Biomass Yield,Nitrogen Accumulation and Nutritive Value of Mavuno Grass Inoculated with Plant Growth-promoting Bacteria

ABSTRACT

The objective of this study was to evaluate the effects of strains of Azospirillum brasilense, Pseudomonas fluorescens and Rhizobium tropici on the shoot dry weight (SDW) and root dry weight (RDW) yield, N uptake and nutritive value of ‘Mavuno’ grass inoculated with plant growth-promoting bacteria. We evaluated the effects of inoculation with the Ab-V5 and Ab-V6 strains of Azospirillum brasilense and Pseudomonas fluorescens or co-inoculation with Rhizobium tropici and Ab-V6, with and without nitrogen (N) application, as well as re-inoculations. The growth promoting bacteria + N promoted increases in SDW and RDW yield, tillers dry weight, relative chlorophyll index and N uptake. There were no effects of re-inoculation by Azospirillum brasilense, Pseudomonas fluorescens and Rhizobium tropici on nutrition, nutritive value and SDW and RDW yield, demonstrating that this technique still needs further studies with ‘Mavuno’ grass in the form and the correct period to be performed.     

Genotypic diversity and symbiotic effectiveness of rhizobia isolated from root nodules of Phaseolus vulgaris L. grown in Tunisian soils

 One hundred and sixty isolates of rhizobia were sampled from the root nodules of common bean (Phaseolus vulgaris L.) cultivated in Tunisian soil samples originating from three geographically distinct fields. Plasmid profiling was used as a primary method to rapidly screen the isolates, and then 38 plasmid types were recorded among the 160 isolates. A sample representing the majority of plasmid types was chosen for further characterization by restriction fragment length polymorphism (RFLP) analysis of genomic DNA using chromosomal and symbiotic gene probes, and by their ability to nodulate a potential alternative host, Leucaena leucocephala. One third of the isolates showed a high similarity to Rhizobium gallicum isolated from common bean in France, another third showed the same characteristics as the R. etli-R. leguminosarum group, while the remaining isolates could not be related to any of the five species nodulating bean. When reexamined for nodulation, some of these isolates, showing similarities to R. tropici and Agrobacterium with respect to colony morphology and growth in different media, failed to nodulate their original host. The R. gallicum-like isolates, R. etli-like isolates, and R. leguminosarum-like isolates were recovered from regions where bean is frequently grown, while in fields which had not been cultivated with beans for at least the 10 previous years, solely unrecognized taxa of ineffective isolates were recovered. We detected variations in the symbiotic regions, but certain pSym RFLP patterns for nifH were conserved between Tunisian, French, and Austrian populations of bean rhizobia. Evaluation of symbiotic effectiveness showed that R. gallicum-like isolates and R. etli-like isolates were effective, whereas some R. leguminosarum-like isolates were ineffective. Furthermore, effective isolates were also found among the unrecognized taxa. Received: 10 March 1998     

Interaction of biological nitrogen fixation with sowing nitrogen fertilization on common bean in the two seasons of cultivation in Brazil

Sowing nitrogen (N) fertilization can limit biological nitrogen fixation (BNF) reducing common bean yield. The aim of this study was to evaluate the effect of sowing N fertilization plus inoculation on the growth and yield of plants in the two seasons of cultivation in Brazil. In the dry season, N fertilization and inoculation promoted a greater shoot dry weight and higher pod number and yield than only inoculated. In contrast, in the rainy season, this treatment promoted no increase in shoot dry weight and yield compared with the inoculated alone. The number of nodules was greater for the inoculated alone treatment, but nodule weight was not affected by N fertilization in either season. Therefore, sowing N fertilization and inoculation can be an agronomic practice to achieve a higher common bean yield in the dry season, while in the rainy season, the inoculation without N fertilization can support a high yield at a lower cost.     

