Study On The Salinity Adaptability Of Desert Plant Lycium Ruthenicum

Soil salinization is one of the main types of desertification.Lycium ruthenicumMurr.is widely distributed in the desert area of northwest China,showing strong adaptability to salt soil.The study on the saline adaptability of Lycium ruthenicum has great significance for the restoration of vegetation and the management of ecological environment in desert area.In this study,desert plant Lycium ruthenicum was selected,the population distribution pattern,community composition and structure were investigated from 8 natural communities of dominant species of desert plant Lycium ruthenicum at the lower reaches of Heihe River in Ejina Area,the leaf functional traits?TWC,RWC,LDMC,SLA,SLV,LT,Suc,LD,C,N,P,C / N,C / P,N / P?were determined,the relationship of community deversity and soil salt,soil salinity,p H,the dissociation characteristics of intraspecific traits,the relationship of traits,and relationship of traits and soil salt were analyzed;Single salt?NaCl?and complex salinity-alkalinity?NaCl,Na₂SO₄,NaHCO₃,Na₂CO₃?were used to treat the seeds and seedlings of Lycium ruthenicum,and the seeds and seedling physiological properties under the stress of single salt?NaCl?and salinity-alkalinity?NaCl,Na₂SO₄,NaHCO₃,Na₂CO₃?were analyzed.The main results are as follows:?1?The wild ecological investigation of 8 communities of dominant species of desert plant Lycium ruthenicum,which were from different water-salt environment,desert soil types and distance in the Ejina area of the lower reaches of Heihe River,showed that the communities was composed of 15 species plants of 7 families and 15 genera.The dominant plants included: Lycium ruthenicum,Karelinia caspica and and Reaumuria soongorica;the Lycium ruthenicum which grows far away from the riverway where is the mild saline desert showed random distribution,while others showed aggregative distribution;The Simpson index of the community diversity range was 0.51-0.94,the range of Margalef index was 1.33-4.1,the range of Pielou index was 0.16-0.80 and the range of Shannon-Wiener index was 0.11-0.88;The CCA sequencing analysis showed that the Simpson and Shannon-Wiener index were mainly influenced by the contents of soil Mg²⁺,K⁺ and SO₄^2-,Pielou index was mainly influenced by the contents of soil SO₄^2-,Ca²⁺,CO₃^2-,K ⁺ and p H,Margalef index was mainly influenced by the contents of soil Cl^-,Mg²⁺ and HCO3-.Lycium ruthenicum communities species composition was relatively rare,species distribution was not uniform,the structure was relatively simple and communities species diversity was low.?2?Study on the leaf functional traits and its response to soil environment of Lycium ruthenicum,SLA showed significantly positive relationship with LDMC and LD?P<0.01?,SLV was significantly negatively correlated with LDMC?P<0.01?,and showed significant and positive correlation to TWC?P<0.01?and RWC?P<0.05?.LDMC was most significantly positively correlated with LD?P<0.01?,C content was negatively correlated with P content?P<0.05?,P showed significantly negative relationship with N/P and C/P?P<0.01?,N was most negatively correlated with C/N?P<0.01?;The surface soil salinity?0-20cm?was positively correlated with LT?P<0.05?,SLV?P<0.05?,Suc?P<0.05?,TWC?P<0.05?and RWC?P<0.01?,was significantly negative correlated with C and N?P<0.01?,and significantly and positively correlated with C/N?P<0.01?.SLA,SLV,LDMC were the key leaf water traits of Lycium ruthenicum to reflect desert stress adaptability;Lycium ruthenicum leaf C/P and N/P values were mainly determined by the change of P content,the C/N value was mainly determined by the change of N content;leaf N/P?8.78?<14,which indicated that the growth of Lycium ruthenicum in the lower reaches of the Heihe River was more susceptible to N element;The relationship of leaf functional traits and surface soil salinity?0-20 cm?reflected salt tolerance and drought resistance adaptive strategies of desert plant.?3?The study of NaCl stress on the growth of the Lycium ruthenicum showed that NaCl concentration was 150 mM,the water content,dry weight and plant height of the Lycium ruthenicum seedlings were highest;Compared with the control treatment,salt treatment could significantly increase Na⁺ concentration in its leaves and stems,the concentration of Na⁺ in the aerial part was higher than that of the root;The roots and stems of the Lycium ruthenicum could maintain the stability of K ⁺ under the stress of NaCl;When the concentration of NaCl were 50,100,150 and 200 mM,the K⁺ / Na⁺ ion in the roots of the Lycium ruthenicum increased by 167%,68%,106% and 98%.The results indicated that proper NaCl concentration?150mM?could improve the growth of the Lycium ruthenicum seedlings;The accumulation of Na⁺ in the aerial part could improve the water status;NaCl concentration was in the range of 50-200 mM,the salt tolerance of the Lycium ruthenicum was enhanced.?4?The study of complex salinity-alkalinity stress showed that A,B,C group seed germination index were higher than the control in salt concentration 5-25 mM,when the salt concentration was over 75 mM,the seed germination was inhibited with the increase of salt concentration;The electrolyte leakage was the largest at high salt concentration?350mM?,when the alkaline enhanced,the electrolyte leakage increased;Under a certain salt concentration range?5mM-125 mM?,the water content of the Lycium ruthenicum leaves and stem were relatively stable,when the salt concentration was over 125 mM,the water content of the leaves and stem reduced with the increase of salt concentration,the water content of the leaves and stem were the least at high salt concentration?350mM?,when the alkaline enhanced,the water content reduced;Under a certain salt concentration range?5mM-125 mM?,Lycium ruthenicum seedings growed well,when the salt concentration was over 200 mM,the survival rate decreased with the increase of salt concentration,the survival rate of C,D,E group were lowest at high salt concentration?350mM?.The results indicated that low salt concentrations?5-25 mM?and appropriate alkaline conditions could promote germination of Lycium ruthenicum seeds;salt concentration had significant effect on seedings water content and survival rate,while the effect of synergistic interaction between salt concentration and p H was also significant.