Microelement Research Center, Huazhong Agricultural University, Wuhan 430070, China; College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
Sci Total Environ. 2022 Nov 25;849:157858. doi: 10.1016/j.scitotenv.2022.157858. Epub 2022 Aug 4.
Application of Zn fertilizers to agricultural field is a simple and effective way for farmers to manage Zn deficient stress in soils to avoid yield lose. Although a synergistic effect of Zn on N transformation in soil has been reported, the mechanism is not fully understood yet. In this study, we planted rice in soils with different combinations of Zn and N supply, and analyzed the plant growth and N uptake, the N transformation, microbial communities, enzyme activities and gene expression levels in rhizosphere soil to reveal the underlying mechanism. Results showed that Zn application promoted the rice growth and N uptake, increased the soil alkali-hydrolyzed N and NH, but decreased NO and inhibited NH volatilization from the rhizosphere soil under optimal N condition. Zn supply significantly increased the relative abundances of Sphingomonas, Gaiella, subgroup_6, and Gemmatimonas, but decreased nitrosifying bacteria Ellin6067; while increased saprophytic fungi Schizothecium and Mortierella, but decreased pathogenic fungi Gaeumannomyces, Acremonium, Curvularia, and Fusarium in the rhizosphere soil under optimal N condition. Meanwhile, Zn application elevated the activities of protease, cellulase and dehydrogenase, and up-regulated the expression levels of napA, nirS, cnorB, and qnorB genes involved in the denitrification process in rice rhizosphere soil under optimal N condition. These results indicated Zn application could facilitate the soil N transformation and improved its availability by modifying both bacterial and fungal communities, and altering the soil enzyme activities and functional gene expression levels, ultimately promoted the N uptake and biomass of rice plant. However, this synergistic effect of Zn on rice growth, N uptake and soil N transformation strongly depended on the external N conditions, as no significant changes were observed under high N condition. Our results indicated that Zn co-fertilized with appropriate application of N is a useful strategy to improve the N bioavailability in rice rhizosphere soil and enhance the N uptake in rice plant.
在农业领域施用锌肥是农民管理土壤缺锌胁迫以避免减产的一种简单而有效的方法。尽管已经报道了锌对土壤氮转化的协同作用，但该机制尚未完全了解。在这项研究中，我们在不同组合的锌和氮供应的土壤中种植水稻，并分析了植物生长和氮吸收、氮转化、微生物群落、根际土壤酶活性和基因表达水平，以揭示潜在的机制。结果表明，锌的施用促进了水稻的生长和氮的吸收，增加了土壤碱解氮和 NH₄⁺，但减少了硝态氮并抑制了根际土壤中 NH₄⁺的挥发。在最佳氮条件下，锌的供应显著增加了鞘氨醇单胞菌、盖伊氏菌、第 6 亚群和芽单胞菌的相对丰度，但降低了硝化细菌 Ellin6067；同时增加了腐生真菌石蒜和莫蒂埃利亚菌，但降低了根际土壤中的致病性真菌球毛壳菌、枝顶孢属、旋孢腔菌和镰刀菌。同时，在最佳氮条件下，锌的施用提高了蛋白酶、纤维素酶和脱氢酶的活性，并上调了参与反硝化过程的 napA、nirS、cnorB 和 qnorB 基因的表达水平。这些结果表明，锌的施用可以通过改变细菌和真菌群落，改变土壤酶活性和功能基因表达水平，促进土壤氮转化，提高其有效性，从而促进水稻根系土壤氮的吸收和生物量。然而，这种锌对水稻生长、氮吸收和土壤氮转化的协同作用强烈依赖于外部氮条件，在高氮条件下没有观察到显著变化。我们的研究结果表明，锌与适量氮的共施肥是提高水稻根际土壤氮生物有效性和增强水稻氮吸收的有效策略。
