Drought responses of Eucalyptus microtheca provenances depend on seasonality of rainfall in their place of origin

Abstract

We exposed seedlings of 12 Eucalyptus microtheca F. Muell. provenances to well-watered and waterstressed growing conditions in a greenhouse experiment and investigated the effects of drought on various plant properties in the provenances. We found significant variation in total biomass, height, root mass/foliage area ratio, foliage area/stem cross sectional area ratio, specific leaf area (SLA), water-use efficiency (WUE) and carbon isotope composition (δ 13 C) among the provenances. The observed inter-provenance variation was more pronounced in the water-stressed treatment than in the well-watered one. Drought increased root mass/foliage area ratio, foliage area/stem cross sectional area ratio, WUE, δ 13 C and decreased total biomass, height, transpiration and SLA. We also analysed relationships between plant properties and climate of native habitats of the provenances and found that most properties were strongly correlated with mean driest quarter rainfall. The correlation was positive for total biomass, height, transpiration and SLA and negative for root mass/foliage area ratio, foliage area/stem cross sectional area ratio, WUE and δ 13 C. Finally, we evaluated the intra-specific variation in foliage area/stem cross sectional area ratio in the context of tree hydraulic architecture: provenances from dry areas and trees grown under drought stress had more foliage per stem area ratio. However, their transpiration and the length of their hydraulic pathway were smaller and therefore the root to leaf water potential gradient might be smaller in these trees.

Interactions between drought and shade on growth and physiological traits in two Populus cathayana populations

“…These results revealed significant interaction effects of population with environmental factors (such as water, habitat, light, UV-B, and altitude) in plants, such as Eucalyptus microtheca F. Muell., Picea asperata Mast., and Hippophae rhamnoides L. in many previous studies (Li et al 2000;Duan et al 2005;Yang et al 2005). Our results confirmed that there is a close relationship among populations, watering regimes, and light regimes, and these factors act together to regulate physiological processes, which result in morphological and physiological differences between the populations.…”

“…The 13 C in combusted samples was measured with a mass spectrometer (Finnegan MAT Delta-E) as described by Li et al (2000). The overall precision of the values was better than 0.1%, as determined from repeated samples.…”

Climate-related variability in carbon and oxygen stable isotopes among populations of Aleppo pine grown in common-garden tests

“…Consistency of population performance for WUE i was estimated using Spearman rank correlations of different relationships involving d 13 C and d 18 O within and across sites. We also performed path analyses (Li 1975) to quantify the relative contributions of direct and indirect effects of climate variables on stable isotopes and height. A path analysis determines simple correlations between independent factors (in this case, climate T maxan mean annual maximum temperature, T minan mean annual minimum temperature, P an annual precipitation, P s summer precipitation, P s /P an ratio of summer to annual precipitation, PET an annual potential evapotranspiration, P an /PET an ratio of annual precipitation to annual potential evapotranspiration, VPD an mean annual vapour pressure deficit variables), and regresses all independent factors on each dependent factor (d 13 C, d 18 O or height) to obtain direct effects in the form of partial regression coefficients (i.e.…”

“…rainfall seasonality) are also important selective factors for water-use efficiency in Aleppo pine. Thus, a conservative water-use would be typical of drought-adapted populations from dry areas exposed to prolonged water stress periods in summer (Li et al 2000;this work). In contrast, populations with a less efficient water-use and, probably, more rapid consumption of available water would be adapted to more humid sites having a short, mild summer drought (Sandquist and Ehleringer 2003).…”

Genotypic variation in drought response of silver birch (Betula pendula Roth): leaf and root morphology and carbon partitioning

“…Plants that are able to make broad physiological adjustments to different environments will be able to survive and reproduce successfully across this range of environments (Bell and Lechowicz 1994). Provenance differences in drought sensitivity of tree species have been studied for (Tognetti et al 1995;García-Plazaola and Becerril 2000), earlysuccessional Pinus sylvestris (Palmroth et al 1999), and different species of Eucalyptus (Tuomela 1997;Li 1998;Li et al 2000;Pita and Pardos 2001). However, the reliance of most studies on plants grown from seeds rather than using clonal plants makes the separation of genetic variability and phenotypic plasticity difficult.…”