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

HPS-lights+LED (Komeett, IC) TEKST

HPS-lights+LED (Komeett, IC)

LED-lights = growth pipe? TEKST

Curly leaves near LED  sugar accumulation? TEKST

Botrytis

Leaf tips in tomatoes  weak plant cell walls

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

Weak plant cell walls

Botrytis hits damaged leafs……

…..and finally stem botrytis

Humidity rims in cucumber

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

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

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

Questions?

Thanks for your attention!