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

Abstract

AbstractGrowth 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.