title: Potassium nitrate application alleviates sodium chloride stress in winter wheat cultivars differing in salt tolerance.
abstract: A sand culture experiment was conducted to answer the question whether or not exogenous KNO(3) can alleviate adverse effects of salt stress in winter wheat by monitoring plant growth, K(+)/Na(+) accumulation and the activity of some antioxidant enzymes. Seeds of two wheat cultivars (CVs), DK961 (salt-tolerant) and JN17 (salt-sensitive), were planted in sandboxes and controls germinated and raised with Hoagland nutrient solution (6 mM KNO(3), no NaCl). Experimental seeds were exposed to seven modified Hoagland solutions containing increased levels of KNO(3) (11, 16, 21 mM) or 100 mM NaCl in combination with the four KNO(3) concentrations (6, 11, 16 and 21 mM). Plants were harvested 30 d after imbibition, with controls approximately 22 cm in height. Both CVs showed significant reduction in plant height, root length and dry weight of shoots and roots under KNO(3) or NaCl stress. However, the combination of increased KNO(3) and NaCl alleviated symptoms of the individual salt stresses by improving growth of shoots and roots, reducing electrolyte leakage, malondialdehyde and soluble sugar contents and enhancing the activities of antioxidant enzymes. The salt-tolerant cultivar accumulated more K(+) in both shoots and roots compared with the higher Na(+) accumulation typical for the salt-sensitive cultivar. Soluble sugar content and activities of antioxidant enzymes were found to be more stable in the salt-tolerant cultivar. Our findings suggest that the optimal K(+)/Na(+) ratio of the nutrient solution should be 16:100 for both the salt-tolerant and the salt-sensitive cultivar under the experimental conditions used, and that the alleviation of NaCl stress symptoms through simultaneously applied elevated KNO(3) was more effective in the salt-tolerant than in the salt-sensitive cultivar.
authors.affiliation: Key Laboratory of Vegetation and Environmental Change, Institute of Botany, the Chinese Academy of Sciences, Xiangshan, Beijing, China.
authors.forename: Yanhai
authors.initials: Y
authors.lastname: Zheng
authors.forename: Aijun
authors.initials: A
authors.lastname: Jia
authors.forename: Tangyuan
authors.initials: T
authors.lastname: Ning
authors.forename: Jialin
authors.initials: J
authors.lastname: Xu
authors.forename: Zengjia
authors.initials: Z
authors.lastname: Li
authors.forename: Gaoming
authors.initials: G
authors.lastname: Jiang
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D018533:Biomass; D002338:Carotenoids / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D002734:Chlorophyll / Q000378:metabolism; D004573:Electrolytes; D007477:Ions; D015227:Lipid Peroxidation / Q000187:drug effects; D008315:Malondialdehyde / Q000378:metabolism; D009566:Nitrates / Q000494:pharmacology*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000201:enzymology; D011134:Polysaccharides / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D017680:Potassium Compounds / Q000494:pharmacology*; D055049:Salt Tolerance / Q000187:drug effects*; D012621:Seasons; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D012995:Solubility / Q000187:drug effects; D013312:Stress, Physiological / Q000187:drug effects*; D014908:Triticum / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology*; D014867:Water
chemical_list: D000975:Antioxidants; D004573:Electrolytes; D007477:Ions; D009566:Nitrates; D011134:Polysaccharides; D017680:Potassium Compounds; D014867:Water; D002734:Chlorophyll; D002338:Carotenoids; D012965:Sodium Chloride; D008315:Malondialdehyde; D012964:Sodium; C023844:potassium nitrate; D011188:Potassium