1. “Climate control under artificial light” By André Kool, consultant Green Q 10 February 2010

2. HPS-lights+LED (Komeett, IC) TEKST

3. HPS-lights+LED (Komeett, IC)

4. LED-lights = growth pipe? TEKST

5. Curly leaves near LED  sugar accumulation? TEKST

6. Botrytis

7. Leaf tips in tomatoes  weak plant cell walls

8. Weak plant cell walls high humidity  less Ca in cell wall  weak  root pressure, (sudden) evaporation  cell wall burst

9. Weak plant cell walls

10. Botrytis hits damaged leafs……

11. …..and finally stem botrytis

12. Humidity rims in cucumber

15. Problems related to artificial light Artificial light  crops evaporates  Ca uptake by leaves Ca = required for strong cell walls Too high humidity  crop evoporates loo less  too less Ca in leaves  too less Ca in plant cell wall “Shocks” in humidity and /or root pressure  cell wall burst  leaf rims > X hours Y % air humidity = botrytis

16. Prevention / solution For uptake of Ca in leaves create evaporation during hours of lighting  HD >3 (3.0-6.0) Avoid extreme high greenhouse air humidities:  pre-night not <1.5, but certainly not < 1.0  after-night 1.5-2.5, preferably >2.0  morning 2.5-3.0  afternoon peak 3.0-5.0 (tomatoes 4.0-6.0)

17. Prevention / solution Create sufficient air movement en evaporation by: (Growth) pipe  > 20°C warmer than surrounding air. Careful ventilation during cold weather (frost) and lights on  no cold air falling down on heads  blocks evaporation  problems……… Try to ventilate with small % at lee-side even at (heavy) frost at artificial light and high greenhouse humidity  Feel if windows are not frozen to construction In Finland small ventilation % at -16°C (no wind). Small % (1-2%) is enough too get rid of humidity  more =risk of cold heads

18. Questions?

19. Thanks for your attention! www.greenq.nl