Investigating the effects of Glycine betaine on growth and flower yield of Damask Rose under salinity stress

In order to investigate the effect of glycine betaine (GB) on some growth and yield traits of Damask Rose, an experiment was conducted as factorial based on a completely randomized design with 3 replications at Research Greenhouse of National Salinity Research Center during 2018-19 growing season. The treatments were four levels of salinity: 2 (control), 5, 8 and 11 dS/m and three levels of GB: without application (control), spraying with 50 mM and 100 mM concentrations. The results showed that the main effect of salinity stress was significant on all studied characteristics, except branch number per plant and petal number. Moreover, the main effect of GB was significant on all measured traits, except branch number per plant, petal number, height and petal weight/flower weight ratio. The most flower number per plant, flower yield and essential oil yield were observed in stressed plants at 2, 5 and 8 dS/m salinity, had more 7.5 flower, 29.5 g flower weight per plant and 6 mg essential oil per plant than 11 dS/m, respectively. The interaction results between salinity stress and foliar application of glycine betaine showed that the treated plants with 2 dS/m and 100mM GB had the highest height (71 cm) and the treated plants with 10 dS/m and without application of GB had the lowest height (40 cm). In general, using 50 mM GB and without salinity stress caused the highest Damask Rose weight.