Desk study: Is the use of interlighting in greenhouse production beneficial or wasteful?

In modern greenhouse production, plants are often grown in relatively tall, optically dense canopies –think of tomato, cucumber and bell pepper. Often, supplementary lighting installed above the plants (toplighting) is used to stimulate growth. The introduction of leds, which emit much less heat than traditionally used HPS lamps, has made it possible to place lamps closer to plants, enabling “interlighting”, a technique in which lights are placed in between plants as well as above them.

Theoretically, interlighting has many advantages: it delivers light to parts of the canopy that would otherwise be strongly shaded, thereby improving the distribution of light across the plant, theoretically improving light use efficiency, growth and yield. Also, it changes the acclimation state of leaves lower in the canopy (which changes their respiration and photosynthesis rates), and might even increase the formation of vitamins in the fruits growing close to interlights. Despite these theoretical benefits, few experimental reports have shown interlighting to actually be beneficial for yield, compared to toplighting, and in these reports the comparison between different treatments may not have been done correctly.

In this literature review and meta-analysis, you will compile published data on the effects of interlighting on whole-crop, leaf and fruit level, and will critically analyse these data, taking into account the correct basis of comparison. You will compare different experimental approaches, and may define a list of criteria for designing the ideal experiment(s) to determine the effects of interlighting in the future.

Used skills

  • Critical analysis of published experimental setups
  • Data collection
  • Data analysis

Interested in doing a BSc or MSc thesis at HPP? Please contact the HPP student coordinator Katharina Hanika.