The availability of nitrogen (N) contained in crop residues for a following crop may vary with cultivar, depending on root traits and the interaction between roots and soil. We used a pot experiment to investigate the effects of six spring wheat (Triticum aestivum L.) cultivars (three old varieties introduced before mid last century and three modern varieties) and N fertilization on the ability of wheat to acquire N from maize (Zea mays L.) straw added to soil. Wheat was grown in a soil where ¹⁵N‐labeled maize straw had been incorporated with or without N fertilization. Higher grain yield in three modern and one old cultivar was ascribed to preferred allocation of photosynthate to aboveground plant parts and from vegetative organs to grains. Root biomass, root length density and root surface area were all smaller in modern than in old cultivars at both anthesis and maturity. Root mean diameter was generally similar between modern and old cultivars at anthesis but was greater in modern than in old cultivars at maturity. There were cultivar differences in N uptake from incorporated maize straw and the other N sources (soil and fertilizer). However, these differences were not related to variation in the measured root parameters among the six cultivars. At anthesis, total N uptake efficiencies by roots (total N uptake per root weight or root length) were greater in modern than in old cultivars within each fertilization level. At maturity, averaged over fertilization levels, the total N uptake efficiencies by roots were 292−336 mg N g⁻¹ roots or 3.2−4.0 mg N m⁻¹ roots for three modern cultivars, in contrast to 132−213 mg N g⁻¹ roots or 0.93−1.6 mg N m⁻¹ roots for three old cultivars. Fertilization enhanced the utilization of N from maize straw by all cultivars, but root N uptake efficiencies were less affected. We concluded that modern spring wheat cultivars had higher root N uptake efficiency than old cultivars.

中文翻译：

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现代小麦品种比老品种具有更高的根系氮吸收效率。

后续作物的作物残茬中所含氮（N）的可用性可能因品种而异，具体取决于根的性状以及根与土壤之间的相互作用。我们用盆栽试验研究6个春小麦（的影响小麦品种对小麦从玉米获取n中的能力和施氮（三个旧品种中期上世纪三个现代品种前出台）L.）（玉米L.）将秸秆添加到土壤中。小麦生长在¹⁵N标记的玉米秸秆已经或没有施氮。在三个现代品种和一个旧品种中，较高的谷物产量归因于光合产物优先分配给地上植物部分以及营养器官和谷物。在开花期和成熟期，现代品种的根系生物量，根系长度密度和根系表面积均比旧品种小。花期，现代品种和老品种的根均直径通常相似，但在成熟时，现代品种的根平均直径要大于老品种。掺入的玉米秸秆和其他氮源（土壤和肥料）的氮吸收品种存在差异。但是，这些差异与六个品种间测得的根系参数的变化无关。在花期，在每个施肥水平上，现代根系的总氮吸收效率（每根根重或根长的总氮吸收量）比老品种高。成熟期，按施肥水平平均，根的总氮吸收效率为292−336 mg N g^-1根或3.2-4.0毫克N-米^-1根为三个现代栽培品种，而相比之下，132-213毫克N-克^-1根或0.93-1.6毫克N-米^-1根为三米旧的栽培品种。施肥提高了所有品种对玉米秸秆氮的利用率，但对根系氮吸收效率的影响较小。我们得出结论，现代春小麦品种比老品种具有更高的根系氮吸收效率。