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Photosynthetic and stomatal responses of Avena sativa (poaceae) to a variable light environment
Author(s) -
Fay Philip A.,
Knapp Alan K.
Publication year - 1993
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 - 10.1002/j.1537-2197.1993.tb15380.x
Subject(s) - avena , transpiration , biology , stomatal conductance , poaceae , photosynthesis , water use efficiency , botany , agronomy , horticulture
The net photosynthetic (A), stomatal conductance to water vapor (g), water use efficiency (WUE = A/transpiration), and leaf water potential (ψ) responses of cultivated oats ( A vena saliva ) were determined under an experimental regime of alternating full sun (photosynthetic photon flux density, PPFD > 1,700 μ mol · m ‐2 ‐sec ‐1 ) and shade (300‐400 μ mol · m ‐2 · sec ‐1 PPFD). Less extensive measurements were made on winter wheat ( Triticum aestivum ) to test the generality of crop species' responses. The rates of stomatal opening/closing after changes in PPFD in A vena and Triticum were compared with previously determined rates for native grasses and forbs to assess how domestication might have altered stomatal dynamics. Characteristics of Avena under alternating sun and shade were 1) rapid fluctuations in A between full sun (~27 μ mol · m ‐2 · sec ‐1 ) and shade rates (~12 ‐13 μ mol · m 2 sec 1 ); 2) slower changes in g, causing progressive stomatal closure during the measurement sequence and possible stomatal limitation of A; 3) no change in leaf ψ; and 4) a net reduction in WUE. Triticum had similar sun/shade A, g, and WUE dynamics, except that Triticum stomata returned to full‐sun g between shade periods. The rates of change of g in Avena and Triticum were lower than for some desert and subalpine native species, but were similar to rates for species in adjoining native habitat. The basic stomatal dynamics of Avena and Triticum may typify many cultivated C, species, and these data indicate that crop stomatal behavior has not diverged significantly from that of native species.