Objective  Effects of exposure to red and/or blue LEDs in a cultivation facility on growth and photosynthesis of cherry tomato plants were studied.

  Method  Starting at 3-leaves-1-shoot stage, the Millennium Tomato seedlings were exposed to white light (CK), LEDred:blue=1 ∶ 1, LEDred:blue=7 ∶ 3, LEDred:blue=3 ∶ 7, red LED and blue LED for 30 days. During the treatment, changes on the dry and fresh weight gains, growth, and root/shoot ratio of the seedlings as well as the photosynthetic pigment contents, chlorophyll fluorescence parameters, peroxidase (POD) activity, superoxide dismutase (SOD) activity, and malondialdehyde (MDA) in the leaves were monitored.

  Result  The fresh weight of the tomato plants exposed to the LED treatments was higher than that of CK with the greatest effect found under 7red ∶ 3blue, which was 50.5% higher than that of CK, and the second highest of 31.3% increase over CK under 1red:1blue. On a dry weight basis, however, the greatest increase of 61.0% over CK was observed under 1red ∶ 1blue, which also rendered a significantly higher plant growth index than CK and the other treatments. Almost all the LED treatments increased the contents of chlorophyll a and chlorophyll b, except for red LED, which inhibited chlorophyll generation. POD became more active under increasing red exposure but less with increasing blue proportion when red and blue LEDs were combined for the treatment. No significant differences in the SOD activity of the plants exposed to different LED treatments was observed. The exposure to 1red ∶ 1blue produced the most MDA in leaves while red LED the least.

  Conclusion  The 1red ∶ 1blue LED combination yielded strong growth, high dry matter accumulation, and improved photosynthetic efficiency on the cherry tomato plants cultivated under a controlled environment as shown in the experimentation.