Spectral reflectance and leaf internal structure changes of barley plants due to phytoextraction of zinc and cadmium

The focus of our research is to seek spectral signatures that indicate the impact and content of heavy metals in the leaves and canopies of living plants during the process of phytoremediation. Potted plants of barley (Hordeum vulgare) were grown for 5–6 weeks before being subjected to metal treatments of Zn and Cd. Diffuse reflectance spectra (350–2500 nm) of the plant canopies were collected daily using a portable spectroradiometer throughout the treatment period. Foliar structural changes of Zn‐treated plants included a decrease in intercellular space, palisade and epidermal cell size while Cd‐treated plants displayed fewer structural changes in leaf. Spectral analysis revealed that the band ratios at 1110 nm to that at 810 nm might be used as an indicator of the accumulation of certain metals in plant shoots. Normalized Difference Vegetation Index (NDVI) and leaf‐water‐content indices examined as part of our spectral analysis were not able to distinguish plants treated with different metals. Our ratio index R1110/R810, on the other hand, correlates closely with the magnitude of leaf structural changes. This study suggests that the infrared reflectance spectrum (800–1300 nm) of plant canopy might provide a non‐intrusive monitoring method for the physiological status of plants grown on heavy metal contaminated soil.

[1]  C. I. Rich.  Soil Chemical Analysis , 1958 .

[2]  W. Allen,et al.  Electrooptical remote sensing methods as nondestructive testing and measuring techniques in agriculture. , 1968, Applied optics.

[3]  E. B. Knipling.  Physical and physiological basis for the reflectance of visible and near-infrared radiation from vegetation , 1970 .

[4]  J. Woolley.  Reflectance and transmittance of light by leaves. , 1971, Plant physiology.

[5]  M. M. Schreiber,et al.  Reflectance and internal structure of leaves from several crops during a growing season. , 1971 .

[6]  M. M. Schreiber,et al.  Diffuse Reflectance Hypothesis for the Pathway of Solar Radiation Through Leaves1 , 1973 .

[7]  J. A. Schell,et al.  Monitoring the Vernal Advancement and Retrogradation (Green Wave Effect) of Natural Vegetation. [Great Plains Corridor] , 1973 .

[8]  H. Gausman,et al.  Reflectance of leaf components , 1977 .

[9]  James Barber,et al.  Effects of heavy metals on the absorbance and reflectance spectra of plants , 1980 .

[10]  Edward J. Masuoka,et al.  The application of remote sensing to geobotanical exploration for metal sulfides; results from the 1980 field season at Mineral, Virginia , 1983 .

[11]  William J. Collins,et al.  Confirmation of the airborne biogeophysical mineral exploration technique using laboratory methods , 1983 .

[12]  Alexander F. H. Goetz,et al.  Remote sensing for exploration; an overview , 1983 .

[13]  Sheng-Huei Chang,et al.  Airborne biogeophysical mapping of hidden mineral deposits , 1983 .

[14]  L. Grant.  Diffuse and specular characteristics of leaf reflectance , 1987 .

[15]  C. Poschenrieder,et al.  Cadmium-Induced Structural and Ultrastructural Changes in the Vascular System of Bush Bean Stems , 1988 .

[16]  Jiyou Wu,et al.  Senescence and spectral reflectance in leaves of northern pin oak (Quercus palustris Muenchh.) , 1988 .

[17]  N. Milton,et al.  Arsenic- and selenium-induced changes in spectral reflectance and morphology of soybean plants , 1989 .

[18]  F. Stuart Chapin,et al.  Integrated Responses of Plants to Stress , 1991 .

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

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

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

[22]  A. Huete,et al.  A review of vegetation indices , 1995 .

[23]  Estimation of mineral content in natural grasslands by near infrared reflectance spectroscopy , 1995 .

[24]  Ilya Raskin,et al.  Phytoextraction: the use of plants to remove heavy metals from soils. , 1995, Environmental science & technology.

[25]  DETERMINATION OF THE CONTENT OF HAZARDOUS HEAVY METALS ON LARREA TRIDENTATA GROWN AROUND A CONTAMINATED AREA , 1996 .

[26]  A. Banin,et al.  Long-term transformations and redistribution of potentially toxic heavy metals in arid-zone soils incubated: I. Under saturated conditions , 1997 .

[27]  Stephen D. Ebbs,et al.  Phytoextraction of cadmium and zinc from a contaminated soil , 1997 .

[28]  R. W. Whitney,et al.  Indirect measures of plant nutrients , 1998 .

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

[30]  G. Asner.  Biophysical and Biochemical Sources of Variability in Canopy Reflectance , 1998 .

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

[32]  I. Raskin,et al.  Phytoremediation of toxic metals : using plants to clean up the environment , 2000 .

[33]  Alexander F. H. Goetz,et al.  Progress in hyperspectral imaging of vegetation , 2001, Optics East.

[34]  Y. R. Chen,et al.  Steady-state multispectral fluorescence imaging system for plant leaves. , 2001, Applied optics.

[35]  E. Hunt,et al.  Estimating near-infrared leaf reflectance from leaf structural characteristics. , 2001, American journal of botany.

[36]  D. Sims,et al.  Estimation of vegetation water content and photosynthetic tissue area from spectral reflectance: a comparison of indices based on liquid water and chlorophyll absorption features , 2003 .