Exploring the density tolerance yield potential paradigm

玉米(Zea Mays L.)育种者在商业粮食产量的持续遗传改良方面取得了极其成功的成就。在美国，在65-70年期间，这一进展约为每年2%，即每年117公斤/公顷，加拿大在杂交时代观察到类似的进展(每年80公斤/公顷)。过去65-70年来的遗传改良是改变玉米植株生理属性的结果。但并不是所有的生理方面都改变了。在粮食产量增加近7倍的同时，非生物胁迫的耐受性也得到了同样令人印象深刻的增强：在此期间，植物种群密度胁迫、氮素胁迫、低温胁迫、水分胁迫、杂草竞争和除草剂的耐受性都得到了提高。令人惊讶的是，鉴于选择的“积极”意想不到的后果，产量潜力没有改变。为什么植物种群密度通过集约化育种表现出遗传改良，而产量潜力保持不变？这项建议探讨了植物密度耐受性和产量潜力之间的关系。玉米籽粒产量的未来增长无疑将通过育种方法和理念的持续演变来实现。通过拟议的研究获得的好处是获得新的知识和专门知识，这可能导致加拿大玉米育种行业未来使用的玉米育种选择方法的范式转变。

Maize (Zea mays L.) breeders have been extremely successful in making continuous genetic improvement in commercial grain yield. In the US, over a 65-70 year period this progress amounts to approximately 2% per year or 117 kg/ha per year, with similar gains observed in Canada during the hybrid era (80 kg/ha per year). The genetic improvement over the past 65-70 years is the result of changing physiological attributes of the corn plant. But not all physiological aspects have changed. Accompanying this nearly 7-fold increase in grain yield was an equally impressive enhancement in general abiotic stress tolerance: plant population density stress, nitrogen stress, cold temperature stress, water stress, weed competition, and herbicide tolerances have been enhanced during this period. Surprisingly, in light of the 'positive' unintended consequences of selection, is that yield potential did not change. Why has plant population density shown genetic improvement through intensive breeding efforts, while yield potential has remained unchanged? This proposal explores the relationship between plant population density tolerance and yield potential. Future gains in maize grain yields will no doubt come about through continued evolution of breeding methodologies and philosophies. Benefits derived via the proposed research are acquisition of new knowledge and expertise that may result in a paradigm shift with regards to future maize breeding selection methodologies utilized by the Canadian maize breeding industry.