Salinity is one of the environmental factors limiting plant growth and development. Biochar has various effects on the chemical properties of soil and through soil fertility enhancement, can enhance plant productivity. This study was aimed to study the effect of biochar on the growth, physiological traits and mineral nutrient contents of summer savory (Satureja hortensis L.) and some chemical and elemental properties of the soil under salinity condition. Thus, a pot factorial experiment based on a completely randomized design with four replications was performed. Experimental treatments included three levels of biochar (non-biochar, 1 and 2% of total pot mass) and four different NaCl levels (0, 3, 5 and 7 dSm-1). The results showed that the growth traits (fresh and dry weight of the shoots and roots, main root length and volume) and leaf nutrients of summer savory were improved by increasing soil biochar (especially 2% of total pot mass) under salinity stress. Using biochar as 2% of total pot mass, at 5 dSm-1 increased proline content. In addition, this study indicated that soils containing biochar were rich in nutrients content and showed the highest pH (8.18), OC (1.63%) and N content (0.14%) at 2% biochar under no salinity. The highest EC (29.8 dSm/m), CEC (10.6 Cmol(+) kg-1), Ca2+ (45.4 meq/L), Mg2+ (32.4 meq/L), Na+ (180 meq/L) and Cl- (318 meq/L) were observed at 7 dSm-1 salinity by using 2% biochar. In general, biochar can modify the soil nutrient situation to overcome the detrimental effects of NaCl. The positive effect of biochar on the growth, nutrient uptake, and soil properties encourage the application of biochar to overcome nutrient deficiency and improve the plant growth.

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