals; night temperatures ranged from 14 to 30 C at 4-C intervals. The growth of seedlings from first leaf to transplant size (Experiment I) was determined weekly intervals under all possible day/night temperature combinations. Fresh weight, dry weight, and leaf number were affected to a greater extent by night than by day temperature. The minimum night temperature for growth lies between 18 and 22 C. The 34/30 treatment yielded maximum fresh and dry weights, while maximum leaf number occurred under the 34/26 treatment. Diurnal variation in temperature favored increased growth. During early stages of seedling growth fresh and dry weight accumulation exhibited a bimodal response to day temperature.

The growth of plants from transplant size to appearance of the first flower (Experiment II) was studied under the following day/night temperatures: 34/30, 30/26, 26/22, 22/18, and 18/14. Whole-plant fresh and dry weights, leaf fresh and dry weights, leaf number, and plant height increased with temperature to 30/26, but decreased slightly at 34/30. Days.to.flower decreased with temperature to 26/22 and then increased at higher temperatures.

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