Rapid hydraulic recovery in Eucalyptus pauciflora after drought: linkages between stem hydraulics and leaf gas exchange

Abstract

In woody plants, photosynthetic capacity is closely linked to rates at which the plant hydraulic system can supply water to the leaf surface. Drought-induced embolism can cause sharp declines in xylem hydraulic conductivity that coincide with stomatal closure and reduced photosynthesis. Recovery of photosynthetic capacity after drought is dependent on restored xylem function, although few data exist to elucidate this coordination. We examined the dynamics of leaf gas exchange and xylem function in Eucalyptus pauciflora seedlings exposed to a cycle of severe water stress and recovery after re-watering. Stomatal closure and leaf turgor loss occurred at water potentials that delayed the extensive spread of embolism through the stem xylem. Stem hydraulic conductance recovered to control levels within 6 h after re-watering despite a severe drought treatment, suggesting an active mechanism embolism repair. However, stomatal conductance did not recover after 10 d of re-watering, effecting tighter control of transpiration post drought. The dynamics of recovery suggest that a combination of hydraulic and non-hydraulic factors influenced stomatal behaviour post drought.

Down-Regulation of Plasma Intrinsic Protein1 Aquaporin in Poplar Trees Is Detrimental to Recovery from Embolism

“…7). This pattern of PLC recovery but delayed g s recovery from drought is a common phenomenon and has been observed in Eucalyptus pauciflora; stem hydraulic capacity was restored within 6 h, but stomatal conductance had not fully recovered even 10 d after a return to favorable water status (Martorell et al, 2013). Similar results were reported for grapevines; xylem embolism in petioles, roots, and shoots recovered during the 24 h after rehydration, whereas stomatal conductance required an additional 48 h .…”

Xylem embolism refilling and resilience against drought‐induced mortality in woody plants: processes and trade‐offs

“…Much research has investigated how plants avoid hydraulic failure by preventing formation and spread of catastrophic xylem embolism (Brodribb and Cochard 2009;Pittermann et al 2013). However, recent research suggests the existence of a spectrum of strategies ranging from 'resistance' to 'recovery', with some plants coming remarkably close to hydraulic failure, but recovering once xylem tension is partially or fully relaxed (Ogasa et al 2013;Martorell et al 2014). Indeed, many woody plants commonly operate at xylem pressures close to critical thresholds for runaway embolism (i.e.…”

“…Although still implicit and invasive to a certain degree, hydraulic conductivity measures directly the consequence of embolism, and the technique has been the basis for early descriptions of the Table 1 Study cases on xylem refilling published since 2013, divided by biome and woody plant species. Source references are: (1) Leng et al (2013); (2) Zwieniecki et al (2013); (3) Ooeda et al (2016); (4) Ogasa et al (2013); (5) Umebayashi et al (2016); (6) Martorell et al (2014); (7) Christman et al (2012); (8) Choat et al (2015); (9) Laur and Hacke (2014); (10) Mayr et al (2014); (11) Christensen-Dalsgaard et al (2014); (12) Rolland et al (2015); (13) Ganthaler and Mayr (2015); (14) Trifilo et al (2015); (15) Savi et al (2016); (16) Klein et al 2016;(17) Li et al (2016); (18) Numbers in parentheses indicate the reference number of the respective study in the reference list. The observed changes in embolism level for each species are in Fig.…”

Wood Anatomy and Plant Hydraulics in a Changing Climate

“…These patterns have led to the suggestion that angiosperm trees operate perilously close to their limits for catastrophic hydraulic failure and are at a high risk of mortality during drought events (Choat et al 2012). However, accumulating evidence points to a robust capacity of many angiosperms to regain stem hydraulic capacity following large drought-induced losses (Martorell et al 2014;Ogasa et al 2013;Urli et al 2013). In contrast, conifers are reputed to have a low ability to recover from massive embolism, consistent with their maintenance of larger safety margins (Brodribb et al 2010;Brodribb and Cochard 2009).…”