内生菌对柳树生长及氮磷吸收的强化作用

Bioaugmentation effects of endophytic bacteria on growth and nitrogen and phosphorus accumulation of willow

采用水培试验,比较了8株来源于超积累植物的内生菌(SaMR12、SaZR4、SaMR10、SaNR1、SaCS20、SM03、SM05和LM02)对柳树生长及氮磷吸收的影响。结果表明:接种SaMR12和SaMR10后柳树叶绿素含量显著增加,分别比对照提高了15%和14%;接种LM02、SaNR1和SaMR12对柳树根系生长有明显的促进作用,其中柳树的总根长比对照分别增加了163%、136%和66%,根表面积分别增加了54%、12%和17%,根尖数分别增加了54%、44%和48%;接种LM02、SaMR12和SaMR10后柳树总生物量分别比对照增加了234%、43%和54%;LM02、SaMR12和SaMR10这3株内生菌能显著促进柳树氮磷吸收,其中柳树地上部氮积累量比对照分别增加了176%、26%和41%,根系氮积累量分别是对照的8.3倍、2.4倍和3.4倍,柳树地上部磷积累量比对照分别增加了109%、12%和30%,根系磷积累量分别是对照的4.8倍、2.1倍和2.8倍。研究结果显示,接种LM02、SaMR10和SaMR12对柳树生长和氮磷积累有显著的促进作用,同时,显著提高了对富营养化水体的修复效率。

Due to large biomass,submergence tolerance,rapid growth,well-developed root system and strong adaptability,willow（Salix matsudana）trees were not only widely used in ecological restoration of the heavy metal pollution,organic pollution and eutrophication,but also used as source of biomass energy.To expand the range of application and improve the economic value,it is necessary to enhance the biomass and nutrient accumulation of willow.Phyto-microbial remediation technology was widely used in recent years for it wasenvironmentally friendly,low cost and high efficiency in restoration.With assistance of microbe,the efficiency of phytoremediation was significantly enhanced.Endophytic bacterium,a kind of microbe colonized in plant tissue without causing pathogenicity,could produce plant hormones like gibberellin and indole acetic acid（IAA）to promote plant growth.In this study,willow trees were inoculated by eight endophytic bacteria（SaMR12,SaZR4,SaMR10,SaNR1,SaCS20,SM03,SM05 and LM02）derived from hyperaccumulator Sedum alfredii,and the plant growth and accumulation of nitrogen and phosphorus were investigated.In hydroponics experiment,the willow cuttings were grown in 2.5 L Hoagland＇s solution with physiology upward until root length was above 1cm.And propagation of endophytic bacteria suspension was added to the vessel with final density of 1×108 CFU/mL.The bacterial solution was replaced after 3days.The treatment without bacterial inoculation was used as a control.The willows were observed and determined after 2months of culture.The chlorophyll contents,root morphology,shoot and root biomass,nitrogen and phosphorus accumulation showed significantly different among different endophytic bacteria treatments. Chlorophyll content was significantly increased by 15% and 14% with inoculation of SaMR12 and SaMR10endophytic strains as compared with the control.After inoculation with LM02,SaNR1 and SaMR12,the root morphology was significantly improved.The total root length was increased by 163%,136% and 66%,respectively.Root surface area was increased by 54%,12% and 17%,and the number of root tips was increased by 54%,44% and 48%,respectively.With the inoculation of LM02,SaMR12 and SaMR10,the total biomass of willow was increased by234%,43%and 54%,respectively.The accumulation of nitrogen and phosphorus nutrients was also significantly promoted.Shoot nitrogen accumulation was increased by 176%,26% and 41%,and shoot phosphorus accumulation was increased by 109%,12% and 30%,respectively,as compared with the control.The root nitrogen accumulation was increased by 8.3times,2.4times and 3.4times,and the root phosphorus accumulation was increased by 4.8times,2.1times and 2.8times,respectively,with the inoculation of LM02,SaMR12 and SaMR10.Meanwhile,the concentrations of nitrogen and phosphorus in eutrophic water were significantly decreased.It is concluded that LM02,SaMR10 and SaMR12are more efficient in promotion of plant growth than other endophytic bacteria.These strains also show the enhancement of willow growth for bio-energy and improvement of phytoremediation efficiency,which have a broad application prospect.