Exploring the phytostabilization potential of ryegrass (Lolium perenne L.) upon synergistic application of Cd-tolerant Pseudomonas fluorescens 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 P. fluorescens 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 P. fluorescens 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 P. fluorescens 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.