how to breed the perfect apple

摘要

Planting apples is a game of chance in which every seed is a wild card. The pome's genetics are so diverse that kernels from the same core sprout into entirely different varieties. Though all cultivars are the same species, we've bred them into more than 7,000 types. Growers must select the best and graft their branches onto new trees to propagate each distinct fruit. Farmers have been doing this since we first domesticated the apple some 2,000 years ago. Here's how we developed some of the varieties.