Synergistic application of nano-silicon and Streptomyces albogriseolus enhances maize salinity tolerance by modifying soil silicon fractions and ionic homeostasis

Salinity adversely affects the physiological and biochemical processes in maize (Zea mays L.), leading to significant yield losses. This study aimed to evaluate the combined effects of nano-silicon (nano-Si) and halotolerant Streptomyces albogriseolus (S. albogriseolus) on the morphological, physiological, biochemical characteristics of maize, and Si fractions under salinity stress. A factorial pot experiment was conducted using three salinity levels (1.4 (control), 5, and 8 dS m−1), four nano-Si concentrations (0, 100, 200, and 400 mg kg−1), and inoculation with or without S. albogriseolus. Both nano-Si and S. albogriseolus improved plant performance; however, their combined application produced the strongest mitigation effect. Under severe salinity, co-application of nano-Si and S. albogriseolus increased shoot dry weight (55%), root dry weight (78%), shoot length (51%), and root length (82%), reduced malondialdehyde (MDA) (35%), enhanced catalase (CAT) activity, reduced Na accumulation (19%), and restored ionic homeostasis N (41%), P (25%), K (22%), and Si (28%), thereby improving the K/Na ratio. This treatment also enhanced the plant-available soil Si pools (soluble and exchangeable fractions). This integrated approach offers a sustainable and environmentally friendly strategy for enhancing maize resilience and productivity under saline stress.