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Salt resistance is determined by osmotic adjustment and abscisic acid in newly developed maize hybrids in the first phase of salt stress
Author(s) -
De Costa Weerathunga,
Zörb Christian,
Hartung Wolfram,
Schubert Sven
Publication year - 2007
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.2007.00962.x
Subject(s) - shoot , abscisic acid , sucrose , turgor pressure , osmotic pressure , fructose , salt (chemistry) , horticulture , hybrid , cultivar , botany , salinity , chemistry , osmoregulation , biology , food science , biochemistry , gene , ecology
This study investigated the mechanisms of salt resistance of four maize ( Zea mays L.) hybrids [cultivar (cv.) Pioneer 3906 and newly developed hybrids SR03, SR12 and SR13] during the first phase of salt stress. Plants were grown in aerated nutrient solutions at 1 m M Na + (control) and 100 m M Na + (salt stress). Stress was imposed in 25 m M steps and plants were harvested after 2 days at 100 m M Na + . At 100 m M Na + the area of the fourth leaf, which developed under salt stress, did not change significantly in SR03 and SR12 whereas significant reductions were observed in cv. Pioneer 3906 and SR13. Concentrations of assimilates (i.e. glucose, fructose and sucrose) in the shoot sap were significantly greater under salt stress in SR03 and SR12. However, the greater assimilate supply was not responsible for their salt resistance as there were no significant reductions in assimilate concentrations even in the other two genotypes. Shoot turgor and growth were maintained in SR03 and SR12 at 100 m M Na + through significant increases in osmolality of the shoot sap. Concentrations of free ABA and ABA‐glucose esters (ABA‐GE) in the growing region of the fourth leaf increased significantly under salt stress in all genotypes. Leaf area at 100 m M Na + , expressed as a percentage of that at 1 m M , showed significant positive relationships with free ABA (R 2 = 0.62) and the sum of free ABA and ABA‐GE (R 2 = 0.65). Results of this study indicate clearly that a combination of partial osmotic adjustment, a possible reduction of the sensitivity of leaf growth under salt stress to increased ABA concentrations and a growth‐promoting function regulated by ABA is responsible for salt resistance in the first phase of salt stress. Genotypic variation in these mechanisms can be utilized to breed salt‐resistant genotypes in maize.