5.4: Mycorrhizae

Question 1

What are mycorrhizae

Answer 1

fungi that live on the surface of the plant roots and have mutualistic symbiosis with the plant

Question 2

Describe the mutualistic symbiosis between a plant and mycorrhizae fungi

Answer 2

The fungi on the plant roots have a branching network of hyphae which grow outwards to areas that the roots can’t reach, this increases the surface area of the roots, increasing uptake of water and minerals
The fungi takes in C compounds from the plant

Question 3

What are 2 limitations of root growth

Answer 3

drought
hard soil textures as the meristem of roots is very soft

Question 4

What are the 4 roles of mycorrhizae

Answer 4

1- expand the nutrient absorption surface of plants
2- increase the absorption of phosphorus by plants
3- enhance plant disease resistance
4- aggregate soil and stimulate microbial activity

Question 5

Why is it important for the plant that mycorrhizae increases the absorption of phosphorus

Answer 5

phosphate ions are the least available mineral ions in the soil, when it is available, a phosphorus poor zone is created around the plant as phosphorus is absorbed almost immediately by the plant. Mycorrhizae are able to reach outside that poor zone and increase surface area for absorption of phosphorus

Question 6

Why is it important for mycorrhizae to aggregate the soil and stimulate microbial activity

Answer 6

they release plant auxins which stimulate microbial activity - nitrifying bacteria and saprobionts - increasing the soil quality.
Also, they pack soil together -> less soil erosion