Doubled haploid versus S1 family recurrent selection for testcross performance in a maize population

Theoretically, in a recurrent selection program, the use of doubled haploids (DH) can increase genetic advance per unit of time. To evaluate the efficiency expected from the use of DH for the improvement of grain yield in a maize (Zea mays L.) population, two recurrent selection programs for testcross performance were initiated using testcross progenies from DH lines and S₁ families. In 4 years one selection cycle using DH and two selection cycles using S₁ families were carried out with the same selection intensity for both methods. As expected, testcross genetic variance was twice as high among DH lines as among S₁ families. The predicted genetic gain was 8.2% for the DH selection cycle, and 10.6% for the two S₁ selection cycles, giving a per year advantage of 29% for the S₁ family method over the DH method with a cycle of 4 years. With a 3-year cycle for the DH method, both methods were expected to be equivalent. Using a tester related to the one used for selection, the genetic gains obtained were equivalent for both methods: 6.6% for the DH cycle and 7.0% for the two S₁ cycles. With a 3-year cycle for the DH method, the advantage would have been in favor of DH method. Furthermore, the DH method has the advantage of simultaneously producing lines that are directly usable as parents of a hybrid. Thus, if the genetic advance per unit of time is evaluated at the level of developed varieties even with the same or with a lower genetic advance in population improvement, the DH method appears to be the most efficient.