Long-term excessive application of mineral fertilizer has led to soil acidification and phosphorus(P) accumulation, increasing the risk of P loss and environmental pollution, and cessation of fertilization is widely c...Long-term excessive application of mineral fertilizer has led to soil acidification and phosphorus(P) accumulation, increasing the risk of P loss and environmental pollution, and cessation of fertilization is widely considered as a cost-effective management strategy to relieve this situation;however, how such cessation influences P speciation and concentrations in a bulk soil and colloidal fractions and whether decreasing P concentration might maintain soil fertility remain unclear. In this study, the effects of long-term fertilization(ca. 40 years) and short-term cessation of fertilization(ca. 16 months) on inorganic, organic,and colloidal P in lime concretion black soil were investigated using P sequential fractionation and31P nuclear magnetic resonance spectroscopy. After long-term fertilization, available P, dicalcium phosphate, iron-bound P, orthophosphate monoesters, and orthophosphate diesters increased significantly, but soil p H decreased by ca. 2.8 units, indicating that long-term fertilization caused soil acidification and P accumulation and changed P speciation markedly. In contrast, short-term fertilization cessation increased soil p H by ca. 0.8 units and slightly reduced available and inorganic P. Available P after fertilization cessation was 22.9–29.8 mg kg-1, which was still sufficient to satisfy crop growth requirements. Additionally, fertilization cessation increased the proportions of fine colloids(100–450 nm, including nontronite and some amorphous iron oxides) and drove a significant release of iron/aluminum oxide nanoparticles(1–100 nm) and associated P with orthophosphate and pyrophosphate species. In summary, short-term fertilization cessation effectively alleviated soil acidification and inorganic P accumulation, while concomitantly maintaining soil P fertility and improving the potential mobilization of P associated with microparticles.展开更多
文摘蛋白磷酸酶2C(protein phosphatase 2C,PP2Cs)家族是植物细胞去除磷酸化蛋白中磷酸基团的重要蛋白磷酸酶。拟南芥含有80多个编码PP2Cs的基因,然而大部分成员在植物抗逆反应中的功能仍有待研究。本文发现拟南芥PP2C31(At2g40860)基因的表达受高盐抑制,其T-DNA插入突变体(pp2c31-1突变体和pp2c31-2突变体)表现出对高盐胁迫的耐受性且Na+含量较低。实时定量PCR(quantitative real time-PCR,qRT-PCR)分析发现,PP2C31基因在植物体各组织均有表达;亚细胞定位结果显示PP2C31蛋白定位于细胞质和细胞核中。利用脱落酸合成抑制剂和外源脱落酸处理发现,突变体植株的高盐耐受性和PP2C31基因的表达均不受脱落酸的影响。研究结果表明:PP2C31蛋白是拟南芥响应高盐胁迫的一个非脱落酸依赖的负调控组分。
基金supported by the National Natural Science Foundation of China (No. 41907063)the Foundation of Modern Agricultural Innovation Center, Henan Institute of Sun Yat-sen University, China (No. N2021-002)。
文摘Long-term excessive application of mineral fertilizer has led to soil acidification and phosphorus(P) accumulation, increasing the risk of P loss and environmental pollution, and cessation of fertilization is widely considered as a cost-effective management strategy to relieve this situation;however, how such cessation influences P speciation and concentrations in a bulk soil and colloidal fractions and whether decreasing P concentration might maintain soil fertility remain unclear. In this study, the effects of long-term fertilization(ca. 40 years) and short-term cessation of fertilization(ca. 16 months) on inorganic, organic,and colloidal P in lime concretion black soil were investigated using P sequential fractionation and31P nuclear magnetic resonance spectroscopy. After long-term fertilization, available P, dicalcium phosphate, iron-bound P, orthophosphate monoesters, and orthophosphate diesters increased significantly, but soil p H decreased by ca. 2.8 units, indicating that long-term fertilization caused soil acidification and P accumulation and changed P speciation markedly. In contrast, short-term fertilization cessation increased soil p H by ca. 0.8 units and slightly reduced available and inorganic P. Available P after fertilization cessation was 22.9–29.8 mg kg-1, which was still sufficient to satisfy crop growth requirements. Additionally, fertilization cessation increased the proportions of fine colloids(100–450 nm, including nontronite and some amorphous iron oxides) and drove a significant release of iron/aluminum oxide nanoparticles(1–100 nm) and associated P with orthophosphate and pyrophosphate species. In summary, short-term fertilization cessation effectively alleviated soil acidification and inorganic P accumulation, while concomitantly maintaining soil P fertility and improving the potential mobilization of P associated with microparticles.
