MAXIMIZING GROWTH OF VEGETABLE SEEDLINGS IN CONTROLLED ENVIRONMENTS AT ELEVATED TEMPERATURE, LIGHT AND CO₂.

Seedlings of cucumber ‘Burpee Hybrid’, tomato ‘Michigan-Ohio’ and lettuce ‘Grand Rapids’ were germinated in the greenhouse for 5, 8, and 11 days respectively, and then grown for 15 days at elevated temperature (30/24° C), light (43.1 klx), and CO₂ (2,000 ppm) a 16-hr photoperiod, 65% relative humidity, and fertilized 4 times daily.
At the end of this time, they weighed 2 to 4.6 times those grown at standard environmental conditions in the growth chamber (24/18°C, 21.5 klx, and 400 ppm CO₂) and 10 to 25 times those of greenhouse controls kept on natural days (24/18°C, 350 ppm CO₂, and ca 12 -hr photoperiod).

Leaf expansion of seedlings grown under elevated growth chamber conditions was double that of seedlings in standard growth chamber conditions, and 6 to 7 times greater than under natural days in the greenhouse.

Temperature was the most limiting factor for seedling growth.
At the levels of light and CO₂ used in the experiment, CO₂ was more limiting than light intensity.
In general, optimum seedling growth was obtained when temperature, light, and CO₂ were increased simultaneously.

The most striking effects of CO₂ enrichment were precocious flower bud formation in tomato and cucumber and extensive growth of the lateral buds in all three species.

Symposium on Basic Problems of Protected Vegetable Production

D.T. Krizek, W.A. Bailey, H. Klueter, R.C. Liu

https://doi.org/10.17660/ActaHortic.1974.39.7