Sources of Error

A number of common errors can occur in the understanding of horizontal resistance, and they must be clearly recognised by the amateur breeder, because they can be dangerously misleading. The first concerns the belief, held by many organic farmers, that organic farming produces plants that have an improved resistance to many parasites. However, good nutrition affects the physiology of the plant, but it does not affect the genetics of the plant. And resistance to parasites is controlled...

Grafting

Recurrent mass selection requires very large numbers of seedlings, almost without limit. Grafting potato scions on to tomato rootstocks is a technique for producing very large numbers of true seeds of potato. Selected potato scions can be grafted on to tomato rootstocks to induce flowering. Being unable to form tubers, the potato scion grows upwards as a vine, with a bunch of flowers every few inches. These flowers can be used for controlled cross-pollination. One good graft can produce up to...