Impact of successive drought and re-watering cycles on growth and specific leaf area of two Populus x canadensis (Moench) clones, 'Dorskamp' and 'Luisa_Avanzo'

Abstract

Responses to successive drought and re-watering cycles (1-3 cycles) were compared in greenhouse-grown cuttings of Populus x canadensis (Moench) clones, 'Luisa_ Avanzo' and 'Dorskamp.' Total leaf number increment rate, duration of leaf expansion, total and individual leaf area expansion rates and stomatal conductance were recorded periodically during the experiment. Soil water content (SWC) and predawn leaf water potential (Psi(WP)) were measured four times during each drought cycle. In parallel, relative leaf water content (RWC) and specific leaf area (SLA) were estimated on leaves collected from the top to bottom of each cutting. Under well-watered conditions, 'Luisa_Avanzo' and 'Dorskamp' differed in their patterns of leaf area expansion. Although duration of leaf expansion was similar between clones, 'Luisa_ Avanzo' exhibited higher total leaf number increment rates and individual leaf area increases than 'Dorskamp.' As a result, 'Luisa_Avanzo' cuttings reached larger individual and total leaf areas than 'Dorskamp.' 'Dorskamp' leaves had lower SLA than 'Luisa_Avanzo' leaves. In response to successive drought cycles, both clones underwent decreases in total leaf number increment rates and in total leaf area expansion rates, but both whole-plant and individual leaf areas were drastically reduced only in 'Luisa_Avanzo.' 'Dorskamp' maintained a constant leaf area as a result of an increase in the duration of leaf expansion during drought and a significant stimulation of individual leaf area expansion rate and total leaf number increment rate in response to re-watering. Drought caused a greater decrease in SLA in 'Luisa_Avanzo' than in 'Dorskamp.' Expanded leaves of 'Dorskamp' were constitutively dense or thick, or both, whereas leaves of 'Luisa_Avanzo' became dense or thick, or both, only in response to drought. In both clones, re-watering caused partial recovery of SLA to control values. Our data confirm previous field and greenhouse observations that 'Dorskamp' is more tolerant to successive drought and re-watering cycles than 'Luisa_Avanzo.' We conclude that this difference is mainly attributable to the plasticity of 'Dorskamp' after re-watering, rather than to clonal differences in drought responses.

Interactive effects of elevated CO2 and drought stress on leaf water potential and growth in Caragana intermedia

“…Table 2 F-values of two-way ANOVA for tree height, basal diameter, number of leaves, leaf area, specific leaf area (SLA), leaf biomass, shoot biomass, root biomass, total biomass, leaf area ratio (LAR), root mass ratio (RMR), root:shoot ratio (RSR), and canopy productivity index (CPI) of C. intermedia seedlings measured at two CO 2 concentrations of 350 and 700 µmol mol −1 (CO 2 ) and three water regimes of well-watered, moderate-watered, and drought-stressed conditions (water) .5*** 13.1*** 11.8*** 0.4 NS 15.6*** 56.5*** 57.6*** 62.0*** 13.2*** 1.4 NS 0.5 NS 9.5** Water 2, 66 27.4*** 33.7*** 19.7*** 31.8*** 1.6 NS 37.5*** 40.1*** 20.3*** 45.2*** 1.7 NS 9.2*** 6.6** 4. Drought adapted tissue generally has lower SLA because of xeromorphic features such as thicker cuticles, mesophyll, and epidermal cells, or higher trichome density (Hsiao and Acevedo 1974;Turner and Kramer 1980;Kramer 1983;Fernández et al 2002;Marron et al 2003;Zhang et al 2004). No significant drought effects were observed in SLA at ambient CO 2 in this study.…”

Variability in Populus leaf anatomy and morphology in relation to canopy position, biomass production, and varietal taxon

“…The relevance of the use of leaf traits as determinants of biomass production as well as for taxonomic applications is therefore strongly dependent on the growth conditions of the concerned plant material. For instance, it has been shown that leaf area and leaf number increment are robust indicators of productivity under various environmental conditions, while the links between productivity and specific leaf area vary according to growth irradiance and temperature as well as with the age of the plants [41,[43][44][45]. Thus, the finding of stable determinants remains an open question, and only a few studies have examined the relevance of leaf anatomy and stomatal characteristics for this purpose.…”

Impact of drought and leaf development stage on enzymatic antioxidant system of twoPopulus deltoides×nigraclones

“…For similar limitation of water availability, growth of 'Dorskamp' was less affected than 'Luisa_Avanzo' one [11]. In response to re-watering, 'Dorskamp' only displayed the ability to recover a similar level of biomass production than well watered plants [11]. In this context, we have previously shown that non enzymatic antioxidant activity in leaves of the two clones decreased in response to water deficit, suggesting a limited participation of this class of molecules during drought [10].…”

“…For similar limitation of water availability, growth of 'Dorskamp' was less affected than 'Luisa_Avanzo' one [11]. In response to re-watering, 'Dorskamp' only displayed the ability to recover a similar level of biomass production than well watered plants [11].…”

“…However, their productivity is closely linked to water availability [21]. Even if poplars are among the most susceptible woody plants to drought, a large clonal variation in drought resistance within Populus species and hybrids has been described [10,11]. A large number of responses occurs in trees under drought conditions, thus it is difficult to determine the mechanisms that contribute to explain diversity in drought tolerance among poplar clones [21].…”