红树林固氮菌和解磷菌的分离及对秋茄苗的促生效果

采用选择性培养基富集培养,结合形态及生长性状等特征分析,分别从广东湛江、珠海及海南东寨港等样地的木榄Bruguiera gymnorrhiza、海莲B.sexangula、秋茄Kandelia candel、红海榄Rhizophora stylosa、无瓣海桑Sonneratiaapetala和海桑S.caseolaris这6种红树植物根际中分离出固氮菌和解鳞菌共59株.秋茄盆栽接种试验结果表明,上述样地分离出的部分解磷菌和固氮菌对秋茄苗的高生长和生物量增长有明显促进作用,其中1株解磷菌He4#单菌株接种的秋茄苗高、根干质量和总生物量比对照分别增长58.4%、132.1%和133.2%,该菌株比国外引进的1株解磷菌地衣芽孢杆菌Bacillus lichenciformis的促生效果更好,前者接种的秋茄根生物量和总生物量比后者高72.7%和90.2%.7株固氮菌的单接种对秋茄苗表现出不同程度的促进作用,其中菌株Ngqq-R14的促生效果最佳,苗高、地径、茎干质量、根干质量和总生物量分别比对照增长38.36%、16.19%、75.46%、49.97%和59.31%.将7株固氮菌和7株解磷菌交互配对成7个菌株组合并接种到秋茄苗的根部,接种6个月后各菌株组合处理组的苗高、茎干质量、根干质量和总生物量分别比对照增长21.1%～69.4%,70.7%～271.5%,27.1%～111.3%和66.9%～123.8%,表明固氮菌与解磷菌之间存在一定的协同增效作用,促进秋茄生长的最佳接菌组合是Nlqq-Wy4+P12.

Isolation of Nitrogen-Fixing Bacteria and Phosphate-Solubilizing Bacteria from the Rhizosphere of Mangrove Plants and Their Enhancement to the Growth of Kandelia candel Seedlings

Fifty nine isolates of nitrogen-fixing bacteria and phosphate-solubilizing bacteria were isolated based on the characteristics of morphology and growth of the bacteria on the selective growth media from the rhizosphere of mangrove plants including Bruguiera gymnorhiza,B.sexangula,Kandelia candel,Rhizophora stylosa,Sonneratia apetala and S.caseolaris in Zhanjiang and Zhuhai,Guangdong Province and Dongzhai harbor,Hainan Island.Among them 7 isolates of nitrogen-fixing bacteria and 8 isolates of phosphate-solubilizing bacteria were screened as propagule inoculants of K.candel in a series of potted experiments to examine their capability to promote the growth of plants.The results showed that the inoculation with a single isolate of phosphate-solubilizing bacteria He4# resulted in a significant increase in plant height,root mass and total biomass at the rate of 58.4%,132.1% and 133.2%,respectively.The enhancement of isolate He4# on the plant growth is more significant than that of an alien isolate(Bacillus lichenciformis).The root biomass and total biomass of K.candel inoculated He4# increased by 72.7% and 90.2% than those inoculated B.lichenciformis.All pure inoculations with 7 different isolates of nitrogen-fixing bacteria showed positive response to the plant growth,and the inoculation with isolate Ngqq-R14 resulted in the maximum increase in plant height,stem diameter,stem dry mass,root dry mass and total biomass at the rate of 38.36%,16.19%,75.46%,51.55% and 59.31%,respectively.Dual inoculations with 7 mixtures of one isolate of nitrogen-fixing bacteria and one isolate of phosphate-solubilizing bacteria could result in synergistic effect on the growth of the seedlings of K.candel,and the increase of plant height,stem dry mass,root dry mass and total biomass were 21.1%-69.4%,70.7%-271.3%,27.1%-111.3% and 66.9%-123.8% respectively.It can be concluded that using mixed cultures of microorganisms is advantageous over pure cultures,and the inoculation of mangroves with phosphate-solubilizing bacteria and nitrogen-fixing bacteria will promote the growth of mangrove plants.