Abstract
It is generally postulated that at the tree scale a drought-related decrease in hydraulic conductance is balanced by a decrease of leaf area. We hypothesized that, at the individual leaf scale, drought affects the allometry between leaf area or mass and hydraulics, leading to a non-linear relationships between these traits. The study was conducted on well-watered and on water-stressed shoots of several apple genotypes covering an extended range of leaf area. Working on dried leaves, we measured leaf lamina area and mass and analyzed their relationships with the maximal xylem hydraulic conductance of the water pathway through the parent shoot and the petiole connected to the leaf lamina. Drought decreased leaf area and mass in absolute values. It also changes the allometric relationships between these two variables: for a same decrease of leaf dry mass the water-stressed shoot had a lower decrease of leaf dry area than the well-watered shoot. Our study also showed that drought affected the stem-to-petiole hydraulics with a higher hydraulic efficiency in the well-watered shoot compared to the water-stressed shoot. We discuss that, compared to the well-watered condition, drought not only decreased leaf size, but also reduced xylem efficiency through the stem-to-petiole pathway with regard to the leaf area and mass supplied.
Highlights
Water availability is one of the major limitations to plant productivity (Wood 2005)
The analysis of the relationships between stem-topetiole xylem conductance and final leaf area and mass across several apple genotypes showed that drought decreased leaf size and altered the allometric relations between these traits
Our study demonstrated that the water regime did not strongly affect the ranking of genotypes for leaf area and mass
Summary
Water availability is one of the major limitations to plant productivity (Wood 2005). We relied on KStem-Petiole as an easy-to-measure, integrated variable measuring the efficiency of water transport to the leaf lamina, with a good correlation between total petiole vessel cross-section area and hydraulic conductance of the petiole (Bucci et al 2003), which has been demonstrated at the stem level (Lauri et al 2011) Based on this assumption, our objective was to get a better understanding of how drought affects biomass allocation into the leaf, namely mass and area, which are among the basic traits of the leaf investment strategies (Wright et al 2004), in relation to the xylem water entering the leaf through the stem-to-petiole continuum. We discussed the effects of the water regime on these allometric relationships from the point of view of the variation of water transport efficiency through the stem-to-petiole continuum
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
