盐胁迫对4个杜梨半同胞家系幼苗的影响及耐盐机理研究OA

[Objective]This study aims to compare the salt tolerance among four half-sib families of Pyrus betutifolia(YC,LYG,QD14 and QD20)by measuring relevant growth and physiological indicators,and to analyze their salt tolerance mechanisms,thereby providing a scientific basis for the selection,cultivation and promotion of P.betutifolia germplasm in coastal regions.[Method]Seeds of P.betutifolia were collected from three coastal regions:Qingdao,Shandong Province,Lianyungang,Jiangsu Province,and Yancheng,Jiangsu Province.All collection sites were located within 30 km of the coastline.Seeds were harvested from healthy,superior mother trees older than 10 years,and only current-year seeds were gathered.Four half-sib families of P.betutifolia,designated asQD14,QD20,LYGand YC,were established from the collected seeds.The experiment was conducted at the Baima Teaching and Research Base of Nanjing Forestry University,located in Baima Town,Lishui District,Nanjing.On January 20,2019,healthy seeds from the four half-sib families of P.betutifolia,which were plump and free from pests and diseases,were selected and subjected to low-temperature stratification in sand to promote germination.Subsequently,the seeds were germinated at room temperature.After germination,the seeds were transplanted into plastic pots containing a growth medium(the volume ratio of organic nutrient soil to perlite is 9∶1;dry mass 150 g).On June 20,2019,uniformly healthy seedlings with consistent plant height and ground diameter were selected and irrigated with saline solutions at concentrations of 0,0.2%,0.4%,0.6%and 0.8%(mass fraction,where the NaCl mass was calculated as a percentage of the saturated water content of the soil).For each family and each NaCl concentration treatment,a total of 40 seedlings were utilized.Measurements of the salt injury index,root activity,leaf number,root growth indicators(total root length,root surface area,total root volume),soluble sugar and proline contents in leaves,as well as Na+,K+and Ca2+contents in leaves,stems and roots were conducted on days 7,14,21,28,35 and 77 after treatment initiation.[Result]With increasing salt concentration,the salt injury index showed a progressive rise,whereas the growth parameters of both above-and below-ground organs,as well as root activity,declined gradually.However,certain growth traits in the YC family,along with some below-ground growth parameters in the QD14 and QD20 families,exhibited a mild stimulatory effect under low salt conditions.As the salt concentration increased,the contents of soluble sugar and proline in the leaves,as well as the Na+content in the leaves,stems and roots,exhibited a gradual upward trend.In all four P.betutifolia families and across most NaCl treatments,the root consistently displayed the highest Na+accumulation.An exception was observed in the LYG family under 0.8%NaCl treatment,where the Na+content in the leaves exceeded that in both the stems and roots.The contents of K+and Ca2+generally exhibited an initial increase followed by a decrease under increasing salt stress.In both leaves and roots,the ratios of K+／Na+and Ca2+／Na+decreased significantly as the salt concentration rose.Growth and physiological parameters varied considerably among the different families of P.betutifolia in response to elevated salt concentrations.Among the four families evaluated,the YC family demonstrated relatively superior performance in both above-ground and below-ground parts,maintaining higher levels across multiple growth and physiological indicators under salt stress conditions.[Conclusion]Among the four families evaluated,the YC family exhibited the strongest salt tolerance to salt stress compared to the others.In contrast,the LYG and QD14 families showed could not tolerate long-term salt exposure,while the QD20 family was could not tolerate high salt concentrations.Under salt stress conditions,P.betutifolia primarily restricted Na+accumulation within the root system,thereby maintaining relatively low Na+levels in above-ground tissues.Concurrently,the contents of K+and Ca2+remained relatively stable,which contributed to the mitigation of salt-induced damage to leaves and other aerial organs.