Early senescence in the conventional pattern of wheat production is widespread, leading to decline in potential for increased and stabilized yield. Straw returning could effectively improve soil quality and extend the growth period of wheat. However, the response mechanism of straw returning in delaying leaves senescence and increasing crop productivity by regulating the internal physiological and biochemical processes of leaves is not clear. A field experiment was conducted in northwest China in 2013 (the data used in the text from 2021–2023) with four straw returning patterns: no tillage with straw mulching (NTSM), no tillage with straw standing (NTSS), conventional tillage with straw returning (CTS), and conventional tillage with straw removing (CT, the control). The antioxidant enzyme activities, cellular osmotic contents, endogenous hormones contents, stay-green capability of wheat leaves, photosynthetic source, and crop yield were investigated and analyzed. We found that no tillage with straw mulching (NTSM and NTSS) could effectively enhance the antioxidant and cell osmoregulation capabilities of wheat leaves during the grain filling process. Compared to CT, the SOD activity of NTSM and NTSS increased by 24.9–28.2 % and 18.6–20.4 %, respectively. Soluble protein content increased by 37.3–43.2 % and 25.2–57.1 %, and proline content increased by 37.3–78.4 % and 26.5–31.4 %. However, malondialdehyde content decreased by 20.3–21.4 % and 19.2–23.2 %. It was evident that the NTSM treatment provided a solid physiological foundation for delaying leaves senescence. NTSM could also help to maintain the homeostasis of endogenous hormones in wheat leaves during the grain filling period. Compared to CT, the contents of zeatin, salicylic acid, and jasmonic acid of NTSM increased by 23.3–27.2 %, 18.5–22.0 %, and 15.2–15.3 %, while abscisic acid content of NTSM decreased by 9.4–10.2 %. Based on physiological changes within the leaves, NTSM and NTSS reduced stay-green of leaves before 45 d post-emergence by 20.6–20.9 % and 17.5–17.8 % compared to CT. After 45 d post-emergence, NTSM and NTSS increased stay-green of leaves by 21.9–23.0 % and 17.0–19.1 % over CT. Thus, the grain yield of NTSM was 15.0–22.2 % and 9.0–11.3 % higher than that with CT and CTS, primarily due to the synchronous increase in ear number and thousand grain weight. Therefore, no tillage with straw mulching promoted the mobilization of antioxidant and cellular osmoregulatory responses, optimized endogenous hormones signaling, and maintained higher photosynthesis source and stay-green during the grain filling stage, thus delaying leaves senescence and increasing crop productivity in arid irrigated areas.

中文翻译：

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通过优化秸秆还田模式延缓小麦叶片衰老来提高作物生产力


传统小麦生产模式普遍存在早衰现象，导致增产稳产潜力下降。秸秆还田可以有效改善土壤质量，延长小麦生育期。但秸秆还田通过调节叶片内部生理生化过程延缓叶片衰老、提高作物产量的响应机制尚不清楚。 2013年在西北地区进行田间试验（文中使用2021-2023年的数据），采用秸秆覆盖免耕（NTSM）、秸秆直立免耕（NTSS）、常规秸秆还田四种秸秆还田模式。还田（CTS）和常规耕作（CT，对照）。对小麦叶片的抗氧化酶活性、细胞渗透压含量、内源激素含量、保绿能力、光合来源和作物产量进行了调查和分析。我们发现免耕秸秆覆盖（NTSM和NTSS）可以有效增强灌浆过程中小麦叶片的抗氧化和细胞渗透调节能力。与CT相比，NTSM和NTSS的SOD活性分别增加了24.9-28.2%和18.6-20.4%。可溶性蛋白含量分别增加37.3-43.2%和25.2-57.1%，脯氨酸含量分别增加37.3-78.4%和26.5-31.4%。然而，丙二醛含量下降了 20.3-21.4% 和 19.2-23.2%。显然，NTSM处理为延缓叶片衰老提供了坚实的生理基础。 NTSM 还可以帮助维持灌浆期小麦叶片内源激素的稳态。 与CT相比，NTSM的玉米素、水杨酸和茉莉酸含量增加了23.3%~27.2%、18.5%~22.0%和15.2%~15.3%，而脱落酸含量降低了9.4%~10.2%。根据叶片内部的生理变化，与 CT 相比，NTSM 和 NTSS 在出苗后 45 d 之前使叶片的保绿率降低了 20.6-20.9% 和 17.5-17.8%。出苗后 45 天后，NTSM 和 NTSS 的叶片保绿率比 CT 分别提高了 21.9-23.0% 和 17.0-19.1%。因此，NTSM的籽粒产量比CT和CTS分别提高15.0%~22.2%和9.0%~11.3%，这主要是由于穗数和千粒重的同步增加。因此，免耕秸秆覆盖促进了抗氧化和细胞渗透调节反应的调动，优化了内源激素信号，在灌浆期保持较高的光合作用来源和保持绿色，从而延缓了干旱灌区的叶片衰老，提高了作物生产力。