Department of Crop and Forest Sciences and AGROTECNIO (Center for Research in Agrotechnology), University of Lleida, Av. Rovira Roure 191, 25198 Lleida, Spain.
J Exp Bot. 2013 Jul;64(10):2859-69. doi: 10.1093/jxb/ert129. Epub 2013 May 13.
Survival of floret primordia initiated seems critical for the determination of grain number and yield in wheat, and understanding what determines floret mortality would help in the development of more robust physiological models of yield determination. The growth of the juvenile spikes has been frequently considered the determinant of grain number, implying that floret development would depend on resource availability and that the onset of floret death would be related to spike growth. However, this model has been recently challenged from a study concluding that floret death started when the most advanced floret primordia reached a particular developmental stage. As the few previous studies on this relationship involved photoperiod treatments which affect both floret development and the onset of spike growth, conclusions cannot be considered mechanistic. This comprehensive study analysed in detail floret development in wheat as affected by resource availability (mainly soil nitrogen levels) and found that the onset of floret death may occur when development of the most advanced florets ranged from stages 5 to 9 and that the average and standard deviation of floret developmental stage coinciding with the onset of floret death was not related to the level of availability of resources. These results provide further support to the model relating the onset of floret death with the initiation of active growth of the juvenile spike in which florets are developing.
小花原基的存活对于小麦的籽粒数量和产量的决定似乎至关重要，了解决定小花死亡率的因素将有助于开发更稳健的产量决定生理模型。幼穗的生长经常被认为是籽粒数量的决定因素，这意味着小花的发育将取决于资源的可用性，而小花的死亡将与幼穗的生长有关。然而，最近的一项研究对这一模型提出了挑战，该研究得出的结论是，当最先进的小花原基达到特定的发育阶段时，小花的死亡就开始了。由于之前关于这种关系的少数研究涉及光周期处理，这会影响小花的发育和幼穗生长的开始，因此不能认为这些结论具有机械性。这项综合研究详细分析了资源可用性（主要是土壤氮水平）对小麦小花发育的影响，发现小花死亡的开始可能发生在最先进的小花发育阶段为 5 到 9 时，并且与小花死亡开始时小花发育阶段的平均值和标准差与资源可用性水平无关。这些结果为与幼穗活跃生长开始时小花死亡开始的模型提供了进一步的支持，在该模型中，小花正在发育。
