Salinity, alkalinity and their combined stress effects on germination and seedling growth attributes in oats (Avena sativa).

Context: Under natural field conditions, plants confront the co-occurrence of stresses. A comprehensive insight into combined-stress tolerance is requisite to developing stress resilience in cultivars of oats (Avena sativa L.) for saline–alkaline soil. Aims: This study was undertaken to characterise diverse oat genotypes for seedling growth attributes under two saline and alkaline concentrations and under combined saline–alkaline conditions. Methods: We screened 105 accessions of the genus Avena with the following treatments: control, reverse osmosis water; moderate salinity (50 mM); high salinity (100 mM); moderate alkalinity (15 mM); high alkalinity (30 mM); combined moderate salinity–alkalinity (50 mM + 15 mM); and combined high salinity–alkalinity (100 mM + 30 mM). For saline treatments, NaCl and Na2SO4 salts were used in equimolar concentrations, and for alkaline treatments, NaHCO3 and Na2CO3. Key results: Analysis of variance showed significant (P ≤ 0.001) variation among treatments and genotypes. Principal component analysis revealed 83.3% of the total genetic variation accounted for in the first two principal components. Correlation analysis showed a significant positive correlation between final germination percentage and seedling vigour index. Stress tolerance index identified tolerant and sensitive oat genotypes under high saline and alkaline stress, and multi-trait stability analysis confirmed the stability of performance of some genotypes under the imposed treatments. Conclusions: According to the stress tolerance index and multi-trait stability analysis, genotypes IG-20-477, OS-377, IG-20-798 and IG-20-575 were found suitable for high saline–alkaline stress. Implications: The identified tolerant oat genotypes can be used as donors for the development of stress-resilient oat cultivars, and for generating mapping populations in oat. Saline–alkaline soil is a global threat to crop production, and the combined effects of salinity and alkalinity may be greater than individual effects, with seed germination the most sensitive stage to these stresses. We evaluated oat germplasm under combined stress in order to identify and select lines with better seed germination and high vigour. The stress-tolerant lines identified could serve as base material for stress-tolerance breeding programs. [ABSTRACT FROM AUTHOR]