Evaluating the hidden potential of deashed biochar in mitigating salinity stress for cultivation of fenugreek

Abstract Soil salinity, the second most prominent cause of land degradation after soil erosion, has posed a persistent challenge to agriculture. Currently, approximately 1 billion hectares of Earth's land surface, equivalent to 7%, are affected by salinity. While biochar has proven effective in mitigating salinity stress, the specific role of deashed biochar in salinity mitigation has not been thoroughly explored. Therefore, this study was conducted to investigate the impact of four levels of deashed biochar (0%, 0.4%, 0.8%, and 1.2%) on the growth and physiological attributes of Fenugreek under both non-saline conditions (2.54 dS/m EC) and salinity stress conditions (5.46 dS/m EC). The results revealed a notable enhancement in various parameters under salinity stress. Compared to the control, the application of 1.20% deashed biochar led to a significant increase in shoot fresh weight (30.82%), root fresh weight (13.06%), shoot dry weight (17.43%), root dry weight (33.44%), shoot length (23.09%), and root length (52.39%) under salinity stress. Furthermore, improvements in internal CO2 concentration (9.91%), stomatal conductance (15.49%), photosynthetic rate (25.50%), and transpiration rate (10.46%) were observed, validating the efficacy of 1.20% deashed biochar in alleviating salinity stress. The study also demonstrated a significant decrease in the activities of oxidative stress markers such as peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), electrolyte leakage, and malondialdehyde (MDA). Simultaneously, there was an increase in the concentrations of essential nutrients, namely nitrogen (N), phosphorus (P), and potassium (K), in both shoot and root tissues. These findings collectively suggest that deashed biochar, particularly at a concentration of 1.20%, is recommended for achieving enhanced crop production under conditions of salinity stress.