[On the problem of change in the proportions of amylose/amylopectin in potato starch through breeding].

85 wild and cultivated potato species of 6120 genotypes from 2818 different sources were investigated in order to find out whether breeding of potato varieties with changed proportions of amylose: amylopectin were possible. The main purpose was to raise the amylose portion of the starch.While the best varieties have proportions of about 28% amylose to 72% amylopectin, clones with 30-33% amylose could be found among cultivated potatoes.A positive correlation between amylose content of the parents and their progeny after selfing, crosses between sibs, and of the mentioned amylose-rich clones with 2 x or 4 xS. tuberosum could be ascertained.A weak negative correlation between the amount of starch content and amylose conten was found which, however, need not be a deterrent to successful breeding.Preliminary results from hybrid progeny indicate the possibility of breeding varieties with increased amylose content. The necessary breeding steps are given.