ARS | Publication request: ESTIMATES OF HETEROSIS AMONG POPULATIONS OF BULB ONION OF NARROW AND DIVERGENT GENETIC BACKGROUNDS AS DETERMINED BY RANDOM NUCLEAR RFLPS

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 15, 1995
Publication Date: N/A

Technical Abstract: The bulb onion (Allium cepa L.) resembles maize (Zea mays L.) with predominate outcrossing, historical maintenance by open pollination, severe inbreeding depression, and significant heterosis after crossing among inbred lines. Unlike maize, relatively few RFLPs occur among phenotypically diverse onion populations. Phylogenetic estimates based on random nuclear RFLPs revealed a restricted genetic background for some market classes of onion. The question arose whether crossing among onion populations would reveal groups that show significantly greater heterosis. We generated a factorial mating design using a sample of related and divergent (based on random nuclear RFLPs) open-pollinated (OP) populations and estimated combining abilities and heterosis for bulb yield and quality. Our analyses did not reveal any related population from which inbreds would likely combine significantly better with the male- sterile tester lines. Divergent OP populations tended to produce testcrosses with larger bulbs and correlated traits of reduced pungency, soluble solids, and storage ability. Overall, significant GCA estimates indicated that superior onion inbreds and populations may be developed using recurrent-selection strategies that increase the frequency of desirable alleles with additive effects.