Well-done!
Good photo with clear labels and useful description.

Sexual reproduction of Rhizopus sp. take place when they encounter adverse conditions (e.g. dryness, food shortage).
Other then being the only diploid stage in life cycle of Rhizopus sp., the zygospores also surrounded by a thick wall (forming zygosporangium) to allow them to undergo dormancy during adverse conditions.

For example, fruit skins are tough and resistant, fungi might not be easily access the nutrient inside the fruit (adverse condition: food shortage). However, zygospores could stay dormant on the skin until the fruit ages and the skin loses its toughness (favourable condition). Sporangium will then germinate from the zygospore for dispersal of haploid spores on the fruit surface, the offspring could now easily access the nutrients inside the fruit and grow successfully.

Q) How long can the stage of dormancy last at most?

Yin Nam: Thanks for your extra information and explanation.