ISHS Acta Horticulturae 633: XXVI International Horticultural Congress: Protected Cultivation 2002: In Search of Structures, Systems and Plant Materials for Sustainable Greenhouse Production
CARBON STATUS OF CO2-ENRICHED TOMATO PLANTS UNDER COMMERCIAL GREENHOUSE CONDITIONS |
| Authors: | D.R. Edwards, P.A. Jolliffe, D.L. Ehret |
| Keywords: | Lycopersicon esculentum, leaf starch, specific leaf weight, assimilation, CO2 enrichment |
| Abstract:
Enriching greenhouses with supplemental CO2 has enabled tomato growers in British Columbia to exceed annual fruit yields of 70 kg m-2. CO2 sensors provide information on greenhouse concentrations, but do not assess CO2 fixation by the crop or plant carbon status. Our objective was to explore the status and dynamics of carbon pools, in particular leaf starch, diurnally and throughout the leaf canopy under commercial growing conditions. Two commercial greenhouses were sampled in the Lower Mainland of British Columbia, Canada during the 2001 growing season. Leaf samples were collected and analyzed for carbohydrate content. Starch content varied significantly through the canopy, declining from canopy top to bottom. This response was variable throughout the season, possibly reflective of climate variation and/or fruit load. Lower carbohydrate levels were observed in the morning and the evening, with higher levels at midday. In some cases, leaves carried over large amounts of carbohydrate overnight, implying that carbon supply exceeded capacity for carbon use. In some leaves, over 30% of the dry weight was starch, and correlations between leaf dry weight and starch were high (R>0.80). Leaf dry weight may possibly be an indicator of the carbohydrate status of the crop. Knowing this information would help optimize CO2 application by discontinuing or reducing enrichment when plants have adequate carbohydrate pools already warehoused in leaves. | |
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