Which two countries were affected the most economically and demographic by the potato in the Columbian Exchange?

According to  href="http://daphne.palomar.edu/scrout/colexc.htm">Steven J. Crouthamel,
Professor and  Chair of American Indian and American Studies of Palomar College, the
Columbian Exchange is a concept that arose out of collaborative academic negotiation in
preparation for the "Quincentennial of Columbus' voyage to the Americas." The issue of
how to celebrate arose because of the concerns and protests resounding from within
Native American communities. The Columbian Exchange was developed as a way to look at
both the good and harmful effects on the Americas and the world of Columbus' voyage. One
of the top five academically agreed upon biological and cultural impacts was the potato
exchange.

According to the href="http://www.ihs.issaquah.wednet.edu/Teachers/petersen/European%20Studies/Textbook/Chapter%2020/Columbian%20Exchange%2020%204.pdf">The
Atlantic World resource for understanding the Columbian Exchange,
aside from corn, the most significant food exchanged from the Americas to Europe and
Asia was the href="http://daphne.palomar.edu/scrout/potato.htm">potato (The
Atlantic World includes the sweet potato introduced in Asia). The potato,
grown at high freezing altitudes by the Quechua people of the Andes, was well adapted
for cultivation in the northern climes and overworked soils of Europe. Most notably,
life in Ireland was altered by the potato cultivation. Similarly, life was as
dramatically changed in China by the introduction of the sweet potato. Academicians
regret that more varieties of the potato were not exchanged because, as Crouthamel says,
there were Peruvian varieties that were disease
resistant.

The introduction of the potato--and sweet
potato--had affects of great magnitude on economic and demographic concerns. Firstly, a
new agricultural industry was introduced, which led to greater economic opportunity
along with accumulation of wealth for people in the lower classes. Secondly, as pointed
out by Crouthamel, people in countries like Ireland, Poland, Holland, Germany, as well
as China (The Atlantic Monthly) had a new food source high in
vitamins and minerals. This seemingly trivial addition to the food supply kept many from
outright starvation, as Crouthamel points out, and strengthened the lower classes
physically, which led in Europe to the development of a viable labor force for the start
of the later industrial revolution.