Skip to main content
ARS Home » Research » Publications at this Location » Publication #258987
Title: Separating multiple, short-term deleterious effects of saline solutions to the growth of cowpea seedlings

Author
item KOPITTKE, PETER - Queensland University - Australia
item BLAMEY, F. PAX - Queensland University - Australia
item Kinraide, Thomas
item WANG, PENG - Chinese Academy Of Sciences
item REICHMAN, SUZIE - Royal Melbourne Institute Of Technology University
item MENZIES, NEAL - Queensland University - Australia

Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2010
Publication Date: 11/30/2010
Citation: Kopittke, P.M., Blamey, F.C., Kinraide, T.B., Wang, P., Reichman, S.M., Menzies, N.W. 2010. Separating multiple, short-term deleterious effects of saline solutions to the growth of cowpea seedlings. New Phytologist. 189:1110-1121.

Interpretive Summary: Reductions in plant growth due to salinity (mainly excessive sodium) are of global importance in natural and agricultural landscapes. Agricultural production is limited by salinity. Remediation of saline lands is difficult and expensive, but some improved cultural methods and some genetic improvements can increase production in unremediated soils. To provide a scientific basis for these improvements we undertook studies to better understand salinity restriction of growth. We observed multiple plant responses in saline environments to other salts (such as calcium, magnesium, and potassium). Calcium and potassium alleviated sodium toxicity at appropriate concentrations but aggravated toxicity at higher concentrations. Magnesium aggravates the toxicity at all but very low concentrations, and five separate physiological roles for calcium were discovered. Plants sense these toxins and ameliorate solutes at the root cell membrane surface where surface charges and electrical potentials play a dominant role. Electrostatic models developed by us will guide the cultural practices and breeding objectives for crop productivity in saline soils.

Technical Abstract: Reductions in plant growth due to salinity are of global importance in natural and agricultural landscapes. Short-term (48 h) solution culture experiments studied 404 treatments with seedlings of cowpea (Vigna unguiculata (L.) Walp. cv. Caloona) to examine the multiple deleterious effects of Ca, Mg, Na, or K. Growth was poorly related to activities in the bulk solution, but were closely related to activities at the outer surface of the plasma membrane (PM). The addition of Mg, Na, or K resulted in Ca deficiency in roots at PM-surface activities of Ca = 1.6 mM. Shoots were more sensitive to increases in osmolarity than were roots. Specific-ion toxicities also reduced growth; relative to PM-surface activities of Ca, the same level of growth reduction occurred at 1.5 times PM-surface activities of Mg, 3.2 times PM-surface activities of Na, or 29 times PM-surface activities of K. The addition of K, and Ca to a lesser extent, alleviated the toxic effects of Na. The data demonstrate that the short-term growth of cowpea seedlings in saline solutions may be limited by Ca deficiency, osmotic effects, and specific-ion toxicities, and that K and Ca alleviate Na toxicity. A multiple regression model related root growth to osmolarity and PM-surface activities of ions (R2 = 0.924), allowing quantification of their effects.