Differential effects of nitrate and ammonium supply on nodule initiation, development, and distribution on roots of pea (Pisum sativum)
Differential effects of nitrate and ammonium supply on nodule initiation, development, and distribution on roots of pea (Pisum sativum)
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DOI：
10.1139/b06-027
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发表时间：
2006-06-01
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影响因子：
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通讯作者：
Vessey, J. Kevin
中科院分区：
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作者：
Bollman, Mavis I.;Vessey, J. Kevin
低浓度的静态铵态氮对豌豆（Pisum sativum L.）而不是硝酸盐，在某些情况下，实际上可能会刺激排卵。进行了两个实验，以评估供应两种形式的矿质氮，单独和组合，对根瘤的开始，根瘤的发展，根瘤之间的初级和侧（二级）根，第三根的发展，和N-2固定豌豆的分布的影响。豌豆植株在无矿质氮（零氮）、NO3-（0.5mmol中心点L-1）、NH 4+（0.5mmol中心点L-1）或NO3-（0.25mmol中心点L-1）加NH 4+（0.25mmol中心点L-1）的水培中接种后生长长达24 ad。每天监测硝酸盐和铵的浓度，并通过连续自动添加储备溶液保持相对恒定。豌豆植株积累了最多的总干物质（DM）和总氮时，提供了硝酸盐加铵的组合，但有最低的根瘤DM和来自大气的氮的百分比。全株结瘤率（每株结瘤）和DM-特异结瘤率（结瘤中心点g（-1）根DM）分别为2.3和2.4倍，在豌豆植株中接受NH 4+在0.5 mmol中心点L-1比那些提供NO3-在0.5 mmol中心点L-1。NO3-在0.25 mmol center dot L-1 + NH 4+在0.25 mmol center dot L-1的植物的同化反应更类似于那些只接受硝酸盐比只有铵的植物，表明当这两种形式的矿物氮都是植物，硝酸盐对同化反应的主导作用。对实验期间结核原基和结核发育阶段的评估表明，硝酸盐不仅降低了结核形成的程度，而且降低了结核发育的速度。显微观察表明，与铵态氮处理相比，硝态氮处理对DM特异性同化的负面影响在初生根和侧根上是一致的。对侧根的次生根形成和三次根发育的定量分析表明，铵离子对次生根的刺激作用是专一的，对三次根发育的影响不同。这项研究表明，第一次，当两种形式的矿物N在相同的浓度下，豌豆的施肥反应的影响更多的硝酸盐比铵和硝酸盐和铵对第三根的发生和发展的影响是不同的施肥。
Low, static concentrations of ammonium have less negative effects on nodulation of pea (Pisum sativum L.) than nitrate and in some cases may actually stimulate nodulation. Two experiments were carried out to assess the effects of supplying both forms of mineral N, separately and in combination, on nodule initiation, nodule development, nodule distribution between primary and lateral (secondary) roots, tertiary root development, and N-2 fixation in pea. Pea plants were grown for up to 24ad after inoculation in hydroponic culture with no mineral N (zero N), NO3- (0.5 mmol center dot L-1), NH4+ (0.5 mmol center dot L-1), or NO3- (0.25 mmol center dot L-1) plus NH4+ (0.25 mmol center dot L-1). Concentrations of nitrate and ammonium were monitored on a daily basis and held relatively constant by continuous, automatic additions of stock solutions. Pea plants accumulated the most total dry mass (DM) and total N when supplied with the combination of nitrate plus ammonium but had the lowest nodule DM and percentage of nitrogen derived from the atmosphere. Whole-plant nodulation (nodules per plant) and DM-specific nodulation (nodules center dot g(-1) root DM) were 2.3- and 2.4-fold greater, respectively, in pea plants receiving NH4+ at 0.5 mmol center dot L-1 than in those supplied with NO3- at 0.5 mmol center dot L-1. The nodulation responses of plants receiving NO3- at 0.25 mmol center dot L-1 plus NH4+ at 0.25 mmol center dot L-1 were more similar to those of plants receiving only nitrate than only ammonium, indicating that when both forms of mineral N are available to plants, nitrate has a predominant effect on the nodulation response. Assessment of the stage of development of nodule primordia and nodules during the time course of the experiments indicated that nitrate not only decreased the degree of nodule initiation but also the rate at which those nodules developed. Microscopic observations indicated that the more negative effects of the nitrate treatment on DM-specific nodulation as compared with the ammonium treatment were consistent on both the primary and lateral roots. Quantification of nodulation and tertiary root development on lateral roots indicated that the stimulating effects of ammonium were specific to nodulation; the effects on tertiary root development were different. The study demonstrates for the first time that when both forms of mineral N are available at equal concentrations, the nodulation response in pea is influenced more by nitrate than by ammonium and that the effects of nitrate and ammonium on tertiary root initiation and development are unlike those on nodulation.