ISHS Acta Horticulturae 361: International Symposium on New Cultivation Systems in Greenhouse
EFFECT OF HIGH-PRESSURE MIST AND DAYTIME CONTINUOUS CO2 ENRICHMENT ON LEAF DIFFUSIVE CONDUCTANCE, CO2 FIXATION AND PRODUCTION OF ROSA HYBRIDA PLANTS GROWN ON ROCKWOOL |
| Author: | L. Urban |
| Abstract:
Rose plants (Rosa hybrida cultivar 'Sonia') were grown on rockwool in three plastic greenhouses: the first one was used as a control greenhouse, the second one had a relative humidity (RH) level of 75 to 100 % provided by high-pressure mist (HPM), and in the third greenhouse, HPM was associated with daytime continuous CO2 enrichment (HPM+CO2). CO2 was injected from 09.00 to 16.00. The daytime CO2 concentration was kept at around 900±100 ppm. CO2 injection could be maintained with reasonably low gas waste by limiting aperture rates of openings to less than 5 %. HPM was used to reduce air temperatures by evaporative cooling. Plants were irrigated at rates proportional to incident radiation. The effect of HPM and HPM+CO2 was investigated from mid-summer to fall, under natural conditions. These were characterized by high incident photosynthetic photon flux density, high temperature and low RH. HPM+CO2 helped to substantially improve net photosynthesis when compared to the control or to the HPM treatment. Leaf diffusive conductance and leaf water potential remained unaffected by HPM+CO2, when compared to HPM. HPM+CO2 improved the growth, measured as an increase in dry matter, the number of bud breaks and the number of marketable flowers m-2 by 57 %, 23 % and 19 %, respectively. Moreover, HPM+CO2 improved stem diameter, this may indicate that long-term benefits can be expected from this technique. As a conclusion, it appears that combining daytime continuous CO2 enrichment with HPM offers very good opportunities for improving greenhouse rose production even during summer in hot climate conditions. | |
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