微生物共同作用下的铁皮石斛组培苗生长效应研究

植物体和植物根际均是复杂的微生态系统,其内栖息着关系复杂的共生微生物,共同影响植物的生长发育.为探讨混合接种真菌与细菌对兰科植物生长的影响,筛选出真菌与细菌的优势促生组合,本研究选取经分离、筛选获得的4株促生内生真菌(铁皮石斛内生真菌C22、C35,美花石斛内生真菌L12、L28)和3株促生内生细菌(铁皮石斛菌内生细菌TX-7、TX-16、TX-19),以"真菌+细菌"的方式混合接种于铁皮石斛无菌组培苗中,共培养120 d.结果获得了3组优势组合:C22+TX-19、L28+TX-16和L28+TX-19,它们对铁皮石斛组培苗的生长均表现出正效应,其中C22+TX-19和L28+TX-19对促进组培苗生物量的增长具有协同效应,L28+TX-19对提高组培苗的根分枝率具有协同效应,3个组合对增加组培苗的分蘖数和根尖数均表现为累加效应.研究结果表明,内生真菌与内生细菌的共同作用可显著促进铁皮石斛的生长,混合接种有可能更大地发挥微生物的效能.

Interaction Effect of Symbiotic Microorganisms on Seedling Growth of Dendrobium catenatum Lindley(Orchidaceae)

Complex micro-ecosystems exist between plants and rhizosphere,where various symbiotic microorganisms with complicated interactions jointly influence the growth and deve-lopment of the plant.To better understand the interaction effect of fungi and bacteria on orchid growth,we screened four endophytic fungi that beneficially promote growth,among which two strains were isolated from Dendrobium catenatum and two from Dendrobium loddigesii.Three growth-promoting endophytic bacteria were also screened from D.catenatum,and combinations of tested fungi and bacteria were inoculated on the roots of seedlings for 120 days to investigate the growth effect on D.catenatum.Inocula combinations C22+TX-19,L28+TX-16,and L28+TX-19 demonstrated the best growth effect on the host,showing additive effects on the number of tillers and root tips of seedlings.Moreover,C22+TX-19 and L28+TX-19 combinations synergistically increased seedling biomass,and L28+TX-19 inocula synergistically promoted root branching.Results indicated that interactions between endophytic fungi and endophytic bacteria had significant growth promoting effects on the host.It may be possible to develop endophytic inocula for orchid growth.