Genetic analyses of seed yield in onion

Development of two-way onion (Allium cepa L.) hybrids is difficult due to p oor seed yields on inbred female parents. Seed yield of onion is affected b y inbreeding depression and the seed-production environment. A standard dia llel was used to estimate combining abilities for seed yield among seven in bred onion lines. Males and hybrids differed significantly (P < 0.05) for s eed yields. Combinations of relatively high-by-high seed-yielding inbred pa rents were not always the best combinations; combinations of medium-by-medi um or medium-by-high seed yielders also produced good F-1 seed yielders. Fo r the seven inbred lines, significant correlations (P < 0.05) were observed between mean seed yield per bulb and scape height. Parent-offspring regres sions revealed no significant relationship between seed yields of randomly selected, open-pollinated bulbs and their S-1 families. Results indicate th at relative seed yields of individual bulbs after self-pollination cannot b e used to predict seed yields of progeny families. However, the seed yield of inbred lines of onion may reflect the potential seed yield of F-1 male-s terile lines.