Abstract Breeding to raise yield potential through enhancing photosynthesis will have limited impact unless harvest index (HI: proportion of above-ground biomass as grain yield) is maintained or ideally increased. Boosting grain dry matter (DM) partitioning will require increased allocation of assimilates to sink organs to enhance spike growth. A high biomass spring wheat panel of 150 genotypes encompassing elite, landrace-derived and synthetic-derived lines was grown under yield potential conditions in two seasons in NW Mexico. Results showed that the incorporation of landrace-derived and synthetic-derived backgrounds into elite lines resulted in higher expression of above-ground biomass (AGDM), leaf lamina and stem DM partitioning at anthesis. However, no grain yield advantage was observed over elite lines, due to lower grain number per unit area (GN) and decreased harvest index (HI). Positive linear associations were found among spike fertility-related traits - fruiting efficiency (grains per unit of spike DM at anthesis; FE), GN and HI - which were, in turn, related positively with grain yield (GY). Stem-internode 3 length and internode 3 DM partioning were negatively associated with spike partitioning index (SPI: ratio of spike DM to total above-ground DM at anthesis) and GN, suggesting an enhanced competition for assimilates between the spike and stem internode 3 during stem elongation. Within-spike DM partitioning analysis (glume, lemma, palea, rachis, awn) showed decreased partitioning to awns was associated with increased FE and thousand grain weight (TGW). While the use of exotic material can enhance biomass, special attention needs to be paid in the selection for novel DM partitioning traits that raise HI and GN coming from the elite genepool. The selection for grain partitioning traits in wheat breeding combined with sources expressing high biomass can potentially allow breeders to increase grain carbon assimilation that will deliver higher yields.

中文翻译：

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探索谷物分配性状的遗传多样性以提高高生物量春小麦面板的产量

摘要 除非收获指数（HI：地上生物量与谷物产量的比例）保持或理想地增加，否则通过增强光合作用来提高产量潜力的育种影响有限。促进谷物干物质 (DM) 分配将需要增加同化物分配到汇器官以促进穗生长。在墨西哥西北部的两个季节在产量潜力条件下种植了一个包含 150 个基因型的高生物量春小麦面板，包括优良品系、地方品种来源和合成来源品系。结果表明，将地方品种和合成来源的背景并入优良品系导致地上生物量 (AGDM)、叶片和茎干 DM 分配在开花期的更高表达。然而，与优良品系相比，没有观察到谷物产量优势，由于较低的单位面积籽粒数 (GN) 和降低的收获指数 (HI)。在穗肥力相关性状 - 结实效率（开花时每单位穗 DM 的谷物数；FE）、GN 和 HI - 之间发现了正线性关联，而这些性状又与谷物产量 (GY) 呈正相关。茎节间 3 长度和节间 3 DM 分割与穗分割指数（SPI：开花时穗 DM 与总地上 DM 的比率）和 GN 呈负相关，表明在穗和茎节间 3 之间同化物的竞争增强茎伸长。穗内 DM 分配分析（颖片、外稃、外稃、轴、芒）显示芒分配减少与 FE 和千粒重 (TGW) 的增加有关。虽然使用外来材料可以提高生物量，在选择新的 DM 分区性状时需要特别注意，这些性状提高了来自精英基因库的 HI 和 GN。小麦育种中谷物分配性状的选择与表达高生物量的来源相结合，可能使育种者增加谷物碳同化，从而获得更高的产量。