The identification of soybean genotypes tolerant to soil compaction makes it possible to reduce productivity loss under stress conditions. Added to this, the prior selection of these genotypes will result in greater assertiveness in the positioning of cultivars in the field. Thus, the objective was to evaluate the susceptibility of soybean genotypes to compaction in greenhouse and field conditions; verify which characteristics of seedlings under high resistance to root penetration are correlated with crop production in compacted soil; and to validate the substrate mechanical impedance method for evaluating the susceptibility of plant genotypes to soil compaction. Seeds of 20 genotypes were sown in a substrate mechanical impedance system under controlled conditions. The characteristics evaluated were total root length, total root surface area, mean root diameter, total root volume, taproot length, shoot length, root dry matter and seedling shoot dry matter. In the field experiment, half of the planting area was compacted, constituting two treatments, soil with and without compaction. The percentage of seedling emergence, initial plant height, stem diameter, number of nodes, internode length, number of lateral branches, shoot dry matter, final plant height, absolute and relative growth rate, number of pods, weight of 100 seeds and grain yield. In addition, the number of days between soybean sowing until plant flowering and grain harvest was recorded according to genotype and soil compaction level. In a controlled environment, genotypes tolerant to soil compaction show greater plasticity of root characteristics and smaller alterations in the shoot of seedlings. In the field, these genotypes show smaller reductions in growth rate, height, number of pods and grain yield. The shoot dry matter and the root dry matter of soybean seedlings in a mechanical impedance system present a positive and negative correlation, respectively, with soybean yield in compacted soil, indicating that the genetically determined susceptibility to soil compaction stress was similar throughout ontogenesis. The substrate mechanical impedance system used to evaluate the performance of soybean seedlings under stress, facilitates the decision‐making in breeding programs focused on identifying genotypes expressing soil compaction tolerance.

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土壤压实下大豆基因型的幼苗表现及产量

耐土壤板结的大豆基因型的鉴定使得减少胁迫条件下生产力损失成为可能。除此之外，对这些基因型的事先选择将使品种在田间的定位更加自信。因此，目的是评估大豆基因型在温室和田间条件下对压实的敏感性；验证根系穿透高抗性下的幼苗的哪些特征与压实土壤中的作物产量相关；并验证用于评估植物基因型对土壤压实敏感性的基质机械阻抗方法。在受控条件下将 20 种基因型的种子播种在基质机械阻抗系统中。评估的特征是总根长度、总根表面积、平均根直径、总根体积、主根长度、芽长度、根干物质和幼苗芽干物质。田间试验中，种植面积的一半被压实，分为土壤压实和不压实两种处理。出苗率、初株高、茎粗、节数、节间长、侧枝数、地上部干物质、最终株高、绝对生长率、相对生长率、荚数、百粒重、籽粒产量。此外，根据基因型和土壤压实程度记录大豆播种至植物开花和谷物收获之间的天数。在受控环境中，耐受土壤压实的基因型表现出更大的根部特征可塑性和更小的幼苗芽变化。在田间，这些基因型在生长速度、高度、豆荚数量和谷物产量方面表现出较小的降低。机械阻抗系统中大豆幼苗的地上部干物质和根干物质分别与压实土壤中的大豆产量呈正相关和负相关，这表明遗传决定的对土壤压实胁迫的敏感性在整个个体发育过程中是相似的。用于评估大豆幼苗在胁迫下的表现的基质机械阻抗系统有助于育种计划的决策，重点是识别表达土壤压实耐受性的基因型。