Apples in the subtropics

I read most of Biology of Apples and Pears, and though much of it went way over my head, I learned a lot about apples and pears in the subtropics. The passage (click on it for a full-sized version) above sums up the techniques: 1) Horizontal training of branches to release lateral buds from apical dominance; 2) Leaf stripping to prevent return to deep dormancy; 3) Depriving the trees of water. All these mechanical treatments cause the trees to enter dormancy, undergoing essentially the same physiological changes that cold weather causes up north.

Dormancy, according to this book, is a very poorly understood phenomenon, a result of multiple causes that include, but are not limited to, cold weather.