No-venting in greenhouse pushes tomato yield to 160kg per m2

At a conference in Italy some 25 years ago I presented a concept of the greenhouse of the future and suggested that tomato yields in excess of 1,500 t/ha/year might not be out of the question(150kg/m2).  There was shock and laughter at my suggestion.  I can now confirm that I was wrong—very wrong.  I badly underestimated what modern technology is capable of achieving.

In the 27 November 2024 Horti-daily was a short article on a Norwegian project which quotes tomato yields of 1600t/ha/year (160kg/m2).   My proposal. was to use a fully artificially lit plant factory, but the Norwegian project uses a modified (very modified) glasshouse.

The availability of cheap electricity (from hydropower) is the key to the system (could we not do that in New Zealand with geothermal power???)

This “optimum” environment for production was achieved in a fully closed greenhouse system by:

• the use of heat pumps to control the temperature.
• a dehumidifier to control humidity within the greenhouse. Note: the dehumidifier also provided fresh water for irrigation
• Supplementary LED lights to provide optimum light levels. Obviously very necessary during Norway’s winter months, and maybe something we should even consider in New Zealand, and
• CO₂ levels of 1200-1600 ppm obtained by extracting the CO₂ from the outside air.

The recent article in G2G by Stefan Vogrincic has stimulated this response, enhanced by a recent presentation during a NIAB (UK) webinar presentation on berry fruit, suggested that greenhouse strawberry plants are capable of producing yields of 2.5 kg/year/plant of grade 1 fruit (something in excess of 250t/ha/year (25kg/m2)).

This suggests that we still have a long way to go in establishing what the yield potential of horticultural crops might be!!!

The humble garden tomato – 2-4kg per m2?