Study On Seed Germination And Seedling Salt Tolerance Of Elaeagnus Angustifolia From Different Provenances

The aggravation of soil salinization poses great threats to the ecological securityand agriculture sustainability. In recent years, efforts have been made to improvesaline soil and the screening and cultivation of salt-tolerant plants has been proved tobe an effective method. The Yellow River Delta in Shandong Province is seriouslysalinized, with very simple landscape ecological system due to the less garden speciessuitable for cultivation. Elaeagnus angustifolia from different provenances arescreened as candidate green-trees planted in this area due to the characteristics per sesuch as strong vitality, resistance to drought, wind, salinity.E. angustifolia is deciduous tree belonging to Elaeagnaceae Elaeagus, which iswidely distributed in Northwest areas in China. It has reported that E. angustifoliafrom different regions differed in salt-tolerance. In the present study, we screened E.angustifolia with different provenances, selected those with high salt-tolerance andexamined their salt tolerance mechanism in order to provide some theoretical basis forthe plant introduction program in the Yellow River Delta. Main results of this researchwere summarized as following:1. The collection of the seeds: We collected E. angustifolia from ten areas inXinjiang, Neimeng, Gansu and Ningxia provinces.2. Examination on Germination: The germination rate, germination force andgermination index of E. angustifolia seeds from all ten provenances were significantlyreduced with the NaCl concentration increased. And no obvious differences of theseindexes were observed under low salt concentration in comparison with control, butunder higher salt concentration, all the indexes were significantly reduced. Seedstolerance ability from different provenances were also assessed by membershipfunction and from strong to weak, the seeds tolerance ability was: Shiyanghe> Minqin> Xinjiang> Pingluo> Turpan> Jinchang> Linhe> Gulang> Yinchuan>Zhongning.3. Seedling screening: The relative height, relative fresh weight and relative dryweight were significantly reduced with the NaCl concentration increased, except thatTurpan and Minqin provenances reached the maximum at0.3%NaCl concentration.When assessed by membership function, seedlings tolerance ability of ten differentprovenances (from strong to weak) was: Minqin> Pingluo> Yinchuan> Shiyanghe>Turpan> Xinjiang> Linhe> Gulang> Jinchang> Zhongning.4. Taking the germination examination and the seedling screening resultstogether, we chose Pingluo and Shiyanghe as the salt-tolerant provenances,Zhongning as the salt-sensitive provenance, we further studied the salt tolerancemechanism of E. angustifolia.The results showed that: with the increase of NaCl concentration, the Tr, Gs andPn of three provenances rose first and then decreased gradually compared with control,but there was continuous declination in Ci. Under NaCl stress, no significant changescould be observed on fluorescence parameters (Fv/Fm, ΦPSⅡ) and chlorophyllcontent compared with control. The content of MDA and proline in E. angustifoliaseedling leaves increased more obviously as NaCl concentration increased, and theZhongning provenance had the biggest increase, followed by Shiyanghe. Solublesugar content increased insignificantly compared with control with the increase ofNaCl concentration. The content of soluble protein had increased first but reducedunder increasing NaCl stress. Under NaCl concentration the Na+content increased inroots and leaves, but the K+content of reduced. Treated with NaCl, the value ofNa+/K+increased with the biggest value detected in Zhongning, followed byShiyanghe.5. Comparison of salt-tolerant and salt-sensitive E. angustifolia.: the inhibitioncaused by NaCl was more serious in salt-sensitive provenance than that insalt-tolerant provenance. The contents of chlorophyll and photosynthetic parametersin Zhongning provenance were lower than that in the salt-tolerant. MDA contentsexperienced the biggest increase in Zhongning provenance, leading to the damage to the cell membrane integrity. Under NaCl stress, proline, a major substance for cellularosmotic pressure adjustment, increased more in salt-sensitive provenance than that inthe salt-tolerant. Similarly, Na+/K+had the maximum increase in Zhongning underNaCl treatment. Meanwhile, the salt-tolerance E. angustifolia provenance couldobstruct Na+accumulation in roots more effectively, reducing Na+content in leaves,and thus could better maintain the cytoplasm Na+/K+balance. This also shows that themode of salt tolerance in E. angustifolia is salt-exclusion.