高效亲和的花生寄主植物-根瘤菌株组合

本文针对栽培花生，从大、小共生体双方研究了寄主植物－根瘤菌株组合的亲和性。结果指出：（１）在温室水培盆栽条件下，用菌株１４７－３接种的寄主植物结瘤、固氮能力育成品种〉普通型；（２）血清学鉴定出５个不同血清型菌株，其竞争力或回收率与寄主品种、根瘤菌株和土著菌数密切相关；（３）在温室与田间条件下，不同花生寄主一根瘤菌株组合存在着广谱或特异共生亲和性与非亲和性的差异，并鉴定出高效、广谱亲和的品种徐州６－     

大豆品种—根瘤菌株最佳组合筛选试验

在5个大豆品种[Glycine max(L.)Merr.]上分别接种12个大豆根瘤菌菌株[其中1株快生型(Rhizobium Japonicum)其余11株均为慢生型(Bradyrhizobium japonicum)]和一个土壤上清液样品;接种后28天和48天分别测定各处理的单株结瘤数、单株根瘤鲜重、单株茎叶干重、单株茎叶含氮量以及28天至48天单株茎叶的氮积累量。结果表明,不同根瘤菌菌株对上述5个指标的影响,不论在28天或48天都有差异(P=0.01);而不同大豆品种对上述5个指标的影响,28天时无差异而48天都表现出差异(P=0.01);并且28天和48天的茎叶含氮量有品种×菌株相互作用效应外,而其他指标均没有品种×菌株相互作用效应。参试菌株以22—10、USDA123,Tal377,E84,USDA110固氮效率较高,大豆品种以绥83—495在结瘤、固氮方面表现较优良。     

抗春雷霉素大豆根瘤菌突变株的诱变及其生物固氮特性的分析

根瘤菌与豆科植物共生可以固定大量的氮。根瘤菌剂接种豆科作物是一项普遍推广应用、有效的农业技术。但由于大量土著根瘤菌的存在，产生竞争障碍，降低了接种菌剂的占瘤率。大多数的土著根瘤菌对春雷霉素敏感，因此接种抗春雷霉素的高效结瘤固氮根瘤菌，并用春雷霉素处理种子，可抑制土著根瘤菌，提高接种菌剂的占瘤率，从而达到高结瘤、高固氮和提高产量的目的。本文将探讨诱变对根瘤菌抗春雷霉素突变的作用，并对获得的抗性突变株的生物固氮特性进行分析。     

胡枝子根瘤菌优良菌种筛选及应用

介绍胡枝子根瘤菌的生理生化特性，共生固氮性能及连续三年的草场接种效果试验。人工接种根瘤菌可以使胡枝子早结瘤、多结瘤。是提高胡枝子共生固氮作用、增加产草量的有效措施。     

一株大豆根系来源的不同类型土著B.japonicum菌株的共生特性

本文对未接种的大豆单株根系来源的不同类型Ｂ．ｊａｐｏｎｉｃｕｍ菌株共生效率进行了评价。结果表明，供试１２个菌株与６个大豆品种都形成有效共生，但不同菌株，品种和菌株－品种组合间均存在极显著差异，表现共生亲和多样性。菌株结瘤竞争力越强，其共生固氮效率越高。     

吉林省不同类型土壤中大豆根瘤菌的分布及人工接种的效果

土壤中的根瘤菌与豆类植物共生形成了共生固氮体系,为大豆生长发育提供了一部分氮素营养。根瘤的形成与固氮强度又决定于土壤中根瘤细菌的有无、数量和结瘤固氮活力。     

山西省费氏中华根瘤菌数量分布及特性探析

费氏中华根瘤菌(Sinorhzobium fredii)的区域分布与抗逆特性比较明显,在山西省石灰性土壤环境条件下,其数量分布达5100~5100000个/g(土),约占土著大豆根瘤菌的99.4%。该菌群与当地晋豆品种的自然结瘤率达80%以上,是山西省高感土著大豆根瘤菌的主要类群和资源优势,而与美国大豆“Osumi”等品种不亲和,几乎不结瘤。供试高效费氏中华根瘤菌株与当地“晋豆19”与“晋豆20”等主栽品种具有较好的结瘤固N效果。费氏中华根瘤菌的产酸性能有利于在山西省碱性土壤中生存,其活化根际养分效应与结瘤固N效果可能同等重要。     

