Research On The Physiological-Ecological Mechanism Of Salt-alkaline Tolerance In Kochia Sieversiana

These experiments were conducted to investigate the effects of single salt and mixed-salton the seed germination and seedlings growth in Kochia sieversiana. In general: effects ofalkalic salts were more serious than those of neutral salts. With increasing of alkalic saltsconcentrations, effects of alkalic salts on seeds and seedlings were more severe. We alsoinvestigated growth regulation of four kinds of communities in different season.Germination percentage, growth of hypocotyl and radicle, germination index and vitalindex were all stimulated under the low saline concentration. With increasing of saltconcentration, germination percentage, germination index and vital index were decreased.Under the same condition, growth of hypocotyl and radicle were inhibited. Effect of salt onradicle growth was more serious than that of hypocotyls. Na⁺ concentration were increased,whereas K⁺,Ca²⁺,Mg²⁺ concentrations were increased with increasing of single salt. Ratio ofNa⁺ to K⁺ in K. sieversiana root was higher than that of shoot. Although Na⁺ is a kind ofessential element of halophyte, Na⁺ concentration in plant tissue must be restrained in specialconcentration. Otherwise,higher Na⁺ concentration would disturb other cation metabolism.Kochia sieversiana can absorb Na⁺ effectively and prevent excessive Na⁺ from transporting tothe cotyledon. It may be the reason that K sieversiana can survive in high salt concentration.The organic acid accumulations in K. sieversiana seedlings were stimulated in the salt(neutral salt and alkalic salt) stress. Under the low concentration treatment, oxalic acidaccumulation was dominant at the K. sieversiana seedlings. Malic acid concentration wasincreased with increasing the stress, even if its concentration was higher than that of oxalicacid. The concentrations of other organic acids were in the order of succinic acid>tartaric acidand citric acid concentration was the lowest. The organic acid distribution was similar tocation distribution. In other words, the concentrations of organic acid and cation in K.sieversiana root were higher than those of shoot.The above findings can now explain thatorganic acids combined with cations can decrease ion toxicity. Accumulations of organicacids in alkalic salts treatment were higher than those in neutral salt treatment. So weconcluded that it was important for K. sieversiana seedlings to accumulate organic acid andmaintain the stabilization of internal environment.Based on the variation of proline concentration and antioxidase activity, we should makea comparison between the four-week plants and seedlings. Proline concentration andantioxidase activity of four-week plants were higher than those of seedlings. So, four-weekplants were less sensitive than seedlings under the extreme environment. Matter accumulationand energy metabolism of different tissues in three phenotypes of K. sieversiana werechanged regularly. In the same tissues, the concentrations of Na+ and proline were decreasedwith increasing the height of different phenotypes. The concentrations of K+, Ca2+, Mg2+ andcalorific value were increased with increasing the height of different phenotypes. The prolineconcentrations of leaves were higher than those of stems in the same phenotypes. Na+concentrations of leaves were the highest among all the tissues, while K+ Ca2+ Mg2+concentrations of seeds were the highest among all the tissues. The calorific values were inthe order of roots> stems> seeds> leaves. The results showed that the accumulations ofinorganic ions and the synthesis of osmoregulation matters were induced by salt in the field.The energy distribution was changed under the salt stress. The higher the stress strength ofenvironment was, the higher the energy consumption of seedling was. So, the differentphenotypes were induced under the extreme environment. We also investigated therelationship between the seasonal growth of different communities and soil physicochemicalproperties. The height and the biomass of different communities emerged the grand period ofgrowth with variation of growth season. From the datum of biomass of different communities,conductivity and pH of soils, we concluded that Suaeda salsa was one of the most tolerancepastures. The next was K. sieversiana. Aneurolepidium chinense was more sensitive than K.sieversiana and Suaeda salsa.