Effect of parthenium hysterophorus biochar on the morphological and physiological properties of sorghum (Sorghum bicolor L.) under salinity stress

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Salinity stress is a considerable abiotic constraint that affects the growth and development of crops. Salt stress in various regions adversely affects sorghum ( Sorghum bicolor L.) production because saline soil declines or even stops the physiological processes. This study was conducted to find out the effects of ( Parthenium hysterophorus ) biochar (0%, 4%, 8%) on the morpho-physiological traits and biochemical characteristics of sorghum plants to enhance their ability to tolerate salt. Two sorghum varieties JS-2002 (V1) and Sandal-bar (V2) were subjected to NaCl salinity (0mM, 100mM, and 150mM) three weeks after germination. The design of the experiment was a completely randomized design (CRD), having 3 replicates that were arranged in a factorial structure. Salinity significantly reduced morpho-physiological and biochemical attributes. Biochar significantly increased the production of proline (Pro) and glycine betaine (GB) in both varieties. The production of ROS hydrogen peroxide (H 2 O 2 ) decreased by 58% in V1 and 64% in V2, along with the reduction in malondialdehyde (MDA), a lipid peroxidation marker, by 63% in V1 and 52% in V2 at 8% biochar and 150mM salinity. Moreover, biochar application also increased peroxidase (POD) 50.9% in V1 and 53% in V2, superoxide dismutase (SOD) 31.3% in V1 and 36.9% in V2, catalase (CAT) 22.6% in V1 and 21.8% in V2, and ascorbate peroxidase (APX) 34.45% in V1 and 41.93% in V2 at 8% biochar and 150mM salinity. Salt stress also led to an increase in Na + and a decrease in K + and Ca 2+ . However, biochar application enhanced K + and Ca 2+ in salt-stressed plants. The levels of secondary metabolites, i.e., anthocyanin (Ant), enhanced by biochar 53.72% in V1 and 74% in V2, flavonoids (Flv) 47.59% in V1 and 69.73% in V2, and total phenolics (TP) 103.26% in V1 and 102.57% in V2 under 150mM salinity and 8% biochar. These findings suggest that applying biochar in a suitable amount could mitigate the adverse effects of salt stress and increase antioxidant enzymes that mitigate the negative effects of salinity, but excess biochar application may have negative influences on seedling growth.