Premium
Drought response of two Mexican oak species, Quercus laceyi and Q. sideroxyla (Fagaceae), in relation to elevational position
Author(s) -
Poulos H. M.,
Goodale U. M.,
Berlyn G. P.
Publication year - 2007
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.94.5.809
Subject(s) - fagaceae , biology , botany
To investigate the relationship between the altitudinal distribution of Quercus laceyi and Q. sideroxyla and their physiological responses to drought, we measured relative water content (RWC), water potentials (Ψ predawn and Ψ midday ), photosynthesis ( A max ), stomatal conductance ( g ), chlorophyll fluorescence ( F v / F m ), and spectral reflectance (400–1100 nm) five times during a 7 wk acute drought. Quercus laceyi was drought tolerant, while Q. sideroxyla was a drought avoider; Q. laceyi tolerated lower RWC ( Q. sideroxyla = 54%, Q. laceyi = 44%), Ψ pd ( Q. sideroxyla = −2.6 MPa, Q. laceyi = −3.3 MPa), and Ψ md ( Q. sideroxyla = −4.5 MPa, Q. laceyi = −6.6 MPa). The F v / F m also declined first in Q. sideroxyla in wk 6, whereas F v / F m did not decline in Q. laceyi until wk 7. A max and g fell in wk 4, 6, and 7 in drought seedlings of both species, suggesting a decline in CO 2 assimilation during the drought. Leaf spectral reflectance increased with time in response to decreases in leaf photosynthetic pigment concentrations in latter weeks of the drought. The results suggest a close association between the altitudinal distributions of these species and their adaptation to water stress.