Vessel scaling in evergreen angiosperm leaves conforms with Murray's law and area‐filling assumptions: implications for plant size, leaf size and cold tolerance

Abstract

Water transport in leaf vasculature is a fundamental process affecting plant growth, ecological interactions and ecosystem productivity, yet the architecture of leaf vascular networks is poorly understood. Although Murray's law and the West-Brown-Enquist (WBE) theories predict convergent scaling of conduit width and number, it is not known how conduit scaling is affected by habitat aridity or temperature. We measured the scaling of leaf size, conduit width and conduit number within the leaves of 36 evergreen Angiosperms spanning a large range in aridity and temperature in eastern Australia. Scaling of conduit width and number in midribs and 2° veins did not differ across species and habitats (P > 0.786), and did not differ from that predicted by Murray's law (P = 0.151). Leaf size was strongly correlated with the hydraulic radius of petiole conduits (r = 0.83, P < 0.001) and did not differ among habitats (P > 0.064), nor did the scaling exponent differ significantly from that predicted by hydraulic theory (P = 0.086). The maximum radius of conduits in petioles was positively correlated with the temperature of the coldest quarter (r = 0.67; P < 0.001), suggesting that habitat temperature restricts the occurrence of wide-conduit species in cold habitats.

Convergent xylem widening among organs across diverse woody seedlings

“…4). These findings are in agreement with previous studies focusing on adult plants (Waring et al, 1977;Coomes et al, 2008;Gleason et al, 2018;Petit et al, 2018). Natural selection endows plants with maximal transversal surface area per unit water volume (as in all exchange surfaces such as gills and blood capillaries); plants tend to maximize the number of the narrowest conduits in the terminus of the conductive system and ensure a constant conductance as the conductive stream grows longer, to retain their maximum photosynthetic productivity (West et al, 1999a,b;Sack et al, 2012).…”

“…The isometric scaling of conducting size with leaf size, together with the isometric scaling of leaf size with plant size (Cornelissen, 1999;Reich et al, 2006;Gleason et al, 2018), improves our overall understanding of the tip-to-base conduit widening, with regard to the similar scaling of xylem size of different organs with plant size (Fig. 3).…”

“…This tip-to-base widening of xylem tissue area enlightens our understanding of the whole-plant xylem conductance. Across different growing stages and individuals of diverse woody species, xylem conduits in each part (organ) should develop with a similar conductance-pace rule with plant height, as favored by natural selection (Olson, 2012;Gleason et al, 2018). That is, consistent scaling should be maintained, for , and between stem D max and total leaf area, for which RGR was not considered.…”

“…Regression coefficients of standardized major axis are documented in Table 1. instance, between the conduit D max of each part (organ) and plant size (distance to the apex) (Anfodillo et al, 2006;Holtta et al, 2013), between total (living) xylem area of leaves and stems according to the pipe model (Shinozaki et al, 1964), and between leaf D max and individual leaf area (Coomes et al, 2008;Gleason et al, 2018).…”

Plant Phenotypic Traits Eventually Shape Its Microbiota: A Common Garden Test

“…There are also other microbes related to these traits. Water transport in leaf vasculature is a fundamental process affecting plant and microbe growth, ecological interactions, and ecosystem productivity ( Gleason et al, 2018 ). The index, δ 13 C in leaf, is used to evaluate the water use efficiency of plants comprehensively.…”