|How do you root fruit trees without grafting?|
That varies depending on type of fruit. Figs, grape vines and blueberry bushes are easy to root with standard methods. Most others (peaches, plums, apples, pears) are quite difficult. Also, by rooting the top you lose the benefits of a rootstock. This includes nematode resistance in nemagard rootstock for peaches and plums, and tree size control in a dwarfing rootstock for apples.
The following website included information on rooting many types of plants. Search for fruit trees under their genus name: Prunus (peach), Pyrus (pear), Malus (apple), etc.
For additional information on rooting landscape trees and shrubs the following web sites should be useful to you: