Data from: Long term on-farm participatory maize breeding by stratified mass selection retains molecular diversity while improving agronomic performance

Modern maize breeding programs gave rise to genetically uniform varieties that can affect maize's capacity to cope with increasing climate unpredictability. Maize populations, genetically more heterogeneous, can evolve and better adapt to a broader range of edaphic-climatic conditions. These populations usually suffer from low yields; it is therefore desirable to improve their agronomic performance while maintaining their valuable diversity levels. With this objective, a long-term participatory breeding/on-farm conservation program was established in Portugal. In this program maize populations were subject to stratified mass selection. The current work aims to estimate the effect of on-farm stratified mass selection on the agronomic performance, quality, and molecular diversity of two historical maize populations. Multi-location field trials, comparing the initial populations with the derived selection cycles, showed that this selection methodology led to agronomic improvement for one of the populations. The molecular diversity analysis, using microsatellites, revealed that overall genetic diversity in both populations was maintained throughout selection. The comparison of quality parameters between the initial populations and the derived selection cycles was done using kernel from a common garden experiment. This analysis showed that the majority of the quality traits evaluated progressed erratically over time. In conclusion, this breeding approach, through simple and low-cost methodologies, proved to be an alternative strategy for genetic resources’ on-farm conservation.

现代玉米育种项目培育出遗传均一性较高的品种，这类品种可能会降低玉米应对日趋复杂的气候不确定性的适应能力。遗传异质性更强的玉米群体则可通过自然演化，更好地适配更广泛的土壤-气候复合生境。但这类群体通常存在产量偏低的问题，因此亟需在保留其珍贵遗传多样性的前提下，提升其农艺性状表现。基于这一目标，葡萄牙启动了一项长期参与式育种与农场原位保护项目，该项目中研究人员对玉米群体实施了分层混合选择方案。本研究旨在评估农场原位分层混合选择对两个历史玉米群体的农艺性状、品质及分子多样性的影响。通过多点田间试验对比初始群体与各选育世代群体的表现，结果显示该选择方法可提升其中一个群体的农艺性状表现。采用微卫星标记（microsatellite）开展的分子多样性分析表明，选育过程中两个群体的整体遗传多样性均得以保留。研究人员借助共同种植试验获得的籽粒样本，对比了初始群体与各选育世代群体的品质参数差异，分析结果显示绝大多数被测品质性状随选育进程呈现出无规律的波动变化。综上，该育种方案凭借简便易行且成本低廉的技术手段，被证实为一种可用于作物遗传资源农场原位保护的可行策略。