| >Basically, as others have said, there is an evolutionary reason plants do not naturally grow this big (they'd kill themselves off in a few generations). The undomesticated cultivars which evolved over time evolved to work in their niche. Potatoes largely come from the Andes in Peru/Chile, where the soil is thin, rocky and the terrain is very mountainous. So potatoes evolved to develop in poor quality mountainous soil. What we do as humans in domesticating these cultivars is important because we grow potatoes in very different situations, and we develop new potato cultivar that are adapted to our new environments. So you see, it's not "an evolutionary reason plants don't grow big", it's "they evolved to fill a niche". When we change the niche, we change the pressures on them, and we create an opportunity for us to adapt the new plant even better. I don't think there is as much worry about fertilizer as you think. When growing crops we are long past the time when you rely on natural fertilizer. Nearly every atom in those plants that isn't Carbon was added to the soil explicitly to grow that plant. So, to grow bigger potato, you will need more fertilizer. With regards to climate, being able to grow more rice per acre is valuable because climate change will destroy breadbasket regions and likely reduce total land available to agriculture. Thus maintaining total output levels against decreasing land total will be important. |