Effects of forty-two strains of orchid mycorrhizal fungi on growth of plantlets of Anoectochilus roxburghii

Anoectochilus roxburghii, a rare medicinal herb in China, is difficult in artificial propagation and symbiotic with endophytic fungi for its development and accumulation of bioactive compounds in it. In order to establish a symbiotic system, we investigated several decades of mycorrhizal fungi from Orchidaceae plants in growth promotion of A. roxburghii. Forty-two strains were inoculated upon plantlets of A. roxburghii and incubated for 40 days. Symbiotic strains were screened out by survival of hosts, and the survival hosts were measured in height and weight in 40 days. Eight of the 42 strains were best for development of the host plantlets, including Strains DC-8 (Epulorhiza sp.), DC-13 (Mycena dendrobii), DN-10 (Moniliopsis sp.), AR-10 (Gliocladium sp.), AR-11 (Gliocladium sp.), AR-13 (Mycena anoectochila), AR-15 (Epulorhiza sp.) and AR-18 (Epulorhiza sp.). Compared with the control, inoculated plantlets had 25.61-59.76% increment in height and 33.33-61.67% in weight, respectively. Statistical analysis showed that significant difference in height occurred in various strains, however, there was no difference in weight. AR-10, AR-11, AR-15, and DC-08 showed significant increment in height, and AR-15 was the best strain (P<0.05) for weight increment. Hyphae colils was observed in co-cultivation of the plantlets and AR-15. DC-13, DC-08, AR-13 and AR-15 were the best strains for the development of Dendrobium candidum and D. nobile and A. roxburghii plantlets, which indicated that those strains might have a broad spectrum of Orchidaceae host and be promising candidates in the establishment of symbiosis system. Several symbiotic cultivation systems have been established, which are the basis for propagation of Anoectochilus roxburghii in agriculture.