Biochar is a sort of organic fertilizer derived from the pyrolysis of plant residuals and crop waste and is recommended for improving soil fertility and modifying saline soils. In this regard, the effect of biochar on moderating the effects of salinity stress on growth and some physiological traits Catharanthus roseus L. was explored in a factorial experiment based on a randomized complete block design with two treatments including salinity stress (0, 1000, 2000, and 3000 mg/kg NaCl) and biochar (0, 2, and 4%) in 3 replications, 36 plots, and 6 plants per plot. The study was conducted in pots in the spring of 2021. The results showed that salinity negatively influenced all studied morphological traits and relative water content (RWC) whereas biochar, especially at the rate of 2%, helped their preservation and improvement. With increasing the salinity level, the proline content and total soluble solids (TSS) increased versus the control. The highest level of proline (346.48 mmol/kg FW) and TSS (1.42°Brix) were recorded for NaCl3000 mg/kg × biochar0%. A decline was recorded in malondialdehyde (MDA) with the application of 2% biochar at all four NaCl levels, but biochar at the rate of 4% failed to alleviate salinity effects at the highest level of NaCl (3000 mg/kg) and this treatment exhibited the highest MDA level. The highest activities of peroxidase (POD) (1.56 IU/g FW/min) and ascorbate peroxidase (APX) (9.40 IU/g FW/min) were observed in the treatment of NaCl1000 mg/kg × biochar2%. With increasing the NaCl level (2000 and 3000 mg/kg), POD and APX activities decreased, which was accompanied by an increased accumulation of MDA. Based on the results, it can be concluded that by applying 2% biochar at the salinity level of 1000 or 2000 mg/kg, periwinkle plants with acceptable morphophysiological traits can be produced. پرونده مقاله