基于稳定同位素示踪的不同覆砂厚度下枣树水分利用策略

Water utilization strategy of Ziziphus jujuba under different sand cover thicknesses based on stable isotope tracing

干旱区覆砂条件显著影响土壤水分状况,进而影响植被对土壤水分的吸收和利用。然而,对于枣树(Ziziphus jujuba)在不同覆砂条件下的吸水策略及其对输入水的动态响应仍知之甚少。该研究于2023年5月利用氢氧稳定同位素方法结合贝叶斯混合模型(MixSIAR)研究了枣树在不同覆砂厚度下的水分利用策略及其对输入水的响应。结果表明:不覆砂样地在灌溉后第2天出现土壤含水量(SWC)峰值,覆砂5 cm的样地在灌溉后第4天出现峰值,覆砂10和15 cm的样地在灌溉后第6天出现峰值,覆砂显著提高了SWC,增强了土壤的保水性。不覆砂样地的氧稳定同位素比值(δ^(18)O)和氢稳定同位素比值(δ^(2)H)分别为-5.4‰--2.2‰和-76.1‰--61.0‰,覆砂样地的δ^(18)O和δ^(2)H分别为-5.6‰--3.0‰和-61.0‰--75.7‰。灌溉后第2、4、6天,0-10 cm土层不覆砂样地枣树水分利用比例(16.2%、9.1%、10.0%)相较覆砂5、10、15 cm样地(73.0%、54.5%、37.0%;49.0%、46.2%、22.8%;27.1%、36.1%、21.4%)稳定且覆砂措施增加了枣树对0-10 cm土壤水的利用,即枣树对深层土壤水的利用存在滞后效应。以上结果说明了覆砂措施能够有效提高土壤的保水性,影响植物水分利用策略,有利于植物适应当地的干旱条件以及应对其他的环境变化。

Aims Sand cover conditions in arid zones significantly affect soil water status,which in turn affects the utilization of soil water by vegetation.However,little is known about the water uptake strategies of Ziziphus jujuba under different sand cover conditions and its dynamic response to input water.Methods In this study,the water utilization strategies of Z.jujuba under different sand cover thicknesses and their responses to input water were investigated using the hydroxide stable isotope method combined with a Bayesian mixed model(MixSIAR).Important findings We found that the peak of soil water content(SWC)appeared on the 2nd day after irrigation in the non-sand-covered sample plots,on the 4th day after irrigation in the 5 cm sand-covered sample plots,and on the 6th day after irrigation in the 10 and 15 cm sand-covered sample plots.Sand cover significantly increased the SWC,and enhanced the water retention of the soil.The oxygen stable isotope composition(δ^(18)O)and hydrogen stable isotope composition(δ^(2)H)were-5.4‰--2.2‰and-76.1‰--61.0‰in the non-sand-covered sample plots,and-5.6‰--3.0‰and-61.0‰--75.7‰in the sand-covered sample plots,respectively.The 2nd,4th,and 6th day after irrigation,the percentage of water utilization by Z.jujuba in the 0-10 cm soil layer without sand cover(16.2%,9.1%,10.0%)was stable compared with that in the 5,10,15 cm sand-covered sample plots(73.0%,54.5%,37.0%;49.0%,46.2%,22.8%;27.1%,36.1%,21.4%)and sand-covering measures increased the date palm’s water utilization of the 0-10 cm soil water.The sand mulching measures increased the utilization of 0-10 cm soil water by Z.jujuba,i.e.there was a lag in the utilization of deep soil water by Z.jujuba.The above results show that sand mulching can effectively improve the water retention of soil and influence the water utilization strategy of plants,which has implications for the adaptation of plants to local drought conditions and other environmental changes.