Effect of salicylic acid on the growth and biomass partitioning in water-stressed radish plants

Given the potential of salicylic acid (SA) in mitigating stress in plants, this study evaluated the effect of different concentrations of SA on production, biomass allocation, and chlorophyll index in radish plants ( Raphanus sativus L.) grown under water deficit. For this purpose, plants were irrigated at 80% and 20% of field capacity (FC), with SA applied at the concentrations of 0 (control), 100 µM, 1 mM, and 10 mM. Chlorophyll a and b indices, and biomass partitioning parameters were determined. Water deficit reduced biomass accumulation in the aerial part and root of control and 1 mM SA-treated plants, whereas under 100 µM SA treatment, the root fresh mass was higher when grown at 20% FC than at 80% FC. The 10 mM SA treatment led to the reduction of the biomass at both irrigation levels. Control and 1 mM SA-treated plants showed higher leaf mass fraction and lower root mass fraction under water deficit, compared to well-irrigated plants. In contrast, among the plants treated with 100 µM SA, those irrigated at 20% FC allocated more biomass to the root and less to the leaves than those irrigated at 80% FC. There were no effects of irrigation level and concentration of SA on the chlorophyll level. In summary, 100 µM SA application was effective in mitigating the effects of water deficit on biomass accumulation and partitioning in radish plants.