气候变化背景下有限供水冬小麦的适宜播期研究
A study on the suitable sowing date of winter wheat with limited water supply under the background of climate change
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摘要: 自工业革命以来, 气候变化加剧导致华北平原中北部冬小麦-夏玉米生长条件发生改变, 调整冬小麦播期为该地区实施“两早-两晚”技术具有重要意义。本试验基于中国科学院栾城农业生态系统试验站2016—2023年限水灌溉条件下冬小麦7个生育期4个播期2个品种的试验数据, 确定以稳产为前提的冬小麦适宜播期及满足适播的热量条件。4个播期分别为当地正常播期(播期1)以及每个播期在上一个播期基础上推迟5~7 d (播期2、3和4)。结果表明, 除‘石优20’外, 冬小麦在播期2后产量明显下降, 播期4与其他3个播期下的产量差异较大, 根据本试验条件适播日期为10月12日—10月24日, 以作物发育基点温度为0 ℃计算的冬前积温和生育期总积温需分别达350和2010 ℃·d。不同播期通过积温影响冬小麦各阶段生育期, 随着播期的推迟, 不同生长阶段(播种—越冬、越冬—拔节、拔节—扬花和扬花—收获)持续时间变化分别为缩短、延长、延长和缩短, 且不同品种对播期的响应不同。晚播冬小麦冬前不具备充分分蘖的气象条件, 在拔节期形成最大群体, 发育进程滞后影响群体数量以及生殖生长持续时间, 从而导致作物减产。冬小麦扬花前生物量增长速率与小麦群体动态变化同步, 若冬末春初遇到高温, 晚播冬小麦能弥补前期生长进程过慢产生的差距。播期对产量三要素产生的影响为: 穗数降低、穗粒数增加和千粒重变化无统计学差异, 晚播冬小麦收获指数高于早播, 籽粒品质随播期推迟存在下降趋势, 但不同品种间存在差异。通过本研究得到以下结论: 在温度升高的气候变化背景下, 冬小麦适宜播种日期可推迟2.6 d, 为夏玉米延长灌浆期晚收获创造条件, 以上为华北平原中北部实施“两早-两晚”技术的决策提供了理论支撑, 为农业发展适应气候变化减轻压力。Abstract: Climate change has intensified since the Industrial Revolution, leading to changes in winter wheat and summer maize growth conditions in the central and northern parts of North China Plain. Modifying the sowing date of winter wheat to implement the “two early-two late” technology in this area is important. Based on the interannual variation in meteorological factors during the growing season of winter wheat from 2016 to 2023 at the Luancheng Agro-Ecosystem Experimental Station of the Chinese Academy of Sciences, this experiment studied the suitable sowing date of winter wheat in the context of climate change. Using field-measured data of four winter wheat cultivars for seven growing seasons from 2016 to 2023 with four sowing dates under limited irrigation from 2016 to 2023, the suitable sowing date and necessary heat conditions for winter wheat were determined to achieve a stable yield. The four sowing dates were normal (sowing date 1) and extended by 5−7 days each for delayed sowing dates (sowing date 2, 3, and 4). The results showed that the yield of winter wheat (excluding SY20) decreased after date 2 and that the yield for date 4 was lower than that for the other three sowing dates. Under the current climate conditions, the suitable sowing date was October 12–24. The thermal time before winter and the total thermal time during the whole growing season should reach 350 and 2010 °C·d, respectively. Different sowing dates affect the duration of the different stages of winter wheat through thermal time. With the delay in the sowing date, the durations of sowing—overwintering, overwintering—jointing, joining—anthesis, and anthesis—maturity were shortened, prolonged, prolonged, and shortened, respectively, and the responses to the sowing date of different cultivars were different. Winter wheat sown late was not capable of sufficient tillering before winter and formed the largest population at the jointing stage. The lag in the development process negatively affected the spike number and reduced the duration of reproductive growth, resulting in reduced crop yield. Before anthesis, the biomass production increase rate of winter wheat was synchronized with the dynamic changes in the community. If high temperatures were encountered in late winter and early spring, the gap caused by the slow growth in the early stages of late-sowing winter wheat could be narrowed. The effects of the sowing date on the three yield elements were as follows: spike number decreased, kernels per spike increased, and no statistically significant difference in the 1000-kernel weight. The harvest index of late-sowing winter wheat was higher than that of early-sowing winter wheat. Grain quality decreased with the delay in the sowing date, but differences existed among the cultivars. In conclusion, the outcome of this study that the suitable sowing date should be postponed under the context of climate change provides theoretical support for the decision to implement the “two early-two late” technology in the central and northern parts of North China Plain and reduces the pressure on agricultural development to adapt to climate change.