Effects of CO2 concentration on photosynthesis, transpiration and production of greenhouse fruit vegetable crops

E.M. Nederhoff

Research output: Thesisexternal PhD, WU

Abstract

<p>The effect of the C0 <sub>2</sub> concentration of the greenhouse air (C) in the range 200 to 1100 μmol mol <sup>-1</SUP>was investigated in tomato ( <em>Lycopersicon esculentum</em> Mill.), cucumber ( <em>Cucumis sativus</em> L.), sweet pepper ( <em>Capsicum annuum</em> L.) and eggplant ( <em>Solanum melongena</em> L.), grown in greenhouses.<p>The effect of C on canopy net photosynthetic C0 <sub>2</sub> assimilation rate (or photosynthesis, P) was expressed by a set of regression equations, relating P to PAR, C and LAI. A rule of thumb ('CO <sub>2</sub> -rule') was derived, approximating the relative increase of P caused by additional C0 <sub>2</sub> at a certain C. This C0 <sub>2</sub> -rule is: X = (1000/C) <sup>2</SUP>* 1.5 (X in % per 100 μmol mol <sup>-1</SUP>, and C in μmol mol <sup>-1</SUP>). Two models for canopy photosynthesis were examined by comparing them with the experimental photosynthesis data. No 'midday depression' in P was observed.<p>The effects of C on leaf conductance ( <em>g</em> ) and on rate of crop transpiration ( <em>E</em> ) were investigated. An increase of 100 μmol mol <sup>-1</SUP>in C reduced <em>g</em> by about 3-4% in sweet pepper, tomato and cucumber and by about 11 % in eggplant. The effect of C on <em>E</em> was analyzed by combining the regression equation for g with the Penman-Monteith equation for <em>E</em> . C had only a relatively small effect on <em>E</em> , owing to thermal and hydrological feedback effects. The decoupling of <em>g</em> and <em>E</em> was quantified. No timedependent variation or 'midday depression' in <em>E</em> was observed, and no significant effect of C on average leaf temperature was established.<p>In five experiments, the effect of C on growth and production and on specific features were analyzed: light use efficiency was increased by about 10 to 15% per 100 μmol mol <sup>-1</SUP>increase in C; fruit set of sweet pepper was greatly increased by high C; allocation of biomass to fruits was increased by high C in sweet pepper and cucumber; specific leaf area (SLA) was reduced by 15 to 20% at 150 to 250 μmol mol <sup>-1</SUP>increase in C (except in cucumber); dry matter content (DMC) of vegetative organs slightly increased at high C (also not in cucumber); fruit production (dry weight) was most affected by C in sweet pepper; fresh weight fruit production per unit CO <sub>2</sub> was highest in cucumber; fruit quality was not influenced by C. High C promoted the 'short leaves syndrome' in tomato and 'leaf tip chlorosis' in eggplant, probably related to calcium and boron translocation, respectively. The observed effect of C on production was larger than expected on the basis of the CO <sub>2</sub> -rule. Intermittent CO <sub>2</sub> supply (ICS) could under normal ventilation accomplish only a limited increase in average C, and hence a limited increase in production. No physiological advantages of ICS were revealed.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
Supervisors/Advisors
  • Challa, H., Promotor
Award date25 Oct 1994
Place of PublicationS.l.
Publisher
Print ISBNs9789054853183
Publication statusPublished - 1994

Keywords

  • metabolism
  • plant nutrition
  • assimilation
  • photosynthesis
  • transpiration
  • evapotranspiration
  • carbon dioxide
  • fruit vegetables
  • vegetables
  • greenhouse horticulture

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