四川高效大豆根瘤菌的筛选及初步应用研究

采用无氮水培、盆栽、田间区组试验,从采集自四川33个市县35个采样点分离获得的70个大豆根瘤菌株中,筛选与四川主栽大豆品种 贡选1号 匹配性最佳的根瘤菌。对第一批分离自21个市县23个采样点的52个菌株进行无氮水培实验,其结瘤能力和共生固氮能力表明,S8、S22、S36、S46、S55、S65菌株与贡选1号共生匹配性好。用6个菌株进行的盆栽试验结果表明,S36、S8菌株与 贡选1号 匹配性较佳。将第二批分离自四川另外12个市县的12个采样点的18个菌株进行第二次水培实验,以S8、S36和CK分别作为阳性和阴性对照,结果表明接种S151、S152、S150、S149菌株的植株鲜重和干重均极显著高于CK,且高于阳性对照（S8、S36）。结合盆栽和第二次水培实验结果选择S152、S151、S150、S149、S8进行田间试验,以不接种为对照,结果显示,接种S152、S150菌株的大豆产量分别比CK显著增加33.5%和18.5%,且显著高于其它三个供试菌株S151、S149和S8接种处理。为此筛选出与四川主栽大豆品种贡选1号共生匹配性最佳的菌株是S152、S150。     

安徽省北部大豆根瘤菌的分离,血清学分析及田间自然结瘤调查

对安徽省北部分离的２７株快生大豆根瘤菌和３８株慢生大豆根瘤菌的血清学分析及田间自然结瘤的血清学调查表明：００５血清型系安徽北部夏大豆产区占据优势的血清型，１８组样品和再现频率为１００％；３６株分离物中２６株属００５血清型，占总分离物的７２．５％。２０４８血清型出现频率为８３．３％；在３组样品中占瘤率达４１－５１。６％。２１７血清型占瘤率普遍低于１６％。讨论了自然结瘤调查中采样地点，大豆品种和土壤类     

抗药性根瘤菌基因工程菌的构建与应用

用三亲本杂交的方法将外源抗药性质粒导入到高效固氮的根瘤菌 Tal377中,外源质粒在 Tal377中能正常表达,但不影响其原有的固氮结瘤能力。利用此抗药性根瘤菌所携带的抗药性,在接种此根瘤菌的同时结合施加一定浓度的抗菌素,抗药性根瘤菌与出发菌株相比表现出一定程度地提高其结瘤固氮能力和占瘤率。     

Nodulation competition among Bradyrhizobium japonicum strains as influenced by rhizosphere bacteria and iron availability

Summary Bacteria isolated from the root zones of field-grown soybean plants [Glycine max (L.) Merr.] were examined in a series of glasshouse experiments for an ability to affect nodulation competition among three strains of Bradyrhizobium japonicum (USDA 31, USDA 110, and USDA 123). Inocula applied at planting contained competing strains of B. japonicum with or without one of eleven isolates of rhizosphere bacteria. Tap-root nodules were harvested 28 days after planting, and nodule occupancies were determined for the bradyrhizobia strains originally applied. Under conditions of low iron availability, five isolates (four Pseudomonas spp. plus one Serratia sp.) caused significant changes in nodule occupancy relative to the corresponding control which was not inoculated with rhizosphere bacteria. During subsequent glasshouse experiments designed to verify and further characterize these effects, three fluorescent Pseudomonas spp. consistently altered nodulation competition among certain combinations of bradyrhizobia strains when the rooting medium did not contain added iron. This alteration typically reflected enhanced nodulation by USDA 110. Two of these isolates produced similar, although less pronounced, effects when ferric hydroxide was added to the rooting medium. The results suggest that certain rhizosphere bacteria, particularly fluorescent Pseudomonas spp., can affect nodulation competition among strains of R. japonicum. An additional implication is that iron availability may be an important factor modifying interactions involving the soybean plant, B. japonicum, and associated microorganisms in the host rhizosphere.Paper No. 10648 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695-7601, USA     

