Present study prescribed the potential of varyingly devised osmotic constrains on germination and growth of Parthenium hysterophorus, an alien highly invasive weed species. The effects of differential salinity regimes of three selected salts viz. NaCl, KCl, and MgSO4 were evaluated on germination and growth in lab as well as field trials. Different concentrations of test salts for lab experiments were 10, 20, 30, 40 and 500, 750, 1000, 1250 mM for field experiment.Germination fresh and dry weights of shoot and root as well as leaf area in all treatments were significantly reduced. Likewise, status of mycorrhizal colonization was also found higher in control against all saline conditions. Decline of 86% was observed in against maximum concentrations.The salinity threshold of P. hysterophorus (L.) was estimated up to 0.75 M and mortality recorded at higher salinity regimes. This book is helpful to botanists, agriculturalists, mycologists, weed scientists and environmental scientists.