Effect of saline water irrigation on growth and physiological responses of three rose rootstocks

Salt-tolerant landscape plants are needed for arid and semiarid regions where the supply of quality water is limited and soil salinization often occurs. This study evaluated growth, chloride (Cl) and sodium (Na) uptake, relative chlorophyll content, and chlorophyll fluorescence of three rose rootstocks [Rosa x fortuniana Lindl., R. multiflora Thunb., and R. odorata (Andr.) Sweet] irrigated with saline solutions at 1.6 (control), 3.0, 6.0, or 9.0 dS.m(-1) electrical conductivity in a greenhouse. After 15 weeks, most plants in 9.0 dS.m(-1) treatment died regardless of rootstock. Significant growth reduction was observed in all rootstocks at 6.0 dS.m(-1) compared with the control and 3.0 dS.m(-1), but the reduction in R. x fortuniana was smaller than in the other two rootstocks. The visual scores of R. multiflora at 3.0 and 6.0 dS.m(-1) were slightly lower than those of the other rootstocks. Rosa odorata had the highest shoot Na concentration followed by R. multiflora; however, R. multiflora had the highest root Na concentration followed by R. odorata. All rootstocks had higher CI accumulation in all plant parts at elevated salinities, and no substantial differences in CI concentrations in all plant parts existed among the rootstocks, except for leaf CI concentration in R. multiflora, which was higher than those in the other two rootstocks. The elevated salinities of irrigation water reduced the relative chlorophyll concentration, measured as leaf SPAD readings, and maximal photochemical efficiency of photosystem II (PSII) and minimal fluorescence (F-o)/maximum fluorescence (F-v/F-m), but the largest reduction in F-v/F-m was only 2.4%. Based on growth and visual quality, R. x fortuniana was relatively more salt-tolerant than the other two rootstocks and R. odorata was slightly more salt-tolerant than R. multiflora.