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Responses of apple leaf stomata to environmental factors
Author(s) -
WARRIT B.,
LANDSBERG J. J.,
THORPE M. R.
Publication year - 1980
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/1365-3040.ep11580397
Subject(s) - stomatal density , irradiance , horticulture , vapour pressure deficit , botany , cultivar , stomatal conductance , biology , transpiration , photosynthesis , physics , optics
. Stomatal conductances ( g s ) were measured on the leaves of 3–4 year old Golden Delicious trees and of seedlings of two other cultivars. Measurements were made on container grown trees in the field with a diffusion porometer in 1975 and 1976, and in controlled conditions in a leaf chamber in the laboratory in 1976. Stomatal densities in the Golden Delicious leaves were assessed from scanning electron micrographs. Stomatal density on extension shoot leaves was higher than on other leaf types after June. The response to irradiance shown by both the porometer and the leaf chamber results could be described by a rectangular hyperbola:where g max is maximum conductance and β indicates the sensitivity of g s to photon influx density ( Q p ). The values of β were in the range 60–90 μmol m −2 s −1 . There was no evidence that apple stomata are sensitive to temperature per se, but g s was reduced by increasing leaf to air vapour pressure deficits ( D ). There was a linear relationship between g s and D which was not attributable to feed‐back to leaf water potential (ψ L ) as the latter did not affect g s until a threshold of about −2.0 to −2.5 MPa was reached. Conductance generally declined with increasing ambient CO 2 concentration.