Hybrid crop breeding programs using a two-part strategy produced the most genetic gain, but a maximum avoidance of inbreeding crossing scheme was required to increase long-term genetic gain. The two-part strategy uses outbred parents to complete multiple generations per year to reduce the generation interval of hybrid crop breeding programs. The maximum avoidance of inbreeding crossing scheme manages genetic variance by maintaining uniform contributions and inbreeding coefficients across all crosses. This study performed stochastic simulations to quantify the potential of a two-part strategy in combination with two crossing schemes to increase the rate of genetic gain in hybrid crop breeding programs. The two crossing schemes were: (i) a circular crossing scheme, and (ii) a maximum avoidance of inbreeding crossing scheme. The results from this study show that the implementation of genomic selection increased the rate of genetic gain, and that the two-part hybrid crop breeding program generated the highest genetic gain. This study also shows that the maximum avoidance of inbreeding crossing scheme increased long-term genetic gain in two-part hybrid crop breeding programs completing multiple selection cycles per year, as a result of maintaining higher levels of genetic variance over time. The flexibility of the two-part strategy offers further opportunities to integrate new technologies to further increase genetic gain in hybrid crop breeding programs, such as the use of outbred training populations. However, the practical implementation of the two-part strategy will require the development of bespoke transition strategies to fundamentally change the data, logistics, and infrastructure that underpin hybrid crop breeding programs.

中文翻译：

---

在杂交作物育种计划中使用基因组选择的两部分策略

采用两部分策略的杂交作物育种计划产生了最大的遗传增益，但是需要最大程度避免近交杂交计划以增加长期遗传增益。该策略分为两部分，每年使用近亲父母完成多个世代，以减少杂交作物育种计划的世代间隔。通过在所有杂交中保持一致的贡献和近交系数，最大程度避免近交杂交方案来管理遗传变异。这项研究进行了随机模拟，以量化两部分策略与两个杂交方案相结合的潜力，以提高杂交作物育种计划的遗传增益。这两个杂交方案是：（i）循环杂交方案，和（ii）最大程度避免近交杂交方案。这项研究的结果表明，基因组选择的实施提高了遗传增益的速率，并且由两部分组成的杂交作物育种计划产生了最高的遗传增益。这项研究还表明，最大程度地避免了近交杂交方案，这使得两部分杂交作物育种计划的长期遗传增益每年完成多个选择周期，这是由于随着时间的推移保持较高水平的遗传变异的结果。分为两部分的战略的灵活性为整合新技术提供了进一步的机会，以进一步提高杂交作物育种计划的遗传增益，例如使用近交训练种群。但是，两部分策略的实际实施将需要制定定制的过渡策略，以从根本上改变数据，物流，