Lodging is a major constraint contributing to poor grain yield and quality of wheat (Triticum aestivum L.) worldwide. The use of plant growth regulators is becoming a foremost agro-chemical approach for minimizing the risk of lodging in cereal crops. The present study was conducted to examine the effects of the paclobutrazol application on culm physical strength, lignin content, and lodging resistance of wheat. Wheat seeds were soaked in paclobutrazol at the concentrations of 0 (CK, as control), 200 (PB1), 300 (PB2), and 400 (PB3) mg L-1. Our results showed that paclobutrazol resulted in a dose-dependent decrease of plant height, internode length, and center of gravity height. Paclobutrazol treatments evidently increased the culm diameter, culm filling degree, and wall thickness of basal internodes, resulting in greater stalk-breaking strength and lodging resistance index (CLRI), where their maximum values were obtained with PB1 treatment. In addition, the activities of lignin-related enzymes were improved by paclobutrazol, particularly at low concentration, which increased the lignin accumulation of the basal internodes of wheat, subsequently improving the capability of stalk lodging resistance. Moreover, the correlation analysis revealed significant correlations between stem diameter, culm filling degree, and lignin with stalk bending strength and CLRI. The paclobutrazol concentration ≥ 300 mg L-1 (PB2 and PB3 treatments) showed inhibitive effects on various culm morphological traits. These results suggest that not only the plant height, but also the lignin contents and physical strength of internodes are closely related with the lodging resistance of wheat, and reduction in plant height along with improved culm morphological characteristics and higher lignin accumulation in basal internodes could effectively relieve the risk of lodging.

中文翻译：

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多效唑的应用：通过调节株高，茎的物理强度和木质素的生物合成来诱导小麦抗倒伏性的策略。

寄宿是造成世界范围内小麦（Triticum aestivum L.）小麦单产和品质下降的主要制约因素。植物生长调节剂的使用正成为减少谷物作物倒伏风险的最重要的农业化学方法。本研究旨在研究多效唑对小麦茎秆物理强度，木质素含量和抗倒伏性的影响。将小麦种子以0（CK作为对照），200（PB1），300（PB2）和400（PB3）mg L-1的浓度浸入多效唑中。我们的结果表明多效唑可导致植物高度，节间长度和重心高度的剂量依赖性降低。多效唑的处理明显增加了基节间的茎秆直径，茎秆填充度和壁厚，导致更高的茎断裂强度和抗倒伏指数（CLRI），其中最大值通过PB1处理获得。此外，多效唑可改善木质素相关酶的活性，特别是在低浓度时，可提高小麦基节间木质素的积累，从而提高抗茎秆倒伏能力。此外，相关性分析显示茎直径，茎秆填充度和木质素与秸秆弯曲强度和CLRI之间存在显着相关性。多效唑浓度≥300 mg L-1（PB2和PB3处理）对多种茎秆形态学特征具有抑制作用。这些结果表明，不仅株高，