Selection of type A and type B strains for improving symbiotic effectiveness on non-Rj and Rj4 genotype soybean varieties

The selection of effective rhizobia for higher efficiency nitrogen fixation is one of the most important steps for inoculant production. Therefore, this experiment was conducted to select the most effective type A and type B strains for specific Rj-gene harboring soybean varieties and to test the symbiotic effectiveness of selected strains on different Rj-gene harboring soybean varieties. Screening experiments using the specific soybean varieties were done with a completely randomized design and three replications in this study. Evaluation of the effective Myanmar Bradyrhizobium strains for plant growth, nodulation and N₂ fixation were studied in pot experiments using sterilized vermiculite in the Phytotron (controlled-environmental condition). Then, a pot experiment was conducted using Futsukaichi soil in the screen house (natural environmental condition). The N₂ fixation ability of soybean was evaluated by acetylene reduction activity (ARA) and the relative ureide index method. In the first screening experiment, type A and type B strains with higher nitrogen fixation and proper nodulation on their respective soybean cultivars were selected for the next screening. In the second screening, Bradyrhizobium elkanii AHY3-1 (type A), Bradyrhizobium japonicum SAY3-7 (type A), B. elkanii BLY3-8 (type B) and B. japonicum SAY3-10 (type B) isolates, which showed higher nitrogen fixation and nodulation in Yezin-3 (Rj₄) and Yezin-6 (non-Rj), were selected for the next experiment. In the third screening experiment, SAY3-7 and BLY3-8, which had higher nitrogen fixing potential and proper nodulation, were selected as effective isolates. These two isolates were compatible with non-Rj and Rj₄ soybean varieties for nodulation and nitrogen fixation. Based on the results of the screening experiment, these two strains were tested for their symbiotic efficacy in Futsukaichi soil. This study shows that inoculation treatment of SAY3-7 and BLY3-8 significantly increased plant growth, nodulation, and N₂ fixation at the V6, R3.5 and R8 stages in Yezin-3 (Rj₄) and/or Yezin-6 (non-Rj), and the seed yield at R8 stage, in Yezin-3 (Rj₄) and Yezin-6 (non-Rj) soybean varieties compared with the control treatment. It can be concluded that SAY3-7 and BLY3-8 are suitable for inoculant production because of their higher nitrogen fixation ability, proper nodulation and better productivity of Myanmar soybean cultivars.     

Soybean preference for Bradyrhizobium japonicum for modulation

Abstract

Caldwell and Vest (1968) planted soybeans (Glycine max L. Merr.) with various genotypes at Beltsville, USA, without inoculating them with Bradyrhizobium japonicum, and showed that soybeans preferred certain serotypes of rhizobial strains for nodulation. Recently, the authors have reported that soybeans carrying nodulation-conditioning genes preferred appropriate strains showing specific behavior for nodulation (Ishizuka et al. 1991). For instance, nodulation of soybean cv. Hardee which carries the nodulation-conditioning genes, Rj ₂ and Rj ₃, does not occur with B. japonicum USDA122, USDA33, Is-1, etc. Nodulation of cv. Hill which carries the Rj ₄ gene, does not occur with B. japonicum USDA61, Is-21, etc. while A62-2 which carries a recessive gene rj ₁, does not nodulate with almost any of the strains of B. japonicum. Therefore, the B. japonicum strains can be classified into three nodulation types based on the compatibility with these Rj-cultivars, that is, type A strains which effectively nodulated both Rj ₂ Rj ₃-cultivars and Rj ₄-ones, type B strains which did not nodulate the Rj ₂ Rj ₃-cultivars and type C strains which did not nodulate the Rj ₄-cultivars. When the nodulation types of the isolates from nodules of field-grown soybeans were examined, it was suggested that the Rj ₂ Rj ₃-cultivars and Rj ₄-cultivars preferred the type C and type B strains, respectively (Ishizuka et al. 1991).     

