It's not entirely accurate to say that potatoes thrive when their only source of water is rainwater. While potatoes can survive and produce some yield with just rainwater, they actually do much better with additional irrigation.

Here's why:

* Rainwater variability: Rainfall is unpredictable and inconsistent, leading to periods of drought and flooding. This makes it difficult for potatoes to get the consistent moisture they need for optimal growth.

* Nutrient availability: Rainwater, while essential, doesn't provide all the nutrients potatoes need. Irrigation can help deliver fertilizers and other nutrients that enhance potato growth and yield.

* Soil moisture control: Rainwater can lead to inconsistent soil moisture, which can hinder root development and nutrient uptake. Irrigation allows farmers to control soil moisture levels for better potato growth.

* Disease control: Excess moisture from rainfall can encourage the spread of potato diseases. Irrigation allows for more controlled watering, reducing disease risk.

However, there are some advantages to rainwater:

* Cost-effective: Using rainwater for irrigation can save water and money, especially in areas with limited access to other water sources.

* Environmentally friendly: Relying on rainwater reduces reliance on irrigation systems that may require energy and contribute to water depletion.

* Improved soil health: Rainwater is naturally filtered and can help improve soil health over time.

In conclusion:

Potatoes can survive on rainwater alone, but they don't thrive under these conditions. Irrigation, while potentially expensive, can significantly improve potato yields, quality, and disease resistance. However, using rainwater for irrigation can offer significant environmental and financial benefits.

Ultimately, the best strategy for growing potatoes depends on factors like climate, soil type, and the farmer's resources.