International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria.
Institute of Life and Earth Sciences, Pan African University, University of Ibadan, Ibadan, Nigeria.
PLoS One. 2022 Aug 18;17(8):e0269670. doi: 10.1371/journal.pone.0269670. eCollection 2022.
Hand pollination success rate is low in yam (Dioscorea spp.), due partly to suboptimal weather conditions. Thus, determining the most suitable time for pollination could improve the pollination success in yam breeding programs. We performed continuous hand pollination within flowering windows of D. rotundata and D. alata for two consecutive years to determine the most appropriate month, week, and hours of the day allowing maximum pollination success. In D. alata crossing block, we observed significant differences among crossing hours for pollination success (p = 0.003); morning hours (8-12 a.m.) being more conducive than afternoons (12-5 p.m.). No significant differences existed between crossing hours in D. rotundata, though the mid-day seemed optimal. For both species, the time interval 11-12 a.m. was more appropriate for crossing while 4-5 p.m. was the poorest. However, in vitro pollen germination tests showed that mid-day pollen collection (12 noon-2 p.m.) had better results than both extremes, though there were strong genotypic effects on outcomes. Pollination success rates differed significantly among months for D. alata (p < 0.001) but not for D. rotundata (p > 0.05). Differences in pollination success existed across weeks within flowering windows of both D. alata (p < 0.001) and D. rotundata (p = 0.004). The seed production efficiency (SPE) had a similar trend as the pollination success rate. No clear pattern existed between the pollination time and the seed setting rate (SSR) or seed viability (SV), though their dynamics varied with weeks and months. This study provided an insight on the dynamics of pollination outcomes under the influence of pollination times and allows detecting months, weeks, and hours of the day when hybridization activities should be focused for better results.
山药（薯蓣属）的人工授粉成功率较低，部分原因是天气条件不理想。因此，确定最适合授粉的时间可以提高山药育种计划的授粉成功率。我们在两年内连续对薯蓣属的圆叶薯蓣和山薯进行了开花窗口内的连续人工授粉，以确定允许最大授粉成功率的最适合月份、周和一天中的小时。在山薯杂交块中，我们观察到授粉成功率在杂交小时之间存在显著差异（p=0.003）；上午（8-12 点）比下午（12-5 点）更有利于授粉。在圆叶薯蓣中，杂交小时之间没有显著差异，尽管中午似乎是最佳时间。对于这两个物种，11-12 点之间的时间间隔更适合杂交，而 4-5 点之间的时间间隔最差。然而，体外花粉萌发试验表明，中午（12 点-2 点）采集花粉的结果比两个极端都要好，尽管存在强烈的基因型对结果的影响。山薯的授粉成功率在不同月份之间存在显著差异（p<0.001），但在圆叶薯蓣中则没有（p>0.05）。在山薯和圆叶薯蓣的开花窗口内，不同周之间的授粉成功率存在差异（p<0.001 和 p=0.004）。种子生产效率（SPE）与授粉成功率有相似的趋势。授粉时间与结实率（SSR）或种子活力（SV）之间没有明显的关系，尽管它们的动态随周和月而变化。本研究提供了一个关于授粉结果动态的见解，受授粉时间的影响，并可以检测出应该集中杂交活动的月份、周和一天中的小时，以获得更好的结果。