Nodulation of Rj-soybean varieties with Rhizobium fredii USDA 193 under limited supply of nutrients

The compatibility between rhizobia and host plants for nodulation was determined based on the genetic and physiological properties of both symbionts. It has been observed that soybean varieties carrying the Rj-gene were not nodulated effectively by certain strains or groups of rhizobia. Soybeans carrying the Rj ₂-gene, Rj ₂-varieties, were found to nodule ineffectively by the rhizobial strains belonging to the 3-24-44 and 122 serogroups (Caldwell 1966). In the same way, Rj ₃- and Rj ₄-varieties were found to nodule ineffectively by strains USDA 33 (Vest 1970) and USDA 61 (Vest and Caldwell 1972), respectively.     

Rhizobiophage effects on nodulation,nitrogen fixation,and yield of field-grown soybeans (Glycine max L. Merr.)

Summary Previous laboratory and greenhouse studies have shown that phages significantly reduce soil populations of homologous rhizobia. Reductions in nodulation and N₂ fixation have also been observed. The purpose of the current study was to examine the effect of a phage specific ofBradyrhizobium japonicum USDA 117 on nodulation, nodule occupancy, N₂ fixation and soybean growth and yield under field conditions. The phage was inoculated in combination withB. japonicum USDA 117 and/orB. japonicum USDA 110 (resistant strain) into a rhizobia-free sandy loam soil and planted toGlycine max (L.) Merr. Williams. When the phage was applied to soil inoculated withB. japonicum USDA 117 alone, significant reductions in nodule weight and number, shoot weight, foliar N, nitrogenase activity, and seed index were observed. When, however, the soil also contained the non-homologous strain,B. japonicum USDA 110, no significant effects on any of these parameters were found. Nodule occupancy by competing strains ofB. japonicum USDA 110 and USDA 117 was also affected by the phage. In soil which did not contain the phage, 46% and 44% of the identified nodules were occupied by USDA 110 and 117, respectively. When the phage was present in the soil, nodule occupancy byB. japonicum USDA 117 was reduced to 23%, while occupancy byB. japonicum USDA 110 was increased to 71%. These results suggest that nodulation by selected strains of rhizobia can be restricted and nodulation by more effective, inoculated strains can be increased through the introduction of a homologous phage to soils.     

Field performance of three Bradyrhizobium japonicum strains with two soybean (Glycine max. L.) cultivars

Summary A field experiment was condutced in a clay loam soil to study the performance of three Bradyrhizobium japonicum strains; USDA 110, USDA 138 and TAL 379, in relation to their N₂-fixing potential and competitiveness on two soybean cultivars (Clark and Calland). Inoculation of soybean cultivars with these strains, either singly or in combination, induced significant increases in plant dry weight, N₂ fixation and seed yields. However, no significant differences were found between the rhizobial strains and/or their mixtures in N₂ fixation and increased seed yield for both cultivars. The two soybean cultivars gave similar responses to inoculation. No significant differences in seed yield were observed between Clark and Calland cultivars. The interaction between inoculant strain and soybean cultivar was not significant. The competition between strains for nodulation was assessed. Strain USDA 110 was the most competitive, followed by USDA 138. Strain TAL 379 was always less competitive on both cultivars. The incidence of double-strain occupancy of nodules varied from 8% to 40%.     

Diversity and geographical distribution of indigenous soybean-nodulating bradyrhizobia in Japan

Abstract

Genetic diversity and distribution of indigenous soybean-nodulating bradyrhizobia in Japan were investigated based on restriction fragment length polymorphism analysis of PCR product (PCR-RFLP) analysis of the 16S?23S rDNA internal transcribed spacer (ITS) region using Bradyrhizobium USDA strains as reference strains. Soil samples were collected from five field sites in Hokkaido, Fukushima, Kyoto, Miyazaki and Okinawa in Japan. A total of 300 isolates were derived from three Rj-genotype soybean cultivars, Akishirome (non-Rj), CNS (Rj ₂ Rj ₃) and Fukuyutaka (Rj ₄), and five field site combinations. The PCR products of the ITS region were digested with HaeIII, HhaI, MspI and XspI. Electrophoresed patterns were analyzed for phylogenetic relationship using Bradyrhizobium reference strains. Results revealed 22 RFLP patterns and 11 clusters. The RFLP patterns of the seven clusters were similar or identical to Bradyrhizobium japonicum USDA 6, 38, 110, 115, 123 and Bradyrhizobium elkanii USDA 76 and 94. Four minor clusters were independent from the clusters of the reference strains. The isolation ratio revealed the major clusters at each field site. These results suggested that major clusters of indigenous bradyrhizobia might be in the order Bj123, Bj38, Bj110, Bj6 and Be76 from the northern to southern regions in Japan.     

Effect of soil physical properties on soybean nodulation and N2 fixation at the early growth stage in heavy soil field in Hachirougata Polder,Japan

We studied the effect of the soil physical properties on soybean nodulation and N₂ fixation in the heavy soil of an upland field (UF) and an upland field converted from a paddy field (UCPF) in the Hachirougata polder, Japan. Seeds of the soybean cultivar Ryuho were sown in each field with or without inoculation of Bradyrhizobium japonicum A1017. The soybean plants were sampled at 35 (V3) and 65 (Rl) d after sowing (DAS), and then nodulation and the percentage of N derived from N₂ fixation in the xylem sap were determined. The soil physical properties were different between UF and UCPF, especially the air permeability and soil water regime. Nodule growth was restricted in UCPF irrespective of rhizobial inoculation, though rhizobial infection was not inhibited by the unfavorable soil physical conditions. Soybean plant growth was closely related to the nodule mass and N₂ fixation activity, and the inoculation of a superior rhizobium strain was effective only at 35 DAS. These results indicate that soybean nodulation and N₂ fixation was considerably affected by the physical properties of heavy soil, and that it is important to maintain the N₂ fixation activity and inoculate the soybean plants with a superior rhizobium strain at a later growth stage in order to increase soybean production in heavy soil fields.     

Commercial rhizobial inoculants significantly enhance growth and nitrogen fixation of a promiscuous soybean variety in Kenyan soils

Low effectiveness of native strains remains a limitation to soybean productivity in sub-Saharan Africa; while in other countries commercial inoculants are produced that provide effective strains that stimulate N fixation and growth. An experiment was set up to evaluate the response of a dual purpose promiscuous soybean variety (TGx1740-2F) and a non-promiscuous variety (Nyala) to commercial rhizobium inoculants in soils from central and coastal Kenya. Highest nodulation was observed in some of the treatments with commercial inoculants applied with nodule weights of 4.5 and 1.0 g plant⁻¹ for TGx1740-2F and Nyala, respectively. Average biomass yields of TGx1740-2F (16 g plant⁻¹) were twice as large as of Nyala (7.5 g plant⁻¹) at the podding stage. Nitrogen fixation was higher in TGx1740-2F than in Nyala, and positively affected by a number of commercial inoculants with more than 50% N derived from the atmosphere. Nodule occupancy was 100% on both soybean varieties, indicating that the commercial strains were extremely infective in both of the tested soils. These results showed that commercial strains can be used to inoculate promiscuous soybean and enhance N fixation and yield.     

Effect of nitrogen levels and Rhizobium strains on symbiotic N2 fixation and grain yield of Phaseolus vulgaris L. genotypes in normal and saline-sodic soils

Summary Following screening, selection, characterization, and symbiotic N₂ fixation with 12,5, 25.0, and 40.0 mg N kg^–1 in normal and saline-sodic soils, only two Phaseolus vulgaris genotypes (HUR 137 and VL 63) and two Rhizobium spp. strains (ND 1 and ND 2) produced maximum nodulation, nitrogenase activity, plant N contents, and grain yields in saline-sodic soil, with 12.5 mg N kg^–1, compared with the other strains. However, interactions between strains (USDA 2689, USDA 2674, and ND 5) and genotypes (PDR 14, HUR 15, and HUR 138) were significant and resulted in more nodulation, and greater plant N contents, nitrogenase activity, and grain yields in normal soils with 12.5 mg N kg^–1 compared with salt-tolerant strains. Higher levels of N inhibited nodulation and nitrogenase activity without affecting grain yields. To achieve high crop yields from saline-sodic and normal soils in the plains area, simultaneous selection of favourably interacting symbionts is necessary for N economy, so that bean yields can be increased by the application of an active symbiotic system.