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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVED PLANT GENETIC RESOURCES FOR PASTURES AND RANGELANDS IN THE TEMPERATE SEMIARID REGIONS OF THE WESTERN U.S. Title: Characterization of physiological responses of two alfalfa half-sib families with improved salt tolerance

Authors
item Anower, M -
item Mott, Ivan
item Peel, Michael
item Wu, Yajun -

Submitted to: Plant Physiology and Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 26, 2013
Publication Date: July 13, 2013
Citation: Anower, M.R., Mott, I.W., Peel, M., Wu, Y. 2013. Characterization of physiological responses of two alfalfa half-sib families with improved salt tolerance. Plant Physiology and Biochemistry. doi: 10.1016/j.plaphy.2013.06.026.

Interpretive Summary: Soil salinity is a global issue that is threatening crop production. Alfalfa is a major forage crop worldwide that is relatively sensitive to soil salinity. Improved alfalfa cultivars with high production on saline soil will benefit many producers and land managers and increase productivity of marginally saline soils. This study reports physiological characterization of two selected experimental alfalfa lines developed to survive in high saline conditions. Both lines grow better under salt treatment compared to their parents having longer stems and more leaves. The improved growth is associated with higher accumulation of chlorophyll content. Both lines also showed improved capability to maintain water status or avoid wilting when growing under salt stress. The two lines differ in regulation of sodium uptake and movement through the plant system. The lines differ in the accumulation of other salt ions that may be important in the regulation of plant function and salt tolerance. This study provides support of improved salt tolerance in these experimental lines and suggests that the two lines maintain proper ion balance within the plant cells but have different mechanisms of coping with high salinity.

Technical Abstract: Increasing soil salinity is a global issue that threatens crop production. Alfalfa (Medicago sativa L.) is a major forage crop worldwide that is relatively sensitive to soil salinity. Improved cultivars with high production on saline soil will benefit many producers and land managers. This study reports physiological characterization of two selected experimental lines, CS15-2 and BC11-1, developed to survive in high saline conditions. Both lines grow better under salt treatment compared to their parents as shown by 15% and 16% longer stem length and 35% and 26% greater leaf number for CS15-2 and BC11-1, respectively. This improved growth is associated with 22% and 20% greater accumulation of chlorophyll content in the CS15-2 and BC11-1, respectively. Both lines also showed improved capability to maintain water status while CS15-2 and BC11-1 parents had 5% and 10% reductions in relative water content under salt stress, respectively. The two lines showed differences in Na+ accumulation after salt treatment; the Na+ content increased by 48% in CS15-2 but did not change in BC11-1 as compared to their respective parents. These data suggest that these two lines differ in regulation of Na+ uptake and/or transport but the difference in Na+ content in the shoots may not be the key to determining their salt tolerance. Under salt stress, CS15-2 inorganic ion concentrations of Ca2+, K+, Mg2+, and Si+ did not change while its parents generally decreased BC11-1 maintained K+/Na+ and Ca2+/Na+ ratios, while its parents showed 59% and 69% decrease in these ion ratios, respectively. This study provides physiological support of improved salt tolerance in these experimental lines and suggests that the two lines maintain ion homeostasis but have different mechanisms of coping with high salinity.

Last Modified: 10/24/2014
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