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Anomalous Diurnal Patterns of Stem Xylem Water Potentials in Larrea tridentata
Author(s) -
Syvertsen James P.,
Cunningham G. L.,
Feather T. V.
Publication year - 1975
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1934709
Subject(s) - larrea , xylem , photosynthesis , botany , soil water , water potential , biology , environmental science , horticulture , ecology , shrub
Diurnal stem xylem H 2 O potentials of Larrea tridentata (DC.) Cov. were measured with a pressure chamber during the summers of 1973, 1974. Plants growing in dry soils had minimum stem xylem H 2 O potentials at night and maximum values during the daylight hours. Vertical H 2 O vapor movements in the soil profile in response to temperature gradients may be implicated although further data are needed to establish their role conclusively. Water vapor apparently moves up out of the rooting One at night and back down into the rooting zone during the day. The occurrence of this phenomenon probably enhances the ability of Larrea shrubs to maintain photosynthetic activity when soil H 2 O potentials are low and makes questionable the use of predawn stem xylem H 2 O potential measurements to assess seasonal trends in plant H 2 O status.