Mycorrhizae and Their Role in Agriculture

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Questions and Answers

What is the primary role of Rhizoctonia spp. in orchid mycorrhizae?

They help orchids absorb water more efficiently.

They provide structural support to orchid roots.

They protect orchids from fungal diseases.

They break down organic matter, providing essential nutrients to orchids. (correct)

What is a key structural feature of arbutoid mycorrhizae that differentiates them from ectomycorrhizae?

The formation of Hartig net within the host's root cortex.

The formation of arbuscules within the root cells.

The absence of a hyphal sheath around the root tips.

The presence of intracellular hyphae that penetrate root cells. (correct)

Which of the following is NOT an example of a host plant for arbutoid mycorrhizae?

Rhododendron ponticum (Rhododendron).

Arbutus menziesii (Pacific madrone)

Pinus sylvestris (Scots pine) (correct)

Arctostaphylos uva-ursi (Bearberry)

Which type of mycorrhizae plays a crucial role in the establishment and growth of forest trees?

Ectomycorrhizae (B) Signup and view all the answers

How do mycorrhizal inoculants contribute to sustainable agriculture?

They enhance crop yields and reduce the reliance on chemical fertilizers. (B) Signup and view all the answers

Which application of mycorrhizal fungi involves improving the growth and health of ornamental plants in nurseries?

Horticulture (B) Signup and view all the answers

Mycorrhizal fungi are used in reforestation projects to benefit which aspect of tree seedling growth?

Improved survival and growth in degraded lands. (C) Signup and view all the answers

Which type of plants are unlikely to form mycorrhizal associations?

Fungi (B) Signup and view all the answers

Which of the following is NOT a characteristic of arbutoid mycorrhizae?

They lack intracellular hyphae, instead relying solely on external hyphae for nutrient exchange. (B) Signup and view all the answers

What is the primary function of pelotons in orchid mycorrhizae?

To increase the surface area for nutrient absorption within the orchid root. (A) Signup and view all the answers

In the context of sustainable agriculture, how do arbuscular mycorrhizal fungi contribute to nutrient management?

They enhance the plant's ability to uptake nutrients from the soil, reducing the need for chemical fertilizers. (C) Signup and view all the answers

Which of the following mycorrhizal associations is NOT primarily focused on enhancing nutrient uptake for the host plant?

Ectomycorrhizae. (D) Signup and view all the answers

To improve the establishment and growth of forest trees in reforestation projects, which type of mycorrhizae is most commonly used?

Ectomycorrhizae. (B) Signup and view all the answers

What is the primary difference between arbutoid mycorrhizae and ectomycorrhizae?

Arbutoid mycorrhizae are associated with specific plant families such as Ericaceae, unlike ectomycorrhizae. (B) Signup and view all the answers

Which of the following is a common example of an orchid mycorrhizal fungus?

Ceratobasidium cornigerum. (C) Signup and view all the answers

How do mycorrhizal inoculants benefit nursery-grown ornamental plants like roses?

They enhance the plants' resistance to soil-borne diseases. (A) Signup and view all the answers

Study Notes

Orchid Mycorrhizae

Orchid mycorrhizal fungi form associations with orchid roots.
These fungi are essential for orchid seed germination and early development, as orchid seeds lack sufficient nutrient reserves.
Coiled hyphal structures (pelotons) form within orchid root cells.
Orchids are from the Orchidaceae family.
Common fungi include Rhizoctonia spp., providing essential nutrients for growth.
Another fungus associated with orchids is Ceratobasidium cornigerum.

Arbutoid Mycorrhizae

These mycorrhizae resemble ectomycorrhizae but are specifically associated with plant families like Ericaceae.
They form a dense hyphal sheath around roots, penetrating root cells.
The hyphal sheath surrounds the root tips.
Intracellular hyphae form coils or pelotons within root cells.
Host plants include Arbutus and Arctostaphylos, such as Arbutus menziesii (Pacific madrone) and Arctostaphylos uva-ursi (Bearberry).
These associations enhance nutrient uptake and soil stabilization.

Applications in Agriculture

Sustainable Agriculture: Mycorrhizae reduce reliance on chemical fertilizers and pesticides.
- Example: Inoculating maize with arbuscular mycorrhizal fungi reduces phosphorus fertilizer needs, supporting sustainable crop production and reducing environmental impact.
Horticulture: Mycorrhizal inoculants improve ornamental plant growth and health, including disease resistance.
- Example: Application to nursery-grown roses (Rosa spp.) enhances their establishment, growth, and resistance to soil-borne diseases.
Forestry: Mycorrhizae are critical for establishing and growing forest trees, used in reforestation and afforestation:
- Example: Ectomycorrhizal fungi improve the survival and growth of tree seedlings in degraded lands, aiding forest regeneration and ecosystem recovery.
Crop Production: Mycorrhizae enhance growth and yield of crops like maize, wheat, rice, and legumes.
- Example: Inoculating wheat with arbuscular mycorrhizal fungi improves nutrient uptake and grain yield, enhancing overall crop productivity and food security.

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Description

This quiz explores the fascinating world of mycorrhizae, focusing on orchid and arbutoid mycorrhizal fungi and their critical roles in plant nutrition and development. Understand how these fungi support seed germination and contribute to sustainable agriculture practices by reducing chemical inputs.