Extracting Mycorrhizal Fungi Spores

The cultivation of mycorrhiza fungi, crucial in the plant ecosystem, involves initial lab and greenhouse processes before spores are ready to be applied to tree seedlings.

Various field sites provide soil samples for identifying and extracting mycorrhizal spores.

At the PlantVillage laboratory in Alupe in Busia County, Kenya, six mycorrhiza species undergo examination under a dissecting microscope after an intricate spore extraction process.

The extraction process starts by measuring 50g of collected soil samples, placing them in a beaker, and suspending them in water while stirring and decanting the mixture.

After decanting the water, soil palettes are transferred to test tubes, balanced by weight, and supplemented with water.

The mixture is then centrifuged in a centrifuge at 2,000 rotations per minute for 5 minutes, and then the suspended water is discarded.

Next, 48% sucrose is added to the substrate in the test tubes, balanced by weight, and centrifuged again at 2,000 rotations per minute, for 1 minute.

The palettes are discarded, and the remaining supernatant is washed with water to remove excess sucrose and transferred to a petri dish.

To protect the spores from nematode attacks, 2 to 3 drops of glutaraldehyde are added to the petri dish and also in viols for storage purposes.

The supernatant is then observed under the dissecting microscope to analyse morphological characteristics, quantify spore numbers, and identify species based on color, size, structure, and aggregation.

Finally, the mycorrhizal fungus spores are isolated using a drum pipette and then transferred to the greenhouse for bulking.

At the greenhouse, normal river sand is sterilised using hot water and steaming, put in 1kg bins, and sorghum planted. The spores are then inoculated in specific bins and monitored for growth.

Maintenance involves watering the plant with distilled water, which is withdrawn after 60 days to stress the plant and cause the spores to reproduce rapidly.

The sorghum plants are fed with a nutrient solution prepared in the lab that contains nitrates to promote growth.

The spores will then be harvested and taken to the lab for examination for quality and quantity.

The mycorrhiza fungi produced in the lab through spore extraction are broadcast on soil mixed with biochar. The soil is then used for potting tree seedlings. 

At PlantVillage, the agroforestry team is applying the fungi to Hass avocado tree seedlings to increase their tolerance to diseases and improve yields. The fungus works by forming a symbiotic relationship with the plant, which helps make phosphorus readily available.