Effects of mycorrhizal fungi on the growth and mineral element uptake of Cymbidium goeringii

http://www.dfac.cc/showtopic-7-243740-0-0-1.htm

Mycorrhizal fungi have a clear effect on increasing the weight of Cymbidium goeringii and significantly promote its growth. Under the microscope, the nutritional roots of inoculated seedlings showed hyphae breaking through the root velamen and entering the cortical tissue, forming typical symbiotic structures such as hyphal coils in the cortical tissue: the hyphal coils were unevenly distributed in the cortical cells, and some hyphae located in regions near the cell nucleus were digested, indicating that the inoculated strains could be effectively utilized by Cymbidium goeringii roots. The mycorrhizal fungi invading the root tissue of orchid seedlings can absorb various mineral elements from the external environment and supply them to Cymbidium goeringii, and the mineral element content increased significantly. The content of each mineral element in the seedlings was higher than that in the control uninoculated seedlings, with the increase in trace elements being particularly prominent. Inoculated seedlings produced a large number of new nutritional roots, and the mycorrhizal fungi infected the new roots and formed mycorrhizae through symbiosis, providing Cymbidium goeringii with the necessary nutrients for normal growth and development; the storage roots, however, produced orchid phenols that resisted fungal infection. Therefore, it is considered that mycorrhizal fungi can induce Cymbidium goeringii to produce a large number of new roots, which not only facilitates massive fungal invasion but also allows Cymbidium goeringii to absorb more nutrients provided by the fungi, thereby enabling both parties to achieve a mutually beneficial symbiotic relationship.

Comparison of the growth of orchid seedlings inoculated with mycorrhizal fungi versus uninoculated ones over the same period!

The microstructure of Cymbidium goeringii roots and fungi was observed, and the results showed that the roots of Cymbidium goeringii have a typical orchid mycorrhizal structure. The mycorrhizal fungi break through the root velamen tissue, making it become depressed pores, then enter the cortical cells through passage cells of the outer cortex to colonize, forming hyphal masses in the nearly circular cells of the middle cortex, mainly distributed in the middle part of the root; the mycorrhizal fungi of Cymbidium goeringii have a certain influence on the size and shape of the host cell nucleus. In the cortical tissue at the base and root tip of Cymbidium goeringii roots, there is almost no distribution of mycorrhizal fungi, but there are many depressed pores on the surface of the root velamen, and septate hyphae exist in the root velamen tissue, which means that soil fungi can enter the root velamen tissue at the root base and root tip but cannot enter the cortical tissue. It has been reported that orchid phenol-like substances in the meristem at the root tip of orchid plants resist fungal invasion. The root base connects to the pseudobulb and is the transition zone linking the root and stem; its cortical tissue microstructure and function undergo some changes, so soil fungi cannot colonize there.