Effect of Pretransplant Lighting on Post-transplant Growth and Development of Tobacco1
- M. J. Kasperbauer2
Uniformity in time of flowering is desirable in tobacco (Nicotiana tabacum L.) production, especially when mechanization is involved. This study was initiated to determine methods of controlling premature floral induction without causing undesirable side-effects to the plants. Burley tobacco seedlings were treated with various combinations of illumination during the pretransplant period in controlled-environment chambers and outdoors in modified starting beds. Effectiveness of control was assayed under field conditions.
Early floral induction occurred in seedlings that received high intensity short days and cool temperatures, or low intensity natural daylengths coupled with cool temperatures. When 12-minute middle-of-night interruptions were used, white fluorescent light was more effective than white incandescent light in counteracting a florally inductive environment, while incandescent was slightly more effective than fluorescent when 240-minute interruptions were used. Twelve minutes of white incandescent light applied in 30-second increments repeated each 10 minutes during a 240-minute period were almost as effective as 240 minutes of continuous illumination from the same type of lamps. Night interruptions with white and yellow incandescent light were equally effective. Phytochrome involvement in counteraction of floral induction in tobacco was discussed.
Pretransplant treatments that showed most promise in the controlled-environments were tested over outdoor starting beds in 1970 and 1971. The first year had a period of cool overcast weather during the treatment period, and the middle-of-night supplemental lighting was effective in delaying floral induction. Bright, warm days predominated during the 1971 treatment period, and no premature flowering occurred among either the controls or the treated plants. There were no undesirable side-effects of the supplemental lighting during either year.
In general, plants that flowered prematurely developed fewer leaves prior to flowering, produced several suckers per plant, were difficult to harvest, and yield of cured leaf was significantly reduced.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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