Stress responses of <Emphasis Type="Italic">Salix gracilistyla</Emphasis> and <Emphasis Type="Italic">Salix subfragilis</Emphasis> cuttings to repeated flooding and drought |
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| Authors: | Arisa Nakai Hiromitsu Kisanuki |
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| Institution: | (1) Graduate School of Bioresources, Mie University, 1577 Kurimamachiya, Tsu 514-8507, Japan |
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| 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 (Ψw
pd), osmotic adjustment (Ψw
tlp, Ψo
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). Ψw
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. |
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