Evaluation of Salt Tolerance and Its Relationship with Carbon Isotope Discrimination and Physiological Parameters of Barley Genotypes

ABSTRACT

Soil management through the cultivation of salt-tolerant plants is a practical approach to combat soil salinization. In this study, salt tolerance of 35 barley (Hordeum vulgare L.) genotypes was tested at four salinity levels (0, 100, 200, and 300 mM NaCl in Hoagland nutrient solution) at two growth stages (germination and vegetative). The relationship between salinity tolerance and carbon isotope discrimination (CID) was also accessed. Results of the study carried out under laboratory conditions showed that a negative linear relationship was observed between salt concentration and germination as well as other growth parameters. Some genotypes showed good salt tolerance at germination but failed to survive at seedling stage. However, five genotypes, namely, Jau-83, Pk-30109, Pk-30118, 57/2D, and Akermanns Bavaria showed better tolerance to salinity (200 mM) both at germination and at vegetative growth stage. The salt tolerance of these barley genotypes was significantly correlated with minimum decrease in K⁺:Na⁺ ratio in plant tissue with increase in the root zone salinity. However, the case was reversed in sensitive genotypes. CID was decreased linearly with increase in root zone salinity. However, salt-tolerant genotypes maintained their turgor by osmotic adjustment and by minimum increase in diffusive resistance and showed minimum reduction in CID (Δ) with gradual increase in rooting medium salt concentration. Results suggested that the tolerant genotypes make osmotic adjustments by selective uptake of K⁺ and by maintaining a higher K⁺:Na⁺ ratio in leaves. Moreover, CID technique can also be good criteria for screening of salt-tolerant germplasm.

KEYWORDS:

• Barley
• carbon isotope discrimination
• K⁺:Na⁺ ratio
• NaCl salinity
• osmotic potential
• salt tolerance

Acknowledgments

This work was partly funded by IAEA Research Contract-17637 “Managing saline irrigation water involving isotopic techniques for sustainable food/feed and fuel production on salt affected soil in semiarid environment.” The technical assistance of Mr. Khawer Maqsood, Mr. Naeem Abbas, and Mr. Munawar Hussain in experimental work is gratefully acknowledged.

Additional information

Funding

This work was supported by the International Atomic Energy Agency [IAEA-17637].

Notes on contributors

Ayesha Mustafa

Ayesha Mustafa Position& Department: Junior Scientist, Nuclear Institute for Agriculture and Biology, Faisalabad, Pakistan Interests: Saline agriculture, selection of crops for salt affected soils. Testing of saline agriculture technology in salt affected areas

Khalid Mahmood

Khalid Mahmood Position& Department: Deputy Chief Scientist (R), Nuclear Institute for Agriculture and Biology, Faisalabad, Pakistan Interests: Selection of filed crops, trees, shrubs and grasses for salt affected soils and use of saline ground water. Reclamation of salt affected soils and poor quality water

Wajid Ishaque

Wajid Ishaque Position& Department: Principal Scientist, Nuclear Institute for Agriculture and Biology, Faisalabad, Pakistan Interests: His main focus is on selection and characterization of crop genotypes against salinity, drought, and other abiotic stresses.