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Extramural Research

Grantee Research Project Results

Grantee Research Project Results

Ecophysiology of Salinity and Boron Tolerance of Equisetum giganteum in the Atacama Desert, Northern Chile

EPA Grant Number: U916209
Title: Ecophysiology of Salinity and Boron Tolerance of Equisetum giganteum in the Atacama Desert, Northern Chile
Investigators: Husby, Chad E.
Institution: Florida International University
EPA Project Officer: Just, Theodore J.
Project Period: January 1, 2003 through January 1, 2006
Project Amount: $89,225
RFA: Minority Academic Institutions (MAI) Fellowships for Graduate Environmental Study (2003)
Research Category: Academic Fellowships , Fellowship - Natural and Life Sciences , Biology/Life Sciences

Description:

Objective:

The overall objective of this research project is to gain a broader understanding of salinity tolerance in plants by focusing on how an ancient and unique plant group copes with salinity stress. The specific objectives of this research project are to: (1) elucidate the water relations, water source usage, and photosynthetic physiology of Equisetum growing in saline and nonsaline habitats; (2) evaluate mineral uptake and composition of Equisetum in saline and nonsaline habitats; (3) compare water relations and salinity responses of Equisetum to those of plants associated with Equisetum in saline habitats; and (4) study experimentally the responses of Equisetum to salinity and boron stress.

High soil salinity is a major environmental stress for many wild and cultivated plants. Although extensive research exists on plant responses to salinity stress, almost all such studies have dealt with seed plants in part because seedless vascular plants (pteridophytes) rarely exhibit salinity tolerance. Therefore, it is intriguing that several members of the unique pteridophyte genus Equisetum, including Equisetum giganteum L., are able to grow in soils with relatively high salinity and boron levels. The small, but widespread, genus Equisetum comprises the only surviving members of an ancient class of pteridophytes.

Approach:

This research project will focus on the giant horsetail, Equisetum giganteum. This species is a major vegetation component in several river valleys of the Atacama Desert in Northern Chile with high salinity and boron levels. The field portions of this research project will combine measurements of soil water properties (e.g., salinity and boron concentration), plant physiology, and xylem anatomy. I will measure stem water potential, osmotic potential, transpiration, chlorophyll fluorescence, and stable carbon isotope composition of E. giganteum, and will relate these parameters to soil water properties. I will use stable hydrogen and oxygen isotopes as natural tracers to assess water source usage patterns. In addition, I will study hydraulic architecture and demography of E. giganteum stems. In the experimental components of this research project, I will compare the growth and physiology of E. giganteum plants originating from saline and nonsaline habitats in a range of salinity and boron levels. The effects of mineral elements such as calcium, potassium, and silicon on salinity and boron tolerance also will be investigated experimentally.

Supplemental Keywords:

fellowship, boron tolerance, Equisetum giganteum, Atacama Desert, northern Chile, salinity tolerance, salinity stress, pteridophytes, mineral uptake.

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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