The structural deficit of water resources in Mediterranean areas forces us to search for new sources of water for irrigation as a mandatory requirement for a sustainable agriculture. However, given their critical role in soil fertility, the impacts of irrigation in soil microbial communities must be carefully considered alongside the crop responses. Here, we evaluate the impacts of irrigation with water from different origins in the soil microbial community and on the tree physiology and fruit yield in a Mediterranean mandarin agroecosystem. Two sources of water for irrigation were considered: i) fresh water, with an electrical conductivity (EC) of 1.2 dS m⁻¹, from the Tajo-Segura canal (transfer water, TW); and ii) reclaimed water (EC = 3.4 dS m⁻¹) from a wastewater treatment plant (RW). Further, the two types of water were applied using two different regimes: control irrigation (C), to fully satisfy the crop water requirements (100% ET_c), and regulated deficit irrigation (RDI), in which the trees received half the amount of water applied to the C trees (50% ET_c) during the second stage of fruit development. In the case of TW, RDI increased bacterial biomass, and urease and β-glucosidase activities in soil. In contrast, in the case of RW, RDI did not increase bacterial biomass in comparison to control (RW-C). Irrigation with RW caused a reduction in yield in comparison to TW treatments. The combined evaluation of the plant and soil responses to different irrigation strategies is essential in water-limited Mediterranean areas used to grow citrus crops that require less water and nutrients than other crops. Further, this crop can be favored by the use of low to moderate vigorous rootstocks. Our results demonstrate that RDI does not have a drastic negative impacts on crop yield when RW is used, and that there may be some positive effects in soil microbial communities when TW is used for irrigation.

地中海地区水资源的结构性短缺迫使我们寻找新的灌溉水源，这是可持续农业的强制性要求。但是，考虑到它们在土壤肥力中的关键作用，必须结合作物的反应仔细考虑灌溉对土壤微生物群落的影响。在这里，我们评估了土壤微生物群落中不同来源的灌溉用水对地中海柑桔农业生态系统中树木生理和果实产量的影响。考虑了两种灌溉水源：i）来自Tajo-Segura运河的淡水（电导率（EC）为1.2 dS m ^-1）（转移水，TW）；和ii）中水（EC = 3.4 dS m ^-1）来自废水处理厂（RW）。此外，使用两种不同的方式施用了两种类型的水：控制灌溉（C）以完全满足作物的需水量（100％ET _c）和调节性亏缺灌溉（RDI），其中树木的吸收量为一半的水加到C树木（50％ET _ç）在果实发育的第二阶段。在TW的情况下，RDI增加了土壤中的细菌生物量以及脲酶和β-葡萄糖苷酶的活性。相反，在RW的情况下，与对照（RW-C）相比，RDI不会增加细菌生物量。与TW处理相比，RW灌溉导致产量下降。在用水有限的地中海地区种植柑橘类作物时，对植物和土壤对不同灌溉策略的反应进行综合评估至关重要，因为柑橘类作物所需的水分和养分比其他作物少。此外，可通过使用低至中等强度的砧木来促进这种作物的生长。我们的结果表明，当使用RW时，RDI不会对作物产量产生严重的负面影响，而当使用TW进行灌溉时，对土壤微生物群落可能会有一些积极影响。