Explanation:




Pinus seeds are the seeds of pine trees and they have a unique relationship with a type of fungi called mycorrhiza. Mycorrhiza is a mutualistic association between the roots of plants and the hyphae of certain fungi. This relationship is important for the successful germination and growth of Pinus seeds.



Reasons for Pinus seeds requiring mycorrhiza for germination:



1. Nutrient uptake: Mycorrhiza helps in the absorption of nutrients, especially phosphorus, from the soil. Pinus seeds have limited reserves of nutrients, and they heavily rely on mycorrhiza to acquire essential nutrients from the soil. Without mycorrhiza, the seeds would not be able to access sufficient nutrients for germination and growth.

2. Water absorption: Mycorrhiza also plays a crucial role in improving the water absorption capacity of Pinus seeds. The hyphae of mycorrhizal fungi extend into the soil and form a network that increases the surface area for water absorption. This is particularly important for Pinus seeds as they have a relatively low water content and require adequate water for germination. Without mycorrhiza, the seeds may not be able to absorb enough water for successful germination.

3. Protection against pathogens: Mycorrhiza provides a protective barrier against soil pathogens. The hyphae of mycorrhizal fungi create a physical barrier around the roots of Pinus trees, preventing the entry of harmful pathogens. This protection is especially important during the early stages of seed germination when the seeds are vulnerable to pathogen attack. Without mycorrhiza, the seeds may be more susceptible to infections and may fail to germinate.



Conclusion:



In conclusion, Pinus seeds require mycorrhiza for germination because mycorrhiza helps in nutrient uptake, water absorption, and protection against pathogens. Without mycorrhiza, the seeds would not have access to sufficient nutrients, water, and protection, which are essential for successful germination and growth. Therefore, the correct answer to the given question is option C - mycorrhiza.