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The role of nitrogen (N) in inducing salt stress tolerance in plants is not well understood, and the question is more complicated in saffron (Crocus sativus L.), which is sensitive to both nitrogen rates and salinity. The present study was conducted to investigate the effects of different N (0, 50 and 150 kg ha−1) supplies on saffron growth and ions concentration in shoots under several salt stress levels (0, 3, 6 and 9 dS m−1). Salinity negatively affected plant growth assessed by leaves number, leaves length, shoot dry weight, corms number and corms weight. Moreover, there was a clear direct correlation between higher salinity value and less plant growth. Different effects due to salinity and nitrogen were evident in terms of the number and length of leaves during the growing season from day 60 after first irrigation (DAF) and achieved a peak after 90 DAF. Salt stress also affected the ions balance, as Na+, Cl− and Ca2+ were enhanced and K+ was reduced, thereby damaging the plants. Nitrogen partially mitigated the negative impacts of salinity on plant growth and ions balance, although this compensatory effect was observed when nitrogen supply was set at 50 kg N ha−1. For example, in 2019–2020, the losses in shoot dry weight due to 9 dS m−1 salinity amounted to 47%, 44% and 54%, at 0, 50 and 100 kg N ha−1 respectively, thus indicating a less negative effect of salinity at 50 kg N ha−1. Moreover, at 100 kg N ha−1 the negative effect of salinity was stronger for six and nine dS m−1. Our findings suggested that the optimum N supply (50 kg N ha−1) strengthened the plant under non-saline and moderately saline (6 dS m−1) conditions, and consequently improved salt tolerance. [ABSTRACT FROM AUTHOR]

Oxidative status of salicylic acid (SA) treated barley (Hordeum vulgare) plants grown under saline conditions was examined in a two-year field study during 2012-2013 and 2013-2014 growing seasons. Salinity caused a marked oxidative stress which was manifested as increased concentration of hydrogen peroxide (H2O2) and reduced grain yield of barley. Barley plants induced antioxidant system to tolerate salt stress, so that activities of four antioxidant enzymes: peroxidase, catalase, superoxide dismutase and glutathione reductase were enhanced by 22%, 28%, 57% and 44% in the first and by 33%, 20%, 45% and 68% in the second year, respectively. Foliar application of SA in concentration over 0.5 mM enhanced the activities of all four antioxidant enzymes and reduced H2O2 content and so enhanced yield. However, higher concentrations of SA reduced grain yield in salt stressed plants in both years, which could be attributed to the negative interaction of antioxidant enzymes with higher concentrations of SA as a non-enzymatic antioxidant. Furthermore, SA is in benzoic acid group and at very higher concentrations can act as an herbicide. It was concluded that SA modulated the oxidative stress through enhanced activities of antioxidant enzymes and reduced the salt-induced adverse effect thereby improving grain yield. [ABSTRACT FROM AUTHOR]

Although the effects of salicylic acid (SA) on increasing plant growth in saline conditions have been well known, the mechanisms of induction of salinity tolerance, especially in quinoa ( Chenopodium quinoa Willd.), are not fully understood. In the present work, two quinoa genotypes (Titicaca and Giza1) were treated with different SA concentrations (0, 0.75, and 1.5 mM) under varied irrigation water salinities (0, 7, 14, and 21 dS m -1 ). Salinity decreased shoot and root growth, potassium (K + ) concentration, and potassium to sodium ratio (K/Na) and increased sodium (Na + ) and chlorine (Cl - ) concentrations in both cultivars. Calcium (Ca 2+ ) and magnesium (Mg 2+ ) concentrations increased in 7 dS m -1 but decreased in higher salinities. The growth and salinity tolerance of Giza1 were higher, while the growth of Giza1 increased and of Titicaca decreased in high salinity. Salicylic acid at 0.75-mM concentration increased shoot and root growth and improved the ions concentration in favor of the plant, while the 1.5-mM concentration either had no significant effect or had a negative impact. The ions distribution estimated by K/Na selectivity and storage factor (SF) indicated quinoa accumulated more ions in roots under saline conditions. Salicylic acid increased NaSF, ClSF, and MgSF and decreased KSF and CaSF, meaning less Na + , Cl - , and Mg 2+ and more K + and Ca 2+ transferred to shoots in SA-treated plants. Importantly, Giza1, as the more tolerant cultivar, had higher NaSF and ClSF and lower KSF, CaSF, and MgSF. In general, the concentrations of ions in roots were higher than in shoots. The results indicated more ions accumulation in the root could be one of the most important mechanisms of salinity tolerance in quinoa, and the more tolerant cultivar (Giza1) transferred less Na + and Cl - and more K + and Ca 2+ and Mg 2+ to the shoot.