The beneficial effect of salicylic acid on rose plants exposed to iso-osmotic stress

Abstract: Effect of 0.01M salicylic acid treatment on two rose plant cultivars (?Red Berlin? and ?Red Horizon?) exposed to 0.2M NaCl or 0.35M D-Mannitol iso-osmotic stress (-1,05MPa) was studied. After five days of stress, the salicylic acid treatment strongly increased the proline content in leaves up to 28 times compared to control. It did not affect the soluble sugars content in ?Red Berlin?, but decreased it below the control levels in ?Red Horizon?. The plant response to salicylic acid application varied and was dependent upon the cultivar and the iso-osmotic agent. Thus, the salicylic acid had a beneficial effect on plants under NaCl stress and caused a slight increase in chlorophyll content and a significant increase in the quantum yield of photosystem PII in rose plants under Mannitol stress (Fv/Fm ratio about 0.72). It also increased leaf fresh/dry weight ratio of stressed plants (81% in ?Red Berlin?), while it significantly reduced electrolyte leakage of stressed leaves.