Inter-genotypic differences in drought tolerance of maritime pine are modified by elevated [CO2]. uri icon

abstract

  • Background and Aims Despite the importance of growth [CO2] and water availability for tree growth and survival, little information is available on how the interplay of these two factors can shape intraspecific patterns of functional variation in tree species, particularly for conifers. The main objective of the study was to test whether the range of realized drought tolerance within the species can be affected by elevated [CO2].
  • Conclusions Evidence from this study suggests elevated [CO2] can modify current ranges of drought tolerance within tree species.
  • Key Results eCO(2) had a neutral effect on the impact of drought on growth and leaf gas exchange of the most drought-sensitive genotypes while it aggravated the impact of drought on the most drought-tolerant genotypes at aCO(2). Thus, eCO(2) attenuated genotypic differences in drought tolerance as compared with those observed at aCO(2). Genotypic variation at both levels of growth [CO2] was found in specific leaf area and leaf nitrogen content but not in other physiological leaf traits such as intrinsic water use efficiency and leaf osmotic potential. eCO(2) increased Delta C-13 but had no significant effect on delta O-18. This effect did not interact with the impact of drought, which increased delta(18)Oand decreased Delta C-13. Nevertheless, correlations between Delta C-13 and delta O-18 indicated the non-stomatal component of water use efficiency in this species can be particularly sensitive to drought.
  • Methods Intraspecific variability in leaf gas exchange, growth rate and other leaf functional traits were studied in clones of maritime pine. A factorial experiment including water availability, growth [CO2] and four different genotypes was conducted in growth rooms. A 'water deficit' treatment was imposed by applying a cycle of progressive soil water depletion and recovery at two levels of growth [CO2]: 'ambient [CO2]' (aCO(2) 400 lmol mol(-1)) and 'elevated [CO2]' (eCO(2) 800 lmol mol(-1)).

publication date

  • 2017
  • 2017