Synergistic Effects of Endophytic Bacteria and Biochar on Morphophysiological Traits, Ionic Homeostasis and Grain Quality of Sorghum under Saline Soil Conditions

HistorySalinity is a major constraint limiting crop productivity in suboptimal lands, necessitating the development of sustainable strategies to improve plant performance.This study evaluated the combined effects of endophytic bacteria and biochar on the morphophysiological traits, ionic homeostasis, and grain quality of sweet sorghum under saline soil conditions (electrical conductivity 5 dS m⁻¹) in North Sumatra, Indonesia.The experiment was conducted using a factorial randomized block design with two factors, namely endophytic bacteria (0, 5, 10, and 15 mL polybag⁻¹) and biochar (80 and 120 g polybag⁻¹).Unlike previous studies that mainly examined either microbial inoculants or biochar separately, this study provides an integrated evaluation of their synergistic effects across morphological, physiological, anatomical, ionic, and grain biochemical responses under saline conditions.The combined application significantly enhanced plant growth, yield components, chlorophyll content, nutrient uptake, and grain nutritional quality while reducing Na accumulation and improving the K⁺/Na⁺ ratio, indicating better ionic homeostasis.These improvements were accompanied by increased stomatal density, optimized cuticle thickness, and enhanced carbohydrate, protein, and amylose contents, demonstrating coordinated structural and metabolic adaptation to salinity stress.The synergistic interaction between endophytic bacteria and biochar effectively mitigated the adverse effects of salinity by improving physiological function, nutrient balance, and grain quality.These findings highlight the potential of integrating endophytic bacterial inoculants with biochar as a sustainable management strategy for enhancing sweet sorghum productivity on salt-affected soils and provide a promising approach for climate-resilient agriculture.