Investigation of Na+, K+ and Ca2+ distribution and ion fluxes of the halophyte Chinese iris under NaCl stress by non-invasive micro-test techniques

Chinese iris (Iris lactea Pall. var. chinensis (Fisch) Koidz.) is a high salt tolerant green vegetation. The objective of this study was to probe the ionic balance mechanism of iris under salt stress. iris were cultivated in hydroponic system supplemented with Hogland nutrition solution under greenhouse condition. After 20 d of cultivation. Iris were treated with 0, 70, 140, 210 and 280 mmol L- 1 NaCl. The growth status, ion content and ion fluxes of roots and leaves were measured after 10 d of NaCl treatment. Chose 0, 210 mmol L- 1 NaCl treatment to detect Na+, K+, H+, Ca2+ net fluxes by non-invasive micro-test technique (NMT). Our major results are as follows: 1) iris growth were impaired under NaCl stress, the length, fresh and dry weight were significantly reduced; 2) iris has the ability to accumulate Na+ in roots and increase transportation of K+, Ca2+ to leaves; 3)The efflux of Na+, K+ increased about 2.5, 85.4 times respectively under 210 mmol L- 1 NaCl stress, and the efflux of H+ decreased 76.6% as compared to control. The roots Ca2+ showed a net efflux under normal condition and a net influx under stress condition. The leaves displayed a significant increase of Na+ influx and decrease of K+ efflux.