雷竹林土壤氨氧化微生物对不同肥料的响应

雷竹Phyllostachys violascens林冬季地表覆盖施肥为核心的集约经营技术被广泛推广应用,冬季覆盖以及施肥处理必将对土壤氨氧化微生物群落结构产生影响。为揭示雷竹林覆盖和施肥等集约经营措施对土壤氨氧化微生物的影响,进行了田间试验。设计如下2个试验:试验1为施用等量硝态氮复合肥:m(氮)∶m(五氧化二磷)∶m(氧化钾)=16∶16∶16的对照1(不覆盖)和处理1(覆盖);试验2为覆盖的4个不同肥料处理,分别为对照2(不施肥),处理1,处理2(尿素),处理3(尿素+氯化钾),各处理以含氮量360 kg·hm-2为标准折算成相应的肥料用量,氯化钾与复合肥等钾量折算。应用聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)技术和定量PCR技术分析土壤氨氧化细菌(AOB)和氨氧化古菌(AOA)群落结构多样性和功能基因丰富度。结果表明:不同处理土壤氨氧化细菌和氨氧化古菌有较高比例的共性种类,群落结构尚未发生显著改变;前期未覆盖的对照1与其他前期曾覆盖的所有处理的氨氧化细菌群落结构差异相对较明显,同为前期覆盖的处理3与其他处理又稍有不同;土壤氨氧化细菌多样性为处理1明显高于(P<0.05)处理3;处理3氨氧化细菌和氨氧化古菌的基因的丰度均较高(P<0.05)。综合比较不同处理氨氧化细菌和氨氧化古菌的DGGE条带的多样性以及定量分析得出结论,处理3的氨氧化微生物多样性和功能基因最丰富,处理2最差。建议生产上采用尿素与氯化钾搭配施用,有利于土壤氨氧化微生物的活动和氮素循环利用。

Response of soil ammonia-oxidizing organisms on fertilization and mulch in Phyllostachys violascens stands

 For intensive management of Phyllostachys violascens stands, heavy winter mulching, to increase soil temperature, and winter fertilization are widely used techniques which affect the activity of soil ammonia oxidizing organisms. To understand the effects of mulch and fertilization on ammonia oxidizing bacteria （AOB）and ammonia oxidizing archaea（AOA）communities, two experiments were conducted: 1）with a constant N fertilizer  rate of 360 kg·hm^-2 applied as m（N）∶m（P₂O₅）∶m（K₂O）=16∶16∶16 and treatments（Tr） with mulch （Tr1）and no mulch（ck1）；and 2） with mulch in each treatment and ck，three fertilizer combinations at a constant N rate of 360 kg·hm^-2 ［Tr1（as above）--applied as a compound fertilizer，Treatment 2（Tr2）--applied N as urea，Treatment 3（Tr3）--applied fertilizer as urea and potassium chloride（KCl），and ck2--no fertilizer applied］. The community structure and functional gene abundance of soil AOB and AOA were measured using polymerase chain reaction--denaturing gradient gel electrophoresis（PCR-DGGE） and real-time--polymerase chain reaction （RT-PCR） with the Shannon diversity index being used for analysis. Results showed a majority of common AOB and AOA species represented by bands on DEEG profile were produced from the all treatments. The AOB community structure with no mulch（ck1） was different from the other treatments which received mulch in the winter season, and Tr3 was different from the other mulched treatments. The Shannon diversity index for AOB species with Tr1 was significantly higher（P＜0.05）than Tr3. The higher （P＜0.05）amoA abundance for both AOB and AOA was observed in Tr3. Results from the combination of PCR-DGGE and RT-PCR for both AOA and AOB, showed Tr3 best in species diversity and gene abundance of ammonia oxidizing organisms；whereas，Tr2 was worst. Thus，to sustain the activity of ammonia oxidizing organisms and to improve N recycling，urea in combination with KCl should be applied. ［Ch，3 fig. 2 tab. 28 ref.］