Effects Of Maternal Tree Age And Site Conditions On Salt Resistance Germination Of Robinia Pseudoacacia Seeds

Robinia pseudoacacia,which is one of the important pioneer tree species in afforestation and greening of barren mountain wasteland,is tolerant to light salinity,drought and barrenness and possessing root nodules,can be used for fixations of sand and soil,improvement of saline land,and conservations of water and soil.Robinia pseudoacacia is one of the important afforestation tree species in barren mountain area and coastal saline land in Shandong province.However,the attention payed for whose seed quality is not enough,and systematic comparative study has not been carried out.For these reasons,clarifying the seed quality of Robinia pseudoacacia under different site conditions is vital to subsequent seed selection and seedling growing.The age of seed tree is also an important factor that can affect seed quality,which has not been systematically reported on Robinia pseudoacacia.In this paper,the seeds of young and old Robinia pseudoacacia mother trees in barren hilly areas(Feixian)and coastal saline land(Dongying)of the Yellow River Delta were studied.In order to provide theoretical basis for seedling breeding in saline-alkali land afforestation,the changes of 1000-seed weight,hardness,germination,seedling biomass,root characteristics and physiological and biochemical indexes under salt stress were studied,and the effects of site conditions and age of mother trees on the salt resistance of Robinia pseudoacacia seeds were clarified.The results of the test show that:1.The seed weight of Robinia pseudoacacia of saline land is higher than that in barren hilly land.There was no significant difference in 1000-seed weight between young and old mothers,but the seed imbibition rate was low.2.Compared to those of barren mountain,seeds of Robinia pseudoacacia of saline land have higher germination ability(germination rate,germination potential,germination index,vigor index,radicle length),higher seedling biomass(fresh weight of seedlings,fresh weight of aboveground parts,fresh weight of roots),better root development(length of roots,large surface area of roots,large volume of roots,average diameter of roots),and higher protective enzyme activity(superoxide oxide dismutase),chemical dismutase(SOD),peroxidase(POD),lower malondialdehyde(MDA)content and higher seed quality.3.The younger mother tree Robinia pseudoacacia seeds have higher germination rate,germination potential,germination index,higher seedling fresh weight,larger root length,root surface area and root volume,higher SOD and POD activity,lower MDA content and higher seed quality than the elder mother tree.4.With the increase of salt stress concentration,there was no significant differencebetween CK and 0.1% NaCl except radicle length,SOD and MDA,but the germination ability,seedling biomass and root development decreased significantly from 0.3% NaCl.POD and SOD increased first,and reached the maximum at 0.5% NaCl,then decreased.By comparing seed germination,seedling biomass,root morphology and protective enzyme activity,it was found that locust site conditions and mother tree age had significant effects on seed quality.Under salt stress,the seed of Robinia pseudoacacia mother tree in saline land has higher vigor than that in barren mountain area,which may be related to the long-term adaptation of mother tree to saline environment.