Effects of Exegenous Glycine Betaine Treatments on Growth and Some Physiological Characteristics of Tomato under Salt Stress Condition

The effects of the exogenous foliar application of glycine betaine (gb) with different doses (0, 5, 10 and 20 mm) on plant growth, chlorophyll content, stomatal conductance, phenolic and proline contents in tomato grown under salt stress were evaluated. tomato plants (lycopersicon esculentum mill.) were imposed to salinity stress for 2 months with 75 mm nacl. salt stress reduced the growth, chlorophyll reading values and stomatal conductance in tomato. gb application decreased the inhibation of salt stress on tomato plant growth, and increased stomatal conductivity and chlorophyll content. the effective dose of gb was 10 mm to increase tolerance against salt stress. plant height significantly increased in 5, 10 and 20 mm gb treatments by 2.2, 13.1 and 18.9%, respectively compared to the control. 5 and 10 mm gb treatments significantly increased chlorophyll reading values (51.18 and 53.44, respectively) compared with control (48.92). 10 mm gb exhibited a rapid increase in stomatal conductivity by 11.3% compared with control. moreover, 10 mm gb showed an increase in proline content by 53.4% compared with control. according to results of our study, it can be suggested that exogenous gb treatments could mitigate the deleterious effects of salt stress in tomato.