Foliar Spray of Thiourea Enhances Salt Tolerance and Improves Biochemical Induced Physiological Responses in Gerbera jamesonii

Salinity is a significant abiotic stress factor for ornamental plants cultivated in greenhouses, as they are supplied with fertilizers over a long period of time. It causes drastic yield losses in com-mercially important ornamentals such as Gerbera jamesonii, whose cut flowers rank fifth in the global flower trade. In the current study, pretreatment of G. jamesonii plants (white and yellow flowering varieties) with optimum concentrations of thiourea (1.0 mM, 5.0 mM & 10.0 mM) in-duced plant salt-tolerance. Gerberas pretreated with thiourea (5.0 mM), when exposed to NaCl (200mM), showed no signs of plant stress or phenotypic abnormalities, as seen in gerberas ex-posed to NaCl without thiourea pretreatment. Moreover, thiourea application significantly pro-moted plant growth as evidenced by increases in fresh and dry leaf weight, relative water con-tent, total protein content, free proline content, and chlorophyll. A decrease in H2O2 and MDA content and an increase in antioxidant enzymes superoxide dismutase, catalase, ascorbate perox-idase, glutathione reductase, and peroxidase activity indicate minimal cellular damage in gerberas treated with thiourea. Thus, spraying leaves with thiourea (5.0 mM) could help gerbera plants overcome the deleterious effects of salt stress during repeated fertilization in nethouses. In addi-tion to alleviating salt stress, thiourea can also be used as a biofertilizer. This could also be ex-tended to other ornamental species to promote sustainable development of the floriculture indus-try.