不同氮效率水稻生育后期根表和根际土壤硝化特征  

Soil nitrification in root surface and rhizosphere at late growth stages of rice cultivars with different N use efficiency

作　　者：李奕林[1,2] 黄启为[1] 王兴祥[2] 沈其荣[1] 

机构地区：[1]南京农业大学环境与科学学院,南京210095 [2]中国科学院南京土壤研究所,南京210008

出　　处：《生态学报》2009年第2期824-831,共8页Acta Ecologica Sinica

基　　金：国家自然科学基金资助项目(30671234,30771290);江苏省重大攻关项目(BE2005369)

摘　　要：通过田间试验研究了不同氮效率粳稻品种4007(氮高效)和Elio(氮低效)生育后期在N0(0kgNhm-2)、N180(180kgNhm-2)和N300(300kgNhm-2)水平下根表、根际和土体土壤pH值、铵态氮(NH4+-N)和硝态氮(NO3--N)含量、硝化强度和氨氧化细菌(AOB)数量。结果表明无论是齐穗期、灌浆期还是成熟期,根表土壤pH值均显著低于根际和土体土壤。土壤pH值范围在5.95至6.84之间变化。土壤NH4+-N含量随水稻生长显著下降,且随施氮量增加而显著增加。根表土壤NH4+-N有明显亏缺区,且随距水稻根表距离增加,NH4+-N含量逐渐升高。土壤NO3--N含量随水稻生长显著增加,施氮处理均显著高于不施氮处理,但N180和N300处理差异不显著。NO3--N含量表现为根际>土体>根表。水稻根表和根际土壤硝化强度随水稻生长显著下降,而土体土壤硝化强度随时间延长小幅增加。施氮显著提高4007水稻根表土壤在齐穗和收获期硝化强度以及Elio在齐穗期根际硝化强度,但在施氮处理N180和N300中无显著差异。在整个采样期间,土壤硝化强度均表现为根际>根表>土体。水稻根表和根际AOB数量随水稻生长而显著降低,而土体土壤AOB数量无显著变化。例如,根表土壤AOB数量在齐穗期、灌浆期和收获期分别为16.7×105、8.77×105个g-1drysoil和8.01×105个g-1drysoil。根表和根际土壤AOB数量无显著差异,但二者显著高于土体土壤AOB数量。就两个氮效率水稻品种而言,土壤pH值基本无差异。4007土壤NH4+-N含量均显著高于Elio。在齐穗期水稻根表、根际和土体土壤NO3--N含量在N180水平下均表现为Elio显著高于4007。而在灌浆期和收获期,水稻根表、根际和土体土壤则表现为4007显著高于Elio。在所有采样期,两个水稻品种土体土壤硝化强度和AOB数量在3个施氮量下均无显著差异。Elio根表和根际土壤硝化强度和AOB数量在水稻灌浆期之前一直显著高于4007,而在灌浆期之后则Nitrification characteristics in rice rhizosphere were studied using two Japonica rice cultivars with different nitrogen use efficiency （NUE）, 4007 （high NUE） and Elio （low NUE）. We determined pH, ammonium （NH4^＋ -N） and nitrate （NO3^- -N） , nitrification and ammonia- oxidizing bacteria （AOB） abundance in root surface, rhizosphere and bulk soil under the NO （0 kgN hm^-2） , N180 （180 kgN hm^-2） and N300 （300 kgN hm^-2） levels at the late growth stages in the field conditions. The pH values in root surface soil were significantly lower than those in rhizosphere and bulk soil at heading, filling and harvesting stages, ranging from 5.95 to 6.84. NH4^＋ -N concentration decreased but NO3^- -N increased with the plant development. N application increased NH4 ^＋ -N and NO3^- -N concentrations in all soil samples. Depletion sections of both NH4^＋ and NO3^- were found in root surface soil. The NH4^＋ -N concentration increased with increasing distance from the root surface. The maximal NO3^- concentration was in rhizosphere soil, then the bulk soil and the lowest was in root surface soil. Nitrification activities in both root surface and rhizosphere soils significantly decreased with the incubation time, but the reverse was true for the bulk soil. N application improved nitrification activities in root surface soil grown with 4007 both at heading and harvesting stages, and also improved nitrification activity in rhizosphere soil grown with Elio at heading stage. But there was no significant difference between N180 and N300 treatments. The nitrification activity showed such order as rhizosphere 〉 root surface 〉 bulk soil at the whole sampling stages. AOB abundance in both root surface and rhizosphere soils significantly decreased with the incubation time, while those in the bulk soil indicated no difference as the time passed. For example, the AOB abundances in root surface soil at heading, filling and harvesting stages were 16.7 × 10^5, 8.77 × 10^5 and 8.01 × 10^5 g^-1 dr

关 键 词：硝化作用 硝化微生物 氮素利用率 根表土壤 根际土壤 土体土壤 

分 类 号：S511[农业科学—作物学]