Serotonin improves plant growth, foliar functions and antioxidant defence system in Ethiopian mustard (Brassica carinata A. Br.)

Every year, high salinity reduces agricultural crop yields by a substantial amount due to osmotic and ionic impacts that prevent plants from absorbing the required water and promote the hyperaccumulation of ions, which enter the transpiration stream and injure plant cells. Thus, in general, the effects of salinity stress on plant physio-chemicals functions are well known, but little has been explored on how serotonin combats abiotic stress in Ethiopian mustard (Brassica carinata). In this study, the effect of serotonin (SR; 200 µmol L−1) on Ethiopian mustard under salt stress (SS; 0, 50, 100 and 150 mM) was examined. Results exhibited that all SS levels tested in this trial were able to offer a significant reduction of plant growth parameters, chlorophyll contents, gas exchange, water use efficiency, fv/fm and nitrate reductase activity (NR) and increased the antioxidants and proline contents. However, the foliar application of SR significantly ameliorated the influence of all SS levels by improving gas exchange parameters, chlorophyll contents, PSll photochemical efficiency, antioxidant activities, proline, NR, water use efficiency and growth parameters. Based on these results, it is recommended that SR application is useful to uplift the growth, yield and physio-chemical mechanisms of Ethiopian mustard. Furthermore, the SR application can be carried out on various traditional crops under different climate conditions for sustainable agriculture production.