共生固氮在农牧业上的作用及影响因素研究进展

共生固N是生物固N的主体部分,具有固N效率高、应用范围广等特点。叙述了主要豆科作物年固N量及固N量占豆科作物本身所吸收N的比例,阐述了豆科作物在与非豆科作物间套轮作中固定N素的转移及对非豆科作物的影响,并介绍了影响豆科作物-根瘤菌共生体共生固N效率的主要因素。开展豆科作物-根瘤菌共生体系方面的研究对农业可持续发展具有重要意义。     

Effects of water and nitrogen availability on nitrogen contribution by the legume, Lupinus argenteus Pursh

Nitrogen-fixing species contribute to ecosystem nitrogen budgets, but background resource levels influence nodulation, fixation, and plant growth. We conducted a greenhouse experiment to examine the separate and interacting effects of water and N availability on biomass production, tissue N concentration, nodulation, nodule activity, and rhizodeposition of Lupinus argenteus (Pursh), a legume native to sagebrush steppe. Plants were grown in a replicated, randomized design with three levels of water and four levels of N. Additional water and N increased biomass except at the highest N level. All plants formed nodules regardless of treatment, but plants grown without N had the largest, most active nodules. Organic N was deposited into the rhizosphere of all plants, regardless of treatment, indicating that Lupinus can influence N availability while actively growing, even under water stress. High tissue N concentrations and low C:N ratios indicate that Lupinus also can provide substantial amounts of N through litter decomposition. The ability of Lupinus to affect N availability and cycling indicates that it has the potential to significantly influence N budgets and community composition within the sagebrush steppe.     

PHOSPHORUS USE EFFICIENCY FOR SYMBIOTIC NITROGEN FIXATION VARIES AMONG COMMON BEAN RECOMBINANT INBRED LINES UNDER P DEFICIENCY

This study compared the growth, nodulation, phosphorus use efficiency and nitrogen (N₂) fixation by six recombinant inbred lines (RILs) of Phaseolus vulgaris (RILs 147, 28, 83, 34, 7, and 104). These RILs were inoculated with Rhizobium tropici CIAT899 and grown in an aerated nitrogen-free nutrient solution at deficient versus sufficient phosphorous supplies (75 vs. 250 μmol P plant^?1 week^?1) in a glasshouse. Our results show that plant growth, nodulation, and symbiotic nitrogen fixation were significantly affected by P deficiency for all RILs, whereas this adverse effect was more pronounced in RILs 147, 83, 28 and 7 than in RILs 34 and 104. Under P deficiency, RILs 34 and 104 showed higher efficiency than other RILs in the use of P for their symbiotic N nutrition. It is concluded that P utilization efficiency may be a useful selection criterion for genotypic adaptation of N₂-fixing legumes to low P soils.     

白三叶草/根瘤菌共生固氮潜力及干旱限制因素

为了探讨白三叶草生物固氮与土壤水分供应和菌种基因型的关系,采用温室盆栽试验方法,对9个基因型的三叶草根瘤菌固氮效率和与土壤含水量的关系进行了研究。结果发现,根瘤菌接种后,白三叶草叶片含氮量明显增加,有3个基因型的根瘤菌接种植株后叶片氮含量达到对照的3倍以上,据此可根据根瘤菌的基因型来预测其固氮效率,共生固氮效率与根瘤菌基因型的关系较与分离宿主的关系更加密切。在中度干旱胁迫下,白三叶草植株地上部生物量积累所受影响较地下部所受影响更大,在白三叶草与根瘤菌共生体系建立过程中,当根瘤菌固定的氮素可以满足植株生长需要时,干旱胁迫可能成为生长的限制因子。     

Soil potassium effects on nitrogenase activity with associated nodule components of hairy vetch at anthesis

Acetylene reduction techniques are frequently utilized to estimate legume nodule nitrogenase activity levels. However, the known symbiotic nitrogen fixation reactions have no equivalent for the rapid permeastic transport of C₂H₄ reduced by nitrogenase of rhyzobial cells through the cortex tissues with the subsequent volatile excretion that is essential for GC quantitation procedures. The objective of this study was to determine interrelationships of nitrogenase (C₂H₂ reduction) with associated cytosol enzyme components from morphologically homologous nodules of Madison hairy vetch (Vicia villosa, Roth) at anthesis as influenced by soil potassium levels. The vetch plants were grown in a siliceous thermic Psammentic Paleustalf, Eufaula, and inoculated with Rhizobium leguminosarum Frank, ATCC 10314.

Highly significant enhancement of nitrogenase activity progressed from quadratic to linear with increased soil K levels in time‐course samplings at 30, 60, 90 and 120 min. incubations at 27C. Means as C₂H₄ μmole g^‐1 fresh nodule wt. were 25.1, 38.8, 50.1 and 92.2 for 0, 100, 200, and 300 mg K/kg soil, respectively.

Activity levels of