ABSTRACT

Heat stress during the grain filling is one of most critical factors impacting grain yield in winter wheat. In a two-year field experiment, we studied the effects of 24-Epicastasterone and KH₂PO₄ on heat-stressed wheat applied during different times. A completely randomized block design was used with three reagents, that is, 24-Epicastasterone, KH₂PO₄ and H₂O and three spraying times, that is, pre-heat, under-heat and post-heat. Two cultivars, that is, Huaimai 33 and Annong 0711 were subjected to a 7 d post-flowering heat stress using plastic tents. Our study suggests that greater grain weight in heat-stressed plants was achieved through sustaining leaf greenness and higher assimilates supplies to grains. When heat-stressed plants sprayed either with 24-Epicastasterone or KH₂PO₄ could sustain a relatively higher leaf photosynthetic capacity by up-regulating antioxidant enzymes with reduced damage on lipid membranes and leaf chlorophyll. We also found that KH₂PO₄ was relatively more effective in improving leaf physiology and grain yield of heat-stressed plants than 24-Epicastasterone. Further analysis showed that pre-heat or post-heat was more pronounced in protecting plants from heat injury than spraying the plants under heat stress. Thus, spraying KH₂PO₄ either prior to or post stress incidence is recommended to protect wheat crops from terminal heat stress.

摘要

灌浆期热胁迫是影响冬小麦籽粒产量的最关键因素之一。在为期两年的田间试验中，我们研究了24-表蓖麻甾酮和KH ₂ PO ₄对不同时间施用的热胁迫小麦的影响。完全随机区组设计使用三种试剂，即 24-表甾酮、KH ₂ PO ₄和 H ₂O和三个喷涂时间，即预热、欠热和后热。使用塑料帐篷对淮麦 33 和安农 0711 两个品种进行花后 7 天热胁迫。我们的研究表明，通过维持叶子的绿色和更高的谷物同化供应，热胁迫植物的粒重更大。当喷洒 24-表蓖麻甾酮或 KH ₂ PO ₄的热胁迫植物可以通过上调抗氧化酶来维持相对较高的叶片光合能力，同时减少对脂质膜和叶片叶绿素的损害。我们还发现 KH ₂ PO ₄与 24-表蓖麻甾酮相比，在改善热胁迫植物的叶片生理和籽粒产量方面相对更有效。进一步分析表明，预热或后热在保护植物免受热害方面比在热胁迫下喷洒植物更显着。因此，建议在胁迫发生之前或之后喷洒 KH ₂ PO _{4以保护小麦作物免受终端热胁迫。}