High temperature stress during the reproductive growth stage of wheat (Triticum aestivum L.) can cause extensive yield losses. As the plant hormone auxin is a key regulator of reproductive development, we studied the effect of auxins on grain yield in five wheat lines exposed to moderate heat stress (34–35°C) for 6 h per day for 6 days during early flowering (booting stage to anthesis). ‘CDC Go’, a semi-dwarf (Rht-B1b) cultivar, responded to auxin application (1 µM) by producing higher grain number and yield under control and heat stress conditions. The effect of five different auxins on grain yield in ‘CDC Go’ was dependent on spike developmental stage at application and position within the spike, with 4-Cl-IAA at 1 µM being the most effective auxin treatment. The presence of Rht dwarfing mutant alleles of Rht-B1 and Rht-D1 alone did not increase auxin-induced grain yield when tested in lines isogenic for these alleles. In the field, 4-Cl-IAA (1 µM) increased grain yield by 6%–8% only in ‘CDC Go’, one of six hard red spring wheat cultivars tested over two growing seasons in the western Canadian prairies. When 4-Cl-IAA application increased grain yield and number, the grain protein content was not affected; when it maintained grain yield in plants with lower biomass, grain protein content was reduced. Our field results suggested that both genotype and environment affect auxin-induced enhancement of wheat grain yield. We recommend testing target environments with heat stress as a focus of a breeding programme along with further testing of auxin as a crop enhancement tool.

中文翻译：

---

生长素对改善热应激诱导的小麦（Triticum aestivum L.）籽粒损失的影响

小麦（Triticum aestivum L. ）生殖生长阶段的高温胁迫会导致大量的产量损失。由于植物激素生长素是生殖发育的关键调节剂，我们研究了生长素对早花期间暴露于中等热胁迫（34-35°C）6小时每天6小时的五个小麦品系的谷物产量的影响。开花期）。'CDC Go'，一个半矮人（Rht - B1b) 栽培品种，通过在控制和热应激条件下产生更高的籽粒数和产量来响应生长素应用 (1 µM)。五种不同的生长素对“CDC Go”中谷物产量的影响取决于施用时的穗发育阶段和穗内的位置，1 µM 的 4-Cl-IAA 是最有效的生长素处理。Rht - B1和Rht - D1的Rht矮化突变等位基因的存在当在这些等位基因的等位基因系中进行测试时，单独的植物生长素不会增加生长素诱导的谷物产量。在田间，4-Cl-IAA (1 µM) 仅将“CDC Go”的谷物产量提高了 6%–8%，这是在加拿大西部大草原的两个生长季节中测试的六个硬红春小麦品种之一。施用4-Cl-IAA提高籽粒产量和数量时，籽粒蛋白质含量不受影响；当它在生物量较低的植物中保持谷物产量时，谷物蛋白质含量会降低。我们的田间结果表明，基因型和环境都会影响生长素诱导的小麦籽粒产量增加。我们建议将热应激测试目标环境作为育种计划的重点，同时进一步测试作为作物增强工具的生长素。