Improvements in wheat tillering in dry-land farming systems can be achieved by reducing soil water loss by straw mulching and enhancing the capability of wheat roots to capture soil water and N. However, the effects of the application of maize straw mulching in combination with uniconazole application on wheat tillering is not yet investigated. Field experiments were conducted during 2017–2018 (dry, 167 mm) and 2018–2019 (favorable, 222 mm) to investigate the combined effects of uniconazole (0 and 10 mg kg^-1) and maize straw mulching (0 and 7500 kg ha^-1) on soil water and root distribution, phytohormone signal transduction, total N uptake, plant N nutrition, tillering capability, and the expression of critical genes and metabolites in response to wheat tillering. Compared with no mulch control, straw mulching combined with uniconazole application increased soil moisture content and root length in the 0–20 cm soil layer and thereby increased total N uptake. Owing to allometric increases in aboveground N content and plant dry mass, uniconazole application combined with straw mulching increased the dry mass per kg N uptake and N nutrition index in the tillering and stem extension stages. Improved N nutrition index led to higher tiller emergence rate and tiller occurrence rate of first primary tillers and thus increased the number of fertile spikes and grain yield. Multi-omics integration analysis revealed that the increased tillering capability was associated with abscisic acid and gibberellic acid-mediated phenylpropanoid biosynthesis and glycerophospholipid metabolism because of their critical roles in lignin biosynthesis and the maintenance of cell membrane integrity in tiller node cells. The collective results indicate that maize straw mulching combined with uniconazole application improved the capability of wheat roots to capture soil moisture and N in addition to increasing lignin biosynthesis, ultimately enhancing tillering capability and grain yield of dryland winter wheat.

可以通过秸秆覆盖减少土壤水分流失和提高小麦根系捕获土壤水分和氮的能力来改善旱地耕作系统中的小麦分蘖。但是，玉米秸秆覆盖与烯效唑联合应用的效果尚未研究在小麦分蘖上的应用。在 2017-2018 年（干燥，167 毫米）和 2018-2019 年（有利，222 毫米）期间进行了田间试验，以研究烯效唑（0 和 10 mg kg ^-1）和玉米秸秆覆盖（0 和 7500 kg ha ^-1) 对土壤水分和根系分布、植物激素信号转导、总氮吸收、植物氮营养、分蘖能力以及响应小麦分蘖的关键基因和代谢物的表达。与不覆盖控制相比，秸秆覆盖结合烯效唑施用增加了 0-20 cm 土层的土壤水分含量和根长，从而增加了总氮的吸收。由于地上氮含量和植物干质量的异速增长，在分蘖和茎伸阶段施用烯效唑配合秸秆覆盖提高了每千克氮吸收的干质量和氮营养指数。提高氮素营养指标可提高分蘖出苗率和初生分蘖分蘖发生率，从而增加可育穗数和粮食产量。多组学整合分析表明，增加的分蘖能力与脱落酸和赤霉酸介导的苯丙烷类生物合成和甘油磷脂代谢有关，因为它们在木质素生物合成和维持分蘖节细胞中的细胞膜完整性中起关键作用。综合结果表明，玉米秸秆覆盖结合烯效唑施用除了增加木质素生物合成外，还提高了小麦根系捕获土壤水分和氮的能力，最终提高了旱地冬小麦的分蘖能力和产量。