Stress responses of Salix gracilistyla and Salix subfragilis cuttings to repeated flooding and drought

Abstract

To compare the responses to repeated flooding and drought of Salix gracilistyla, which grows on coarse gravel substrates, and Salix subfragilis, which grows on fine silt or clay substrates, we measured pre-dawn leaf water potential (Ww pd ), osmotic adjustment (Ww tlp , Wo sat ), and biomass production of cuttings under greenhouse conditions. The experimental design involved a control and four treatments that crossed 1 or 3-week flooding (F) with 1 or 2-week droughts (D). Ww pd was reduced after 2 weeks of drought when preceded by 1 week of flooding. Neither species increased osmotic adjustment in response to increased duration of drought between repeated 3-week flooding. Moreover, a decrease in the ratio of leaf biomass to total biomass or an increase in the ratio of root biomass to total biomass with longer drought repetitions was not observed for either species. The root ratio of S. gracilistyla was more strongly inhibited by flooding than that of S. subfragilis. The shoot-to-root ratio of S. subfragilis was higher than that of S. gracilistyla in all F combinations. The hypertrophied lenticel ratio of S. gracilistyla after 1 week of flooding was nearly the same as that after 3 weeks of flooding, whereas values for S. subfragilis after 1 week of flooding were lower than those after 3 weeks of flooding. The low allocation to roots and the generation of hypertrophied lenticels by S. gracilistyla in response to flooding, as compared with S. subfragilis, seem to be related to the different habitat substrate conditions of the two species.

Functional responses to multiple sequential abiotic stress (waterlogging‐drought) in three woody taxa with different root systems and stress tolerance

“…Those authors observed a decrease in the root/shoot ratio as a consequence of prolonged (6 weeks) or cyclical waterlogging (2 weeks of flooding, 2 weeks watered to field capacity, 2 weeks of drought) due to a reduction of the root compartment. A similar root response as a consequence of repeated waterlogging was reported in S. alba(Markus- Michalczyk et al, 2016b) and in S. gracilistyla(Nakai & Kisanuki, 2011). In SmxSa, the observed lack of effects on RB-despite the shorter root length-could be explained, at least in part, by the higher root production rate (number of roots generated as a function of time) reported for this hybrid compared to "Barret 13-44 INTA" clone, either under Control or after waterlogging combined with salinity conditions(Quiñones Martorello et al, 2020).…”

Physiological responses to alternative flooding and drought stress episodes in two willow (Salixspp.) clones

“…In poplars, the occurrence of a pre-conditioning flooding period improved waterlogging tolerance (Bejaoui et al 2012). In willows, the combination of drought and flooding has been addressed to a lesser extent than both stresses separately (Nakai et al 2010, Nakai andKisanuki 2011). Some morphological responses to drought are the opposite of those to flooding.…”

Growth and Physiological Adaptation of Salix matsudana Koidz. to Periodic Submergence in the Hydro-Fluctuation Zone of the Three Gorges Dam Reservoir of China

“…Salix subfragilis L. was more tolerant to flooding than Salix gracilistyla Miq. due to higher root ratio under flooding [36]. Salix viminalis L., with a higher dry mass and greater resprouting capacity, had a higher tolerance to tidal flooding than Salix alba L. [37].…”

“…Frequent floods may increase tree mortality [65]. Reduced plant survival and growth in response to flooding is common among many species [30,36,66]. An investigation conducted in the TGDR found that S. matsudana and S. variegate were distributed in the water level fluctuation zone and they could endure 210 days of 5 m-deep submergence with a survival rate of 13% and 47%, respectively [62].…”