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“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 tomatoesweak plant cell walls Weak plant cell walls high humidity less Ca in cell wallweak root pressure, (sudden) evaporationcell wall burst Weak plant cell walls Botrytis hits damaged leafs…… …..and finally stem botrytis Humidity rims in cucumber Humidity rims in cucumber 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 humiditycrop evoporates loo lesstoo 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 (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) 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 evaporationproblems……… • 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! www.greenq.nl