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Function of Orchid Mycorrhiza Questions

Question 1

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Answer 1

The seed will germinate if the conditions remain moist and a compatible fungus is active. The location of the seed is almost irrelevant because seed may germinate on a surface (such as a limb with an epiphytic orchid) or when buried in the soil (terrestrial orchid).

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Question 2

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Answer 2

The fungi appear to be present on the branches, albeit at low densities. They appear to survive either in the outer velamen of the root, or as saprophytes in and on the bark of the supporting tree. New branches appear to become colonised by the fungus by chance events, such as a fragment of an orchid landing and establishing itself. Dispersal of mycorrhizal fungi also takes place, but the mechanism is unclear. Some growers spread seed over apparently uncolonized surfaces, and report germination of seed though not always establishment of plants. This suggests the specific fungi are widespread.

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Question 3

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Answer 3

This has been attempted on many occasions. In contrast to epiphytes, the specific associates of terrestrials appear to be extremely uncommon in soil. The reasons are unclear. The consequences are that the size of colonies of orchids is limited by the spread of the tubers or roots, and the growth of hyphae from adult plants.

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Question 4

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Answer 4

The usual response is yes. Fungi commonly absorb minerals from soil, and have the mechanisms to translocate minerals through their mycelium. Further, the root system of orchids is commonly limited, indicating a severely reduced potential to access sufficient minerals from soil. However, orchids are also commonly slow growing, thus they may not require large amounts of minerals for maintenance, and rely on flushes of minerals such as following rain for their requirements.

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Question 5

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Question 6

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Question 7

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