Effects of Low Intensity Light Quality on Photosynthesis and Nitrogen Assimilation of Young Tea Plants

Abstract

We examined the possibility of using of light emitting diodes (LEDs) as a covering cul- ture to improve tea leaf quality. We investigated the effects of red, blue, and white LED irradiation at 100 μmol m-2 s-1 PPFD on the growth, photomorphogenesis, photosynthesis, and nitrogen assimilation of young tea plants grown in hydroponic culture. After 15 days of light treatment, we saw increases in stomatal conductance, photosynthetic rates, transpi- ration rates, and soluble sugar content of new leaves in plants given a blue or white LED treatment, compared to the red LED treatment. No difference was seen in the increments in fresh weight of new leaves among the three LED treatments. Glutamine synthetase ac- tivities in rootlets were lower in plants in the red LED treatment than in the other two LED treatments. The rate of nitrogen translocation to new leaves was also the lowest in the red LED treatment. These findings suggested that irradiation with light containing blue wavelengths may be effective at improving the quality of tea plants, although no difference was seen in increments of fresh weight of new leaves in response to light quality under low light intensity.