Supplemental irrigation (SI) at critical growth stages is a practical way to mitigate water shortage of winter wheat in dryland. However, the yield performance after SI is unstable in different precipitation years. To obtain a better understanding about the applicability of SI in dryland, the utilization efficiency of precipitation and irrigation water (IUE) was divided into 5 sequential ratios: water storage ratio, water consumption ratio, water transpired ratio, transpiration efficiency and harvest index. In this study, those ratios were investigated under four SI methods: no irrigation (W), SI once at jointing (W), SI once at booting (W) and SI twice at jointing and booting (W) throughout four years. Our results showed that water storage ratio was increased under all SI treatments, but water transpired ratio was only significantly increased under W and W, due to their greater development of plant population compared to W. Thus, wheat yield was greatly improved by 7–12 % under W and W than that under W in dry and normal years. However, IUE was significantly decreased under W. Compared with W, W had higher evaporation during the fallow period and lower water consumption ratio. Furthermore, 100–300 cm subsoil water utilization was decreased under W from jointing to harvest time due to the low root length density (RD) in subsoil. Under W, evaporation, subsoil water utilization and RD were not negatively affected and water use efficiency was increased compared to W. Thus, SI once at jointing stage is a more suitable practice in dryland wheat farmland when considering the dual goal of effectively using water while increasing yields under worse precipitation year.

中文翻译：

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不同补灌方式通过改变旱地小麦水分利用过程步骤导致水分利用效率和产量的差异


关键生育期补充灌溉（SI）是缓解旱地冬小麦缺水的实用方法。然而，不同降水年份SI后的产量表现并不稳定。为了更好地了解SI在旱地的适用性，将降水和灌溉水的利用效率（IUE）分为5个序列比：储水比、耗水比、蒸腾水比、蒸腾效率和收获指数。在这项研究中，这些比率在四种 SI 方法下进行了调查：四年内不灌溉 (W)、拔节时浇水一次 (W)、孕穗时浇水一次 (W) 以及拔节和孕穗时浇水两次 (W)。我们的结果表明，所有 SI 处理下的储水率均有所增加，但水分蒸发率仅在 W 和 W 下显着增加，因为与 W 相比，它们的植物群体发育更大。因此，小麦产量大大提高了 7-12旱年和正常年份W 和W 下的% 比W 下的%。但W下IUE显着降低。与W相比，W在休耕期蒸发量较高，耗水率较低。此外，由于底土中的根长密度（RD）较低，从拔节到收获期间，W 处理下 100-300 cm 底土水分利用率降低。在W下，蒸发、底土水利用和RD没有受到负面影响，并且与W相比，水分利用效率有所提高。因此，考虑到有效利用水分和水分的双重目标，在旱地小麦农田中，在拔节期进行SI是更合适的做法。在降水较差的年份提高产量。