Triple test cross predictions of the performance of recombinant inbred lines from a wide cross in onions (Allium cepa)

Abstract

SUMMARYIn conjunction with an onion breeding scheme to produce recombinant inbred lines from a wide cross genetical experiments were carried out to predict the likely outcome. Results are given of genetical predictions, obtained from two triple test cross experiments, of the expected performance of inbred lines derivable by single seed descent from a Japanese × Polish cross. For bulb maturity, c. 12% of the inbred lines are expected to be earlier than the earlier parent; for bulb hardness over 50% of the inbred lines are expected to exceed the better parent. For bulb weight, predictions from the basic model suggest 5–25% of the inbred lines may exceed the better parent, but when this model is modified to take account of the likely inbreeding depression in the open‐pollinated Japanese parent, only 0–2% of such high yielding inbred lines are expected. Other potential sources of bias which may affect the predictions are discussed.