Mitigating Salinity Stress in Barley (Hordeum vulgare L.) through Biochar and NPK Fertilizers: Impacts on Physio-Biochemical Behavior and Grain Yield

Increased soil salinity significantly inhibits crop production around the world. Over the last decade, biochar has been used in agriculture to improve plant productivity, soil quality, and as an alternative to plant amendment. This study was aimed to study the effect of biochar, NPK, and their combination on the growth, physio-biochemical traits, mineral contents, and grain yield of barley (Hordeum vulgare L.). Thus, a pot factorial experiment based on a completely randomized design with three replications was performed. Experimental treatments included four levels of biochar (0, 2, 5 and 10% of total pot mass), four different NaCl levels (0, 75, 125, and 200 mmol L−1), and with or without NPK fertilizer. The results showed that a negative effect on gas exchange parameters, photosynthetic pigments, SPAD value, minerals contents, and grain yield of barley under salinity treatments. In addition, our funding showed the negative effect on biochemical traits such as proline, soluble sugars, individual sugar, and phenolic compounds. The use of biochar, combined with NPK fertilizers, considerably increases these parameters and especially improves barley grains yield under severe salinity conditions (200 mM) with a dose of 2% and 5% (394.1 and 280.61 g m−2, respectively) of total pot mass. It is concluded that biochar amendment could be a promising practice to enhance barley growth under severe saline irrigation and NPK fertilization regimes.