Changes in foliar spectral reflectance and chlorophyll fluorescence of four temperate species following branch cutting.

Spectral reflectance and chlorophyll fluorescence are rapid non-invasive methods that can be used to quantify plant stress. Because variation in ambient light (e.g., diurnal patterns of solar radiation) may have a confounding effect on these measurements, branches are often excised in the field and then measured under controlled conditions in the laboratory. We studied four temperate tree species (Abies balsamea (L.) Mill. (balsam fir), Betula papyrifera var. cordifolia (Regel) Fern. (paper birch), Picea rubens Sarg. (red spruce) and Sorbus americana Marsh. (mountain-ash)) to determine how quickly reflectance and fluorescence change following branch cutting. We hypothesized that conifer species, which have tough xeromorphic foliage, would exhibit changes more slowly than broadleaf species. Furthermore, we hypothesized that keeping broadleaf samples cool and moist would delay the onset of reflectance and fluorescence changes. In one set of experiments, we did not use any treatments to maintain the freshness of cut branches. During the first 12 h following cutting, changes in reflectance and fluorescence were slight for all species. Two or 3 days after branch cutting, the two conifers still showed only small changes in the ratio of variable to maximum fluorescence (Fv/Fm) and most reflectance indices, whereas paper birch and mountain-ash showed larger and more rapid declines in Fv/Fm and most reflectance indices. We attribute these declines to loss of water. As a consequence of xeromorphic leaf structure, the conifers were better able to minimize water loss than the two broadleaf species. In another experiment, paper birch that had been kept cool and moist after cutting showed only slight changes in fluorescence and reflectance, even after 3 days, indicating that with careful handling the time interval between collection and measurement of reflectance and fluorescence of many broadleaf specimens can be extended to several days. We conclude that measurements of reflectance and fluorescence need not be made in situ to be accurate and reliable.

[1]  A. Gitelson,et al.  Detection of Red Edge Position and Chlorophyll Content by Reflectance Measurements Near 700 nm , 1996 .

[2]  J. Dungan,et al.  Exploring the relationship between reflectance red edge and chlorophyll content in slash pine. , 1990, Tree physiology.

[3]  S. Long,et al.  Chlorophyll Fluorescence as a Probe of the Photosynthetic Competence of Leaves in the Field: A Review of Current Instrumentation , 1989 .

[4]  Andrew D. Richardson,et al.  An evaluation of noninvasive methods to estimate foliar chlorophyll content , 2002 .

[5]  S. Blankenship,et al.  Attributes of water additives affect postharvest needle retention of Fraser fir , 1991 .

[6]  A. Richardson,et al.  Spectral reflectance of Picea rubens (Pinaceae) and Abies balsamea (Pinaceae) needles along an elevational gradient, Mt. Moosilauke, New Hampshire, USA. , 2001, American journal of botany.

[7]  Gregory A. Carter,et al.  Responses of leaf spectral reflectance to plant stress. , 1993 .

[8]  B. Datt.  Remote Sensing of Chlorophyll a, Chlorophyll b, Chlorophyll a+b, and Total Carotenoid Content in Eucalyptus Leaves , 1998 .

[9]  G. James Collatz,et al.  Regulation of branch-level gas exchange of boreal trees: roles of shoot water potential and vapor pressure difference. , 1997, Tree physiology.

[10]  J. Peñuelas,et al.  Assessment of photosynthetic radiation‐use efficiency with spectral reflectance , 1995 .

[11]  Josep Peñuelas,et al.  Visible and near-infrared reflectance techniques for diagnosing plant physiological status , 1998 .

[12]  Mitchell,et al.  Foliar temperature-respiration response functions for broad-leaved tree species in the southern Appalachians. , 1999, Tree physiology.

[13]  David W. Lee,et al.  Why leaves turn red in autumn. The role of anthocyanins in senescing leaves of red-osier dogwood. , 2001, Plant physiology.

[14]  G. Carter.  Ratios of leaf reflectances in narrow wavebands as indicators of plant stress , 1994 .

[15]  C. Field,et al.  A narrow-waveband spectral index that tracks diurnal changes in photosynthetic efficiency , 1992 .

[16]  J. Gamon,et al.  The photochemical reflectance index: an optical indicator of photosynthetic radiation use efficiency across species, functional types, and nutrient levels , 1997, Oecologia.

[17]  R. Paull,et al.  Effect of temperature and relative humidity on fresh commodity quality , 1999 .

[18]  F. M. Danson,et al.  Spectral reflectance of dehydrating leaves: Measurements and modelling , 1997 .

[19]  G. Krause,et al.  Chlorophyll Fluorescence and Photosynthesis: The Basics , 1991 .

[20]  Govindjee,et al.  Chlorophyll A fluorescence transient as an indicator of water potential of leaves , 1981 .

[21]  J. Roden,et al.  Applications of Chlorophyll Fluorescence to Forest Ecology , 1995 .

[22]  A. Gitelson,et al.  Spectral reflectance changes associated with autumn senescence of Aesculus hippocastanum L. and Acer platanoides L. leaves. Spectral features and relation to chlorophyll estimation , 1994 .

[23]  P. G. Jarvis,et al.  STOMATAL CONDUCTANCE AND PHOTOSYNTHESIS IN A MATURE SCOTS PINE FOREST I. DIURNAL, SEASONAL AND SPATIAL VARIATION IN SHOOTS , 1985 .

[24]  P. Arp,et al.  Net photosynthesis and stomatal conductance of red spruce twigs before and after twig detachment , 1993 .

[25]  William D. Philpot,et al.  Yellowness index: An application of spectral second derivatives to estimate chlorosis of leaves in stressed vegetation , 1999 .

[26]  G. Carter.  PRIMARY AND SECONDARY EFFECTS OF WATER CONTENT ON THE SPECTRAL REFLECTANCE OF LEAVES , 1991 .

[27]  R. Jackson.  Remote sensing of biotic and abiotic plant stress , 1986 .

[28]  John A. Gamon,et al.  Assessing leaf pigment content and activity with a reflectometer , 1999 .

[29]  Serge Rambal,et al.  Exploring the relationships between reflectance and anatomical and biochemical properties in Quercus ilex leaves , 1999 .

[30]  P. Schaberg,et al.  Photosynthetic capacity of red spruce during winter. , 1998, Tree physiology.

[31]  G. A. Blackburn,et al.  Spectral indices for estimating photosynthetic pigment concentrations: A test using senescent tree leaves , 1998 .

[32]  W. R. Watts,et al.  Photosynthesis in Sitka Spruce (Picea sitchensis (Bong.) Carr.). VIII. Measurements of Stomatal Conductance and 14 CO 2 Uptake in Controlled Environments , 1978 .

[33]  A. Gitelson,et al.  Signature Analysis of Leaf Reflectance Spectra: Algorithm Development for Remote Sensing of Chlorophyll , 1996 .

[34]  D. Straeten,et al.  Seeing is believing: imaging techniques to monitor plant health. , 2001, Biochimica et biophysica acta.