Influence of arbuscular mycorrhizae and phosphorus fertilization on growth, nodulation and N-2 fixation (N-15) in Medicago sativa at four salinity levels
Influence of arbuscular mycorrhizae and phosphorus fertilization on growth, nodulation and N-2 fixation (N-15) in Medicago sativa at four salinity levels
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DOI：
10.1007/s003740050212
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发表时间：
1997-01-01
影响因子：
6.5
通讯作者：
ElAtrash, F
中科院分区：
文献类型：
--
作者：
Azcon, R;ElAtrash, F
研究了丛枝菌根（AM）真菌Glomus mosseae对紫花苜蓿（+苜蓿根瘤菌）抗盐胁迫的作用。土壤中的可溶性P（四个水平），菌根接种和与植物生长，营养和感染参数的盐度之间的相互作用进行了评估。盐胁迫是通过连续灌溉具有四种浓度的三种盐（NaCl、CaCl 2和MgCl 2）的盐水来诱导的。加入N-15标记的硫酸铵，以提供在中等至高盐度水平下N-2固定的定量估计。N和P的浓度和根瘤形成的植物有效的P或菌根接种物在土壤中的量增加，一般下降的溶液培养的盐度从中等到高的水平。菌根接种保护植物免受盐胁迫更有效地比任何数量的植物有效磷在土壤中，特别是在最高的盐度水平（43.5 dS m（-1））。接种菌根对土壤干物质和养分的影响与添加150 mg P kg（-1）的效果相当。然而，最高盐溶液测定（43.5 dS m（-1））影响更严重的植物补充磷比那些与菌根接种物。这种抑盐效果是1.5（生物量），1.4（N）和1.5（P）倍以上的植物供应可溶性磷酸盐比AM接种。除了P介导的机制之外，AM对盐度的保护作用也必须参与其中。使用的N-15的方法允许测定N-2固定的影响，不同的P应用相比，菌根接种。根瘤的形成和功能（N-2固定）之间缺乏相关性的证据在菌根接种的植物。尽管菌根接种植物中每个根瘤的活性降低，但测定的N含量表明，共生状态的植物中N的获得最高。接种AM后，植株对N、P的吸收增加，而对Ca、Mg的吸收减少。因此，P/Ca比和阳离子/阴离子平衡一般改变菌根治疗。因此，这项研究证实了以前的研究结果，AM殖民植物有可选的和替代的机制，以满足他们的营养需求，并保持其生理状态，在压力的情况下，在受干扰的生态系统。
The role of an isolate of the arbuscular mycorrhizal (AM) fungus Glomus mosseae in the protection of Medicago sativa (+Rhizobium meliloti) against salt stress induced by the addition of increasing levels of soluble salts was studied. The interactions between soluble P in soil (four levels), mycorrhizal inoculum and degree of salinity in relation to plant growth, nutrition and infective parameters were evaluated. Salt stress was induced by sequential irrigation with saline water having four concentra- tions of three salts (NaCl, CaCl2, and MgCl2). N-15-labelled ammonium sulphate was added to provide a quantitative estimate of N-2 fixation under moderate to high salinity levels. N and P concentration and nodule formation increased with the amount of plant-available P or mycorrhizal inoculum in the soil and generally declined as the salinity in the solution culture increased from a moderate to a high level. The mycorrhizal inoculation protected the plants from salt stress more efficiently than any amount of plant-available P in soil, particularly at the highest salinity level applied (43.5 dS m(-1)). Mycorrhizal inoculation matched the effect on dry matter and nutrition of the addition in the soil of 150 mg P kg(-1). Nevertheless the highest saline solution assayed (43.5 dS m(-1)) affected more severely plants supplemented with phosphorus than those with the addition of mycorrhizal inoculum. Such a saline-depressing effect was 1.5 (biomass), 1.4 (N) and 1.5 (P) times higher in plants supplied with soluble phosphate than with AM inoculum. Mechanisms beyond those mediated by P must be involved in the AM-protective effect against salinity. The N-15 methodology used allowed the determination of N-2 fixation as influenced by different P applications compared to mycorrhizal inoculation. A lack of correlation between nodule formation and function (N-2 fixation) was evidenced in mycorrhizal-inoculated plants. In spite of the reduced activity per nodule in mycorrhizal-inoculated plants, the N contents determined indicated the highest acquisition of N occurred in plants with the symbiotic status. Moreover, N and P uptake increased while Ca and Mg decreased in AM-inoculated plants. Thus P/Ca ratios and cation/anion balance in general were altered in mycorrhizal treatments. This study therefore confirms previous findings that AM-colonized plants have optional and alternative mechanisms available to satisfy their nutritive requirements and to maintain their physiological status in stress situations and in disturbed ecosystems.