Soybean plants (Glycine max L. cv. Buchanan) were subjected to one of three levels of salinity preteatment (with electrical conductivities of 0.7, 4.4 and 6.5 dS m−1) and then exposed to one of three concentrations of SO2 (1, 145 and 300 bl l −1 for 5 h d−1), or vice versa. Each stress episode lasted 3 weeks. Both salinity and SO2 deecreased leaf area, root and shoot dry weight and the fresh weight of root nodules. SO2 induced an increase in the shoot: root ratio and leaf chlorophyll concentrations. Low salinity pretreatment protected plant growth from SO2 injury, probably by decreasing SO2 uptake by increasing stomatal resistance. However, high salinity-treated plants, despite also showing stomatal closure, were severely injured by subsequent SO2 exposure. Prior exposure to SO2 caused plants to become more vulnerable to salt injury. Plants pretreated with high SO2 were killed after 12 days of high salt stress. These data suggest that the compensatory mechanisms and predisposition characteristics of salinity and SO2 largely depend upon the stress levels used
To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.