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Interactive Effects of Salinity and Substrate Phosphate on Soybean 1
Author(s) -
Grattan S. R.,
Maas E. V.
Publication year - 1984
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1984.00021962007600040038x
Subject(s) - salinity , shoot , phosphate , chlorosis , horticulture , saline , substrate (aquarium) , chemistry , glycine , salt (chemistry) , botany , biology , biochemistry , ecology , endocrinology , amino acid
Preliminary experiments at this laboratory indicated that salt injury of soybeans [ Glycine max (L.) Merr.) is strongly dependent upon the inorganic phosphate (Pi) concentration in the substrate. Inorganic phosphate concentrations that are commonly used in nonsaline solution cultures were lethal to ‘Kanrich’ and ‘Prize’ cvs. in saline media. A solution culture experiment was conducted in the greenhouse to examine the interactive effects of salinity (−0.04, −0.24, and −0.44 MPa osmotic potential) and substrate Pi (0.02,0.10,0.20, and 0.30 mmol L −1 ) on shoot and root growth, foliar injury, and tissue element concentration on five soybean cvs. [‘Clark’ (P‐sensitive), ‘Jackson’ (salt‐sensitive, P‐tolerant), ‘Lee’ (salt‐tolerant, P‐tolerant), ‘L63‐1677’ (P‐tolerant), and Kanrich]. Increased Pi had no effect on growth under nonsaline conditions but in the presence of salinity it significantly reduced shoot and root growth of Clark and Kanrich cvs. only. High salinity (−0.44 MPa) in combination with Pi ≥ 0.10 mmol L −1 killed both Clark and Kanrich cvs. However, at 0.02 mmol L −1 Pi and high salinity, no foliar injury was found on Kanrich and only slight chlorosis was found on Clark. In contrast, no foliar injury was apparent on Lee in any treatment. Inorganic phosphate increased the severity of injury in L63‐1677. Salinity greatly enhanced Pi accumulation in leaves and roots of Clark and Kanrich; whereas this effect was slight for the P‐tolerant cvs. Lee, Jackson, and L63‐1677. Injured Clark and Kanrich leaves contained abnormal amounts of P (400 to 800 mmol kg −1 , dry wt) indicating that the primary cause of injury was a salinity‐induced Pi toxicity. Salinity also induced considerable foliar injury on Jackson; yet the onset and severity was independent of the substrate Pi concentration. Unlike the mechanism of foliar injury in Clark and Kanrich, we suspect injury in Jackson was caused by Cl toxicity. The striking adverse interaction between salinity and phosphate is a critical factor in solution culture studies of plant tolerance to salinity. These results further demonstrate that important genetic differences exist among cultivars that greatly affect their susceptibility to Pi toxicity.