Selection against inbred seedlings in mixtures of inbred and hybrid true potato seed

Summary The effect of selection against weak plants was studied in artificial mixtures of hybrid (S₀), first self-pollinated generation (S₁), and second self-pollinated generation (S₂), true potato seed. Selection of vigorous seedlings in true seed populations raised in flats from mixtures of S₀ (25%), S₁ (50%), and S₂ (25%) seed increased the frequency of hybrids to 71%. In another study, two mixtures of S₀ and S₁ seed (1∶3 and 1∶1) were densely sown in beds to produce seedling tubers. Elimination of weak plants during population thinning and subsequent interplant competition significantly reduced the frequency of inbred plants. The resulting seedling tuber progenies were planted in the field and mean yields from the two mixtures of S₀ and S₁ seed were 96% and 99% of related completely hybrid progenies. The implications of these results for TPS production are discussed.