Department of Agronomy, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran.
Department of Agronomy, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran.
J Plant Physiol. 2022 Feb;269:153614. doi: 10.1016/j.jplph.2021.153614. Epub 2021 Dec 28.
High temperature stress (HTS) imposes secondary dormancy (SD) also known as thermo-dormancy in many seeds. Priming by soil moisture however, may improve germination though under HTS it may compromise seed longevity. Knowledge of how HTS and priming affect dormancy status/viability loss of a particular crop seed species is essential in agriculture. Accordingly, control non-primed and hydro-primed seeds from Dk-xpower and Traper rapeseed cultivars with low and high potential for SD induction, respectively, were compared for germination behavior, response to GA and some phytohormone effectors under HTS. HTS reduced germination in non-primed Dk-xpower and Traper seeds mainly through the induction of thermo-inhibition/death and thermo-dormancy, respectively. Under HTS, GA application reduced thermo-dormancy in favor of thermo-inhibition only in Traper but the GA inhibitor paclobutrazol intensified thermo-dormancy in both cultivars. The ABA inhibitor, fluridone also reduced thermo-dormancy in favor of thermo-inhibition only in Traper. Thus, under HTS, GA biosynthesis is determinant in seed thermo-dormancy/thermo-inhibition dynamics. Hydropriming improved germination under HTS through reduced thermo-inhibition/death (Dk-xpower) and thermo-dormancy (Traper). Here, GA application increased death and compromised germination mainly in Dk-xpower. Paclubutrazol application however, increased thermo-dormancy by compromising thermo-inhibition/death in Traper. Overall, hydro-priming weakened seed phytohormonal germination responses. Controlled deterioration resulted in decreased longevity of hydro-primed seeds but induced SD in non-primed Traper seeds. Thus, down-regulation of GA biosynthesis may control differential induction of SD in rapeseed seeds under HTS while hydro-priming stimulates seed germination possibly through overcoming limitations in GA biosynthesis. The agricultural importance of these findings at the ecosystem scale is discussed.
高温胁迫（HTS）会在许多种子中引发次生休眠（SD），也称为热休眠。然而，通过土壤水分进行引发处理可能会改善种子的发芽率，但在 HTS 下，它可能会损害种子的活力。了解 HTS 和引发处理如何影响特定作物种子休眠状态/活力丧失，对于农业来说至关重要。因此，比较了具有低和高 SD 诱导潜力的 Dk-xpower 和 Traper 油菜品种的非引发和水引发种子，以研究它们在 HTS 下的发芽行为、对 GA 和一些植物激素效应物的反应。HTS 降低了非引发的 Dk-xpower 和 Traper 种子的发芽率，主要是通过分别诱导热抑制/死亡和热休眠。在 HTS 下，GA 处理减少了 Traper 中的热休眠，有利于热抑制，但 GA 抑制剂多效唑在两个品种中都加剧了热休眠。ABA 抑制剂氟啶酮也仅在 Traper 中减少了热休眠，有利于热抑制。因此，在 HTS 下，GA 生物合成是种子热休眠/热抑制动力学的决定因素。水引发通过减少热抑制/死亡（Dk-xpower）和热休眠（Traper）来提高 HTS 下的发芽率。在这里，GA 处理增加了死亡并损害了主要在 Dk-xpower 中的发芽。然而，多效唑的应用通过损害 Traper 中的热抑制/死亡来增加热休眠。总体而言，水引发削弱了种子的植物激素发芽反应。受控劣化导致水引发种子的活力降低，但非引发 Traper 种子的 SD 诱导。因此，GA 生物合成的下调可能控制 HTS 下油菜种子中 SD 的差异诱导，而水引发可能通过克服 GA 生物合成的限制来刺激种子发芽。讨论了这些在生态系统尺度上的发现的农业重要性。
