A research group at the University of Tokyo Graduate School, in collaboration with RIKEN, University of Tsukuba, Kisarazu National College of Technology, and Plants Laboratory, is using hydroponic cultivation in a plant factory to heat the culture solution by 3°C to increase the amount of nutrients from the roots. It was revealed that the uptake and amino acid metabolism were promoted, and the growth of hydroponic lettuce and functional components such as carotenoids and vitamin C were improved.
Although it is known that temperature has a large effect on photosynthesis and plant growth, there are many unknowns about the influence of the temperature of the hydroponic culture solution (rhizosphere temperature) on plant metabolism and growth. Previous research by the same group had found that raising the culture solution a few degrees Celsius above room temperature may improve plant growth and quality. Therefore, we investigated the effect of heating the culture solution at 3°C on the plant growth and functional components of lettuce grown at various room temperatures in an artificial light plant factory.
As a result, by heating the culture solution by 3°C under all room temperature conditions, aboveground dry weight and underground dry weight significantly increased. In addition, functional components such as chlorophyll, carotenoids, and ascorbic acid (vitamin C) were improved. Furthermore, soluble protein content and various minerals were also increased in both roots and leaves.
These results show that heating the culture solution to 3°C promotes the uptake of nutrients from the roots, and also increases the content of various amino acids in the roots, which activates root metabolism. It was found that the growth and functional components of hydroponic lettuce were improved.
The results of this research are expected to lead to the development of new cultivation methods that increase crop productivity and the production of functional ingredients. In the future, the company plans to establish a system that can maximize yield and quality with minimal input of resources and energy, and will proceed with technological development to minimize environmental impact.
Paper information:[Frontiers in Plant Science] Raising root zone temperature improves plant productivity and metabolites in hydroponic lettuce production
