Wu Zhengfeng, Tang Zhaohui, Yu Tianyi, Zhang Jiancheng, Zheng Yongmei, Yang Jishun, Wu Yue, Sun Qiqi
Shandong Peanut Research Institute, Shandong Academy of Agricultural Sciences, Qingdao, China.
Institute of Crop Germplasm Resources, Shandong Academy of Agricultural Sciences, Jinan, China.
Front Plant Sci. 2023 Mar 3;14:1109860. doi: 10.3389/fpls.2023.1109860. eCollection 2023.
Crops influence both soil microbial communities and soil organic carbon (SOC) cycling through rhizosphere processes, yet their responses to nitrogen (N) fertilization have not been well investigated under continuous monoculture.
In this study, rhizosphere soil microbial communities from a 5-year continuous mono-cropped peanut land were examined using Illumina HighSeq sequencing, with an N fertilization gradient that included 0 (N0), 60 (N60), 120 (N120) and 180 (N180) kg hm. Soil respiration rate ( ) and its temperature sensitivity ( ) were determined, with soil carbon-acquiring enzyme activities assayed.
The obtained results showed that with N fertilization, soil mineral N (N) was highly increased and the soil C/N ratio was decreased; yields were unchanged, but root biomass was stimulated only at N120. The activities of β-1,4-glucosidase and polyphenol oxidase were reduced across application rates, but that of β-1,4-cellobiohydrolase was increased only at N120. Bacterial alpha diversity was unchanged, but fungal richness and diversity were increased at N60 and N120. For bacterial groups, the relative abundance of Acidobacteria was reduced, while those of Alphaproteobacteria and Gammaproteobacteria were increased at N60 and N120. For fungal members, the pathogenic Sordariomycetes was inhibited, but the saprotrophic Agaricomycetes was promoted, regardless of N fertilization rates. RDA identified different factors driving the variations in bacterial (root biomass) and fungal (N) community composition. N fertilization increased slightly at N60 and significantly at N120, mainly through the promotion of cellulose-related microbes, and decreased slightly at N180, likely due to carbon limitation. N fertilization reduced microbial biomass carbon (MBC) at N60, N120 and N180, decreased SOC at N120 and N180, and suppressed dissolved organic carbon (DOC) at N180. In addition, the unchanged may be a joint result of several mechanisms that counteracted each other. These results are of critical importance for assessing the sustainability of continuously monocultured ecosystems, especially when confronting global climate change.
作物通过根际过程影响土壤微生物群落和土壤有机碳（SOC）循环，然而在连续单作条件下它们对氮肥的响应尚未得到充分研究。
在本研究中，使用Illumina HighSeq测序技术对一块连续5年单作花生的土地的根际土壤微生物群落进行了检测，设置了包括0（N0）、60（N60）、120（N120）和180（N180）kg hm的氮肥梯度。测定了土壤呼吸速率（ ）及其温度敏感性（ ），并分析了土壤碳获取酶活性。
所得结果表明，随着氮肥施用，土壤矿质氮（N）显著增加，土壤碳氮比降低；产量未变，但仅在N120时根生物量受到刺激。β-1,4-葡萄糖苷酶和多酚氧化酶的活性在各施用量下均降低，但β-1,4-纤维二糖水解酶的活性仅在N120时增加。细菌α多样性未变，但在N60和N120时真菌丰富度和多样性增加。对于细菌类群，酸杆菌门的相对丰度降低，而在N60和N120时变形菌门的α-变形菌纲和γ-变形菌纲的相对丰度增加。对于真菌成员，无论氮肥施用量如何，致病的粪壳菌纲均受到抑制，但腐生的伞菌纲得到促进。冗余分析（RDA）确定了驱动细菌（根生物量）和真菌（N）群落组成变化的不同因素。氮肥在N60时使 略有增加，在N120时显著增加，主要是通过促进与纤维素相关的微生物，而在N180时 略有降低，可能是由于碳限制。氮肥在N60、N120和N180时降低了微生物生物量碳（MBC），在N120和N180时降低了SOC，并在N180时抑制了溶解有机碳（DOC）。此外， 未变可能是几种相互抵消的机制共同作用的结果。这些结果对于评估连续单作生态系统的可持续性至关重要，尤其是在面对全球气候变化时。
