Abstract:

【Objective】The objective of this study was to investigate the growth changes and osmotic adjustment of perennial herbaceous Iris plant (Iris lactea Pall. var. chinensis (Fisch.)Koidz.)under interactions of soil moisture and salinity, and to provide a scientific basis for cultivation and utilization of I. lactea var. chinensis.【Method】I. lactea var. chinensis seedlings under sand culture condition were treated with the 15 cross combinations of different NaCl concentrations of 0(CK), 0.5, 1, 1.5, and 2% and three soil moisture levels of 100, 65, and 45%(of field capacity). After 8 d treatment, the contents of inorganic ions, proline (Pro) and soluble sugar (SS) in shoots were determined, respectively, and their contributions to the osmotic potential were calculated.【Result】The optimal growth condition for I. lactea var. chinensis was high soil moisture and low salinity, 1.5%-2% NaCl caused a significant decrease in shoot biomass, while decrease in soil moisture from 100% of field capacity to 65% resulted in a 14% increase in shoot biomass at 2% NaCl. At 45% of field capacity, biomass was not significantly different between 0.5% and 1% NaCl. Contents of Na+, Cl- and Pro in shoots significantly increased with the decrease of moisture levels of soil. More inorganic ions played an important role in osmotic adjustment with soil moisture decreasing, estimated contribution of inorganic ions to osmotic potential was 90% at 1.5% NaCl combined with 45% of field capacity. It had no significant effect on estimated contribution of Pro and SS to osmotic potential.【Conclusion】The growth of I. lactea var. chinensis at high salinity was increased by moderate moisture level, and the drought tolerance of I. lactea var. chinensis was improved by moderate salinity. As soil moisture decreased, inorganic ions played a more important role in osmotic adjustment, more inorganic ions but less organic osmoticum were involved in osmotic adjustment in leaves of I. lactea var. chinensis.