Acidified Organic Amendment and Endophyte Bacillus sp. MN‐54 Vitalized the Physico‐Chemical, Antioxidants and Nutritional Status via Enhanced Endophytic Colonisation in Brassica napus Under Calcareous Saline‐Sodic Soil

Soil salinity poses significant ecological threats to global food security, necessitating effective remediation strategies. Elemental sulphur (S o ) based amendments efficiently decrease soil salinity and pH, enhancing soil properties and crop yield. However, the widespread adoption of S o in managing calcareous saline soils remain limited due to the lack of standardised application methods for different soil types and environmental conditions. This pot experiment was conducted to evaluate the effects of acidified manure (AM) applied at 1% and 2%, either alone or in combination with a plant growth‐promoting endophyte (PGPE), Bacillus sp. MN‐54, on canola growth and salinity tolerance. The study included three soil salinity levels: non‐saline soil (EC = 1.45 dS m −1 ), moderately saline soil (EC = 5 dS m −1 ) and highly saline soil (EC = 10 dS m −1 ). Treatments were applied to pots filled with 8 kg of soil, and plants were grown under natural conditions for 90 days. Results showed that salinity negatively affected canola growth, while combined AM and MN‐54 applications significantly improved dry biomass of the plant root (112% and 85%) and shoot (181% and 330%) at EC 5 and 10 dS m −1 , respectively. The same treatment reduced soil pH by up to 18%, EC by 64% and Na + by 57%, while increasing Ca 2+ and by up to 120% and 158%, respectively, while enhancing photosynthetic rate by 80% and 170% and improving K + /Na + ratio by 120% and 173%, under 5 dS m −1 and 10 dS m −1 conditions, respectively. Improved crop growth under saline stress highlighted the potential of AM and MN‐54 as a sustainable approach for enhancing salinity tolerance, promoting soil health and increasing crop productivity. This highlighted their practical implementation to enhance crop resilience and productivity in salt‐affected agricultural lands.