Root tissue structure is linked to ecological strategies of grasses

Abstract

The present study investigated to what extent there is a link between root tissue structure and ecological strategies of plant species ; such a link is known for leaf tissue structure. We investigated experimentally root tissue mass density, root diameter and several characteristics of root anatomy in the axile roots of 19 perennial grass species from different habitats and related these parameters to the ecological behaviour of the species. Root characteristics were assessed in new roots produced by mature plants grown under standardized conditions. The ecological behaviour was characterized in terms of relative growth rate (RGR), plant height at maturity and ecological indicator values for nutrients, light and tolerance to mowing according to Ellenberg. We found a striking dichotomy between root anatomical characteristics associated with interspecific variation in RGR and those associated with variation in plant height. RGR correlated with anatomical characteristics that contribute to root robustness, whereas plant height correlated with characteristics associated with axile root hydraulic conductance. RGR correlated negatively with tissue mass density (TMD r ) in roots. Interspecific variation in TMD r was explained by the proportion of stele in the cross-sectional area (CSA) of the axile root and the proportion of cell wall in the CSA of the stele. For a given root diameter, slow growing species had smaller, albeit more numerous, xylem vessels, indicating a higher resistance to cavitation and protection against embolisms. Plant height correlated positively with root CSA, total xylem CSA and mean xylem vessel CSA, indicating a need for a high transport capacity in roots of species that attain a large size at maturity. TMD r correlated positively with dry matter content in leaves. The results emphasize the close relationship between tissue structure and growth characteristics at the whole-plant level.

Morpho-anatomical characterization of root in recurrent selection cycles for flood tolerance of maize (Zea mays L.)

“…However, the ability of roots in absorbing water is affected by the lack of oxygen in flooded environments (Dell'Amico et al 2001, Tournaire-Roux et al 2003. Similar results on the characteristics of xylem vessels were reported in grasses (Wahl et al 2000).…”

A comparative study on plant growth and root plasticity responses of two Brachiaria forage grasses grown in nutrient solution at low and high phosphorus supply

“…A slower growth rate together with higher tissue mass densities are also typical for plants from less productive environments (Poorter and De Jong 1999) and our results confirm higher LMD and SMD for signalgrass. High LMD has been associated with high leaf C concentrations and a high investment in sclerenchyma and cell wall materials in grasses, traits that promote leaf longevity (Poorter et al 1995;Wahl and Ryser 2000). Greater LMD might confer longer term ecological benefits for signalgrass such as lower tissue turnover, reduced nutrient requirements and increased resistance to environmental hazards (Ryser and Lambers 1995;Ryser 1996;Vazquez de Aldana and Berendse 1997).…”

Changes in Community-Level Riparian Plant Traits over Inundation Gradients, Colorado River, Grand Canyon

“…Plants with dense wood may be more resistant to xylem cavitation, thus are well adapted to drought compared to species with porous, low density wood (Pockman and Sperry 2000;Hacke et al 2001;Chave et al 2009). Our study extends the use of SSG beyond woody plants to herbaceous plants, in which cavitation resistance also has been associated with stem tissue density (Wahl and Ryer 2000;Lens et al 2016). Also, we investigated plot coverage by species with the C4 photosynthetic pathway, which are mostly grasses in our study, because the C4 pathway confers greater photosynthetic rate and water use efficiency in semiarid areas with high irradiance and mean temperature (Doliner and Jolliffe 1979;Teeri and Stowe 1976;Kemp 1983).…”