Exploring the phytostabilization potential of ryegrass ( <i>Lolium perenne</i> L.) upon synergistic application of Cd-tolerant <i>Pseudomonas fluorescens</i> and organic amendments

Soil Cd contamination limits plant productivity by affecting their key functions and reducing yields. In-situ immobilization of heavy metals (HMs) can achieve 'green' and 'sustainable' ways of HM remediation owing to its lower life cycle environmental footprints. This study explored the effects of Cd-resistant <i>P. fluorescens</i> and OAs such as rice straw, wheat straw and cow dung (1% w/w) on the Cd tolerance of ryegrass under Cd contamination (2.2 mg kg^-1). In our findings, Cd exposure reduced plant height (22%), root length (38%), chlorophyll 'a' and 'b' (36 and 38%), and relative water content (32%) in uninoculated plants. However, combined use of <i>P. fluorescens</i> and OAs mitigated these effects by immobilizing Cd in soil, with a 56% increase in residual Cd and higher Cd retention in roots and shoots (77 and 87%). Co-application enhanced plant height (96%), root length (158%), chlorophyll content (90 and 98%), relative water content (168%), flavonoids and phenols (151 and 68%) and NPK uptake (104, 73 and 71%) as compared to uninoculated control. Integration of <i>P. fluorescens</i> and OAs not only reduced Cd uptake but also improved growth and yield. Thus, this approach mitigates Cd stress in ryegrass, improving growth and physiology by reducing Cd uptake.