慢生型花生根瘤菌培养基优化研究

研究了慢生型花生根瘤菌sdlx-04菌株在YMA、BSE、TY、SM 4种培养基中的生长情况并应用正交试验L9(34)对根瘤菌进行了培养基优化研究。结果表明,根瘤菌sdlx-04菌株在BSE培养基上生长最快,本试验条件下,适于sdlx-04菌株生长的优化培养基为以葡萄糖为碳源的培养基。     

Symbiotic efficiency and compatibility of native rhizobia in northern Thailand with different soybean cultivars

Symbiotic efficiency and compatibility of 81 isolates of native bradyrhizobia from irrigated areas in northern Thailand with four soybean cultivars and one cowpea cultivar were evaluated under laboratory conditions. Effectiveness and / or compatibility of the tested isolates were compared with those of a standard strain (Bradyrhizobium japonicum CB 1809) by using plants grown on plastic seed bags. Effectiveness of the isolates was also estimated using uninoculated control plants grown in a nitrogen-free solution. Nodulation of a wide range of host plants by the majority of the tested isolates was observed, which agreed well with the results of our previous field experiment (Shutsrirung et al. 2002: Soil Sci. Plant Nutr., 48, 491–499). Up to 75% of the tested isolates induced a higher growth efficiency than that of the uninoculated control in association with one of the tested cultivars, Black soybean. Comparision with uninoculated control plants, enable to estimate the proportion of the tested isolates leading to effective growth promotion (E + e) of each cultivar, namely, Black soybean (local Thai cultivar), 75%; Cowpea, 82%; SJ5 (commercial Thai cultivar), 33%; Bragg (US cultivar), 33%; and Improved Pelican (US cultivar), 9%. These results indicated that although isolates with a high infectiveness with both “Asian-type” and “US-type” soybeans could be found, a high frequency of isolates leading to inefficient nodules was observed in the US cultivar, suggesting the presence of genetic differences in the soybean cultivars that express high-preference (efficient nodules) or low-preference (inefficient nodules) for a certain group of tested isolates. Based on the results of this laboratory experiment together with our previous field experiment, native rhizobial populations in the irrigated area of northern Thailand could be separated into three groups; Group 1: rhizobium strains showing a high effectiveness with only Asian cultivars, Group 2: strains showing a high effectiveness with only US origin cultivars, and Group 3: strains showing a high effectiveness with both Asian and US origin cultivars. The majority of the native rhizobial populations belonged to Group 1. The isolates in Group 3 may display a high potential for manipulating useful rhizobial inoculant.     

胶质类芽孢杆菌与慢生大豆根瘤菌复合接种效果评价

【目的】胶质类芽孢杆菌（Paenibacillus mucilaginosus）和慢生大豆根瘤菌（Bradyrhizobium japonicum）作为微生物肥料的生产菌种,凭借其良好的解钾溶磷促生效果及共生固氮功能,广泛应用于农业生产,目前对其单一菌种促生或固氮效果及机理已有较多报道。本研究旨在开展胶质类芽孢杆菌与慢生大豆根瘤菌复合接种研究,评价其接种效果,并对作用机理初探,为开发功能复合型微生物菌剂,丰富微生物肥料产品提供技术支持。【方法】田间小区试验在山东省泰安市农业科学院邱家店科研基地进行。设T1（空白对照）,T2（胶质类芽孢杆菌3016单接种）,T3（慢生大豆根瘤菌5136单接种）,T4（胶质类芽孢杆菌3016和慢生大豆根瘤菌5136复合接种）和T5（常规施肥）5个处理,4次重复。分析大豆播种前（0 d）、花荚期（50 d）、鼓粒期（80 d）和成熟期（110 d）土壤肥力、土壤微生物区系的变化及对大豆品质的影响。【结果】接种胶质类芽孢杆菌和大豆根瘤菌的各处理均能提高单株籽粒重、产量和收获指数,其中以复合接种处理效果最优,分别高于对照处理12.8%、9.3%和41.0%,且差异显著;该处理下,大豆茎叶和籽粒的氮、磷、钾含量都具有较高水平,特别是籽粒钾、茎叶氮和茎叶磷,分别比对照提高了5.7%、9.3%和38.5%,复合接种能显著提高大豆产量和品质。在土壤肥力方面,施用胶质类芽孢杆菌、根瘤菌和化学肥料对土壤全氮、速效磷、速效钾和有机质均有一定程度的改善和提高,其中以复合接种效果最佳,成熟期各指标分别比对照提高了16.5%、43.7%、8.5%和15.5%;相对于化学肥料,施用胶质类芽孢杆菌和慢生大豆根瘤菌的各处理,对土壤肥力提高效果更有持久性且对土壤pH影响更小,其中复合接种能显著改善土壤肥力。除此之外,复合接种还能够丰富土壤微生物群落多样性,提高微生物总量,尤其是增加细菌和放线菌数量,抑制真菌增长,有利于土壤实现由“真菌型”向“细菌型”的良性转变。典型对应分析结果表明,pH和速效钾是引起土壤细菌群落变化的主控环境因子。【结论】胶质类芽孢杆菌和慢生大豆根瘤菌复合接种不仅能够改善大豆品质、增加产量,还能提高土壤肥力、改善土壤微生物区系,是一种节本增效的施肥方式,具有良好的应用前景。     

celB基因标记法研究酸性土花生接种及施钼效果

以缺钼酸性紫色土为供试土壤做盆栽试验,选用celB标记的三株慢生型花生根瘤菌celB3-5、celB3-7、celB4-5接种天府9号花生。通过标记根瘤菌形成的根瘤能与检测试剂产生颜色反应的特征,检测施钼及施不同浓度的钼对花生-根瘤菌有效性和竞争性的影响。结果表明,缺钼酸性紫色土上单施钼、单接种、接种配合施钼均能促进花生与根瘤菌的共生固氮效应和竞争结瘤能力,但接种配合施钼的效果最好,单接种的效果次之,单施钼的效果差。单施钼时,0.4%的钼酸铵拌种效果好,接种根瘤菌时,0.2%的效果好。供试菌株中celB4-5的有效性和竞争性最强,celB3-7次之,celB3-5差。