Complex sentence: In horticulture, dwarfing is considered a desirable characteristic in modern orchards, where genetic dwarfs may be selected and propagated, or more often, scions are grafted on to dwarfing rootstocks.
Split into simpler sentences: In horticulture, dwarfing can be considered a desirable characteristic in modern orchards. This kind of dwarfing can be attained through selective breeding, genetic engineering, or more often, scions are grafted on to dwarfing rootstocks.