Hybrid potato crops can be grown from true potato seeds or from seedling tubers. True-seed-grown plants produce lower marketable tuber yield than seedling-tuber-grown plants, because of their low early vigour and distinct growth and development patterns, notably in term of main stem number and stem branching. These differences are pivotal for yield formation but their impacts on crop performance and yield are not well understood. We quantified the differences between the propagule types (true seeds vs seedling tubers) in their branching responses to stem density and assessed to what extent these differences contribute to differences in crop development and tuber production. Two field experiments were conducted in different years, planting transplants from true seeds and pre-sprouted seedling tubers from the same genotype, while controlling their stem density per unit area. Responses in stem branching and biomass partitioning to stem density were quantified on individual main stems, followed by an evaluation of the impact of these responses on crop performance. On individual main stems in both propagule types, higher stem density decreased branch development, decreased the number of branches above- and belowground, resulted in shifts in aboveground branch distribution towards lower branching orders, and led to smaller tuber sizes. However, such branching responses were stronger in true-seed-grown plants than in seedling-tuber-grown plants. At crop level, differences between propagule types were significant in canopy duration, number of tubers, tuber size distribution and marketable yield, but there was no stem density effect. Our results emphasized the differences between propagule types in branching and its impact on crop development and tuber yield, due to the absence of stem density effects. Propagule type effects could be attributed to intrinsic differences between propagule types in branching control, growth habit and source-sink relations. These effects are relevant for hybrid potato breeding and require further research. Management practices were partly responsible for year-to-year differences in branching and yield formation, which highlights their significance for hybrid potato production.

中文翻译：

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分枝对茎密度的响应及其对真种和幼苗块茎杂交马铃薯产量的影响


杂交马铃薯作物可以用真正的马铃薯种子或幼苗块茎种植。真正的种子生长的植物比幼苗块茎生长的植物产生较低的可销售块茎产量，因为它们的早期活力低且生长和发育模式不同，特别是在主茎数量和茎分枝方面。这些差异对于产量形成至关重要，但它们对作物性能和产量的影响尚不清楚。我们量化了繁殖体类型（真种子与幼苗块茎）对茎密度的分枝反应的差异，并评估了这些差异在多大程度上导致了作物发育和块茎生产的差异。在不同年份进行了两次田间试验，种植来自相同基因型的真种子和预发芽幼苗块茎的移植物，同时控制其单位面积的茎密度。对各个主茎的茎分枝和生物量分配对茎密度的响应进行量化，然后评估这些响应对作物性能的影响。在两种繁殖体类型的单个主茎上，较高的茎密度会降低分枝发育，减少地上和地下的分枝数量，导致地上分枝分布向较低的分枝顺序转变，并导致块茎尺寸较小。然而，这种分枝反应在真正种子生长的植物中比在幼苗块茎生长的植物中更强。在作物水平上，不同繁殖体类型在冠层持续时间、块茎数量、块茎大小分布和商品产量方面存在显着差异，但没有茎密度影响。 我们的结果强调了繁殖体类型之间的分枝差异及其对作物发育和块茎产量的影响，因为不存在茎密度的影响。繁殖体类型效应可归因于繁殖体类型在分枝控制、生长习性和源库关系方面的内在差异。这些影响与马铃薯杂交育种相关，需要进一步研究。管理实践是造成分枝和产量形成逐年差异的部分原因，这凸显了管理实践对杂交马铃薯生产的重要性。