Physiological responses of carambola trees to soil water depletion

Rashid Al-Yahyai*, Bruce Schaffer, Frederick S. Davies

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Two-year-old 'Arkin' carambola (Averrhoa carambola L.) trees were grown in containers in a greenhouse and the field in a very gravelly loam soil. Trees in the field were subjected to four soil water depletion (SWD) levels which averaged, 10.5%, 26.5%, 41.0%, and 55.5% and trees in the greenhouse were maintained at field capacity or dried continuously to produce a range of SWD levels. The relationships between SWD and leaf (ΨL) and stem (ΨS) water potential, net CO2 assimilation (A CO2), stomatal conductance of water (gs) and transpiration (E) were determined. Coefficients of determination values between physiological variables were higher for trees in the greenhouse than in the field, which may have been due to greater fluctuations in vapor pressure deficit (VPD) in the field. Soil water depletion levels above 50% caused a reduction in ΨS that subsequently decreased gS. This reduction in ΨS was correlated with a linear reduction in E and a considerable decline in ACO2 when gS fell below about 50 mmol·m-2·s-1. Leaf gas exchange parameters were better correlated with ΨS than with SWD level. Therefore, ΨS may be a better predictor of carambola tree water status than SWD in a well-drained, very gravelly loam soil.

Original languageEnglish
Pages (from-to)2145-2150
Number of pages6
Issue number7
Publication statusPublished - Dec 2005
Externally publishedYes


  • Averrhoa carambola
  • Net carbon assimilation
  • Stomatal conductance
  • Water potential

ASJC Scopus subject areas

  • Horticulture


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