The Effects Of Salinity And Waterlogging Interaction On Physiological Characteristics Of Elaeagnus Moorcroftii Wall.Ex Schlecht Seedlings

Recent years, salinization has become a serious problem, which restricts the development of agriculture, forestry and animal husbandry around the world. At the same time, there are many other factors which inhibit the growth of plants, such as drought, waterlogging, low-temperature and so on. Among the factors, waterlogging also lead to the secondary salinization of land. On the salinization land, plants sometimes suffered from two or more stresses, so screening plants what is resistant to salt and waterlogging, then introducing them to the saline regions can improve the ecological environment.Elaeagnus moorcroftii Wall. ex Schlecht(Oleaster, also called Russian olive) is a deciduous shrub or a small tree. It is ideal plant of improving saline-alkali land because of its good resistance to salinity, drought and barren. E. moorcroftii is planted in the arid region of northwest China, so it has drought resistance. However, whether E. moorcroftii can live in waterlogging has not been reported. In this paper, we planted E. moorcroftii with NaCl(0%, 0.6%, and 0.8%), waterlogging, NaCl(0%, 0.6%, and 0.8%) and waterlogging, then measured the related indicators of E. moorcroftii seedlings from plant morphology, photosynthesis, hormones and physiological and biochemical aspects. After two weeks of waterlogging, the waterlogging stress was removed(that is treated only in 0% NaCl, 0.6% NaCl, and 0.8% NaCl) for two weeks and then measured the growth and photosynthesis parameters of E. moorcroftii seedlings. The results are as follows.1. Morphologyunder the treatment of NaCl, plant height, diameter and biomass of seedlings significantly reduced, area and perimeter of leaves gradually decreased as the NaCl concentration increasing. Waterlogging significantly decreased the plant height and biomass of seedlings, especially for the roots biomass. under waterlogging, the area and perimeter of leaves siginifiantly decreased, and the old leaves became yellow. under waterlogging, the diameter and porosity of root increased significantly, and new roots root generated from the flooded part of seedlings which is conducive to root respiration. These characteristics shown that E. moorcroftii has adaptability to waterlogging. 0.6% NaCl and waterlogging interaction made smaller damage to E. moorcroftii than waterlogging, 0.8% NaCl and waterlogging interaction.2. Photosynthesisunder the treatment of NaCl, as the increasing of NaCl concentration, chlorophyll content of E. moorcroftii leaves reduced, Pn, Tr and Gs declined significantly. Waterlogging inhibited the Pn of E. moorcroftii very significantly, meanwhile, chlorophyll content of leaf, Tr,Gs, Fv/Fm, ?PS II and qP also declined, but they reduced less than Pn. Compared with waterlogging, 0.8% NaCl and waterlogging interaction, photosynthesis of E. moorcroftii seedlings were higher under the treatment of 0.6% NaCl and waterlogging interaction. The conclusion can be made from all the data is that waterlogging inhibit significantly the photosynthesis of E. moorcroftii seedlings, and the reasons are not the stomatal factors but the structure damage the chloroplast and the decreased enzyme activity. But the harm to E. moorcroftii seedlings of salinity and waterlogging interaction is less than waterlogging.3. HormonesWith the NaCl concentration increasing, IAA, GA3, ZR and BR in leaves reduced, and ABA increased. At the same time, the change of hormones in roots was consistent with leaves. Waterlogging increased the content of IAA, BR and ABA in the leaves, GA3 and ZR content in the roots. Waterlogging also reduced IAA, BR and ABA content in the roots. In this experiment, NaCl made impact on hormone content of E. moorcroftii seedlings more significant than waterlogging, and NaCl made impact on leaves more significant than roots.4. Physiological and biochemicalWith the increasing of NaCl concentration, Na+ content in leaves and roots siginificantly increased and K+ content reduced. Proline, soluble sugar and organic acid in leaves siginificantly increased, which lead to the lower osmotic potential of cell. With the increasing NaCl concentration, the damage extent of cell membrane gradually increased. under the treatment of waterlogging, Na+ content in leaves and roots increased, and the changes in leaves is more obvious. Meanwhile, K+ content reduced in leaves and roots. The reducing of organic solutes content and increasing MDA of leaves both shown cell was damaged heavily under waterlogging. Compared with the same NaCl treatment, the treatment of NaCl and waterlogging interaction significantly,increased organic solutes content of E. moorcroftii seedlings and reduced osmotic potential of cell. MDA content had no significant difference under NaCl and waterlogging. The results showed that E. moorcroftii seedlings under NaCl and waterlogging interaction growed better than seedlings under waterlogging, and that is due to the accumulation of organic material in plants.5. Restoring experimentAfter removing waterlogging, E. moorcroftii seedlings without NaCl treatment showed better resilience than that of NaCl treatment. Plant height and biomass had no significant difference under two different treatment. Chlorophyll content in leaves and Pn of E. moorcroftii seedlings significantly increased after removing waterlogging and were higher in leaves of seedling treated without NaCl.