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.

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The olive oil processing industry’s liquid effluents (OMW) have a polluting capacity for the ecosystems. This study aimed to evaluate the physicochemical quality of OMW of two varieties of separated and combined olives cultivated in Khenchela Eastern Algeria, from the cold extraction of the olive oil extraction system. These was to determine their degree of pollution and biodegradability during one year of storage at ambient temperature to recommend the correct treatment for each storage time. Results of the measured parameters pH, EC,TSS percent, H ₂ O percent, lipids, DM, OM, MM, VM, COT percent, NTK percent, C/N, BOD ₅ , COD, BI, TOM, BOD ⁵ /COD show that wastewater from olive oil mills has an acid pH, and they are very loaded with organic matter evaluated in terms of COD and BOD ₅ , quite filled with minerals. The storage of olive mill waste can reduce progressively the pollution caused by this waste. Whereas during one year, the reduction rate of COD, BOD ₅ , TOM, BI, is respectively 29.4%, 54.8%, 39.16%, 54.2%, but C/N, BOD ₅ /COD continue to increase as well as pH that continues to decrease during the storage. Accordingly, storing olive mill waste during a year reduces its pollution rate, so it is slowly biodegradable. When disposing of it, an adequate treatment procedure must be required to protect the environment.

The effects of irrigation with saline water were studied on barley plants cultivated under arid conditions at the Institute of Arid Regions located in the South East of Tunisia. Two barley accessions (Karkeni and Bengardeni) and three regimes of irrigation as a function of the cultural evapotranspiration ETc (T0: 100% ETc, T1: 75% ETc and T2: 50% ETc) were used. Several parameters – gas exchange (A, E and gs), total flavonoid contents (TFC), total phenolic contents (TPC), phenolic compounds, antioxidant activity (DPPH and ABTS) and grain yield (GY) – were used to assess the effects of the studied factors on barley plants. Gas exchange parameters (A, E and gs) vary significantly between treatments. Salinity stress had no significant effect on TPC and TFC. Phenolic compounds varied significantly between treatments and accessions. In addition, their antioxidant activity based on DPPH and ABTS scavenging assays increased and are more important in Karkeni than Bengardeni under soil salinity. In addition, soil salinity decreased yield and yield components. Karkeni was more productive than Bengardeni.

Drought and salinity are the two major abiotic stresses limiting barley growth and productivity. In order to understand the physiological and biochemical traits associated with deficit irrigation using saline water in barley at heading stage, this study was performed under field conditions to treat two barley landraces, “Karkeni” (origin: irrigated) and “Bengardeni” (origin: rainfed in arid area), with three irrigation treatments as a function of cultural evapotranspiration ETc (T0: 100% ETc, T1: 75% ETc and T2: 50% ETc). In both barley landraces, deficit irrigation with saline water (T1 and T2 treatments) significantly decreased net photosynthetic rate (A), transpiration rate (E), stomatal conductance (gs), K⁺ content, K⁺/Na⁺ ratio and grain yield (GY); by contrast, DPPH and ABTS scavenging capacities as well as Na⁺ content were increased, concomitant with a landrace-dependent variation in phenolic compounds composition. Interestingly, under T1 and T2 treatments, “Karkeni” had the lowest A, E, gs and K⁺/Na⁺ ratio, and the highest Na⁺ content and GY. Overall, at heading stage, salt accumulation in deficit irrigated soils with saline water significantly reduces GY of barley by influencing gas exchange, phytochemical profiles and antioxidant activities, in a landrace-dependent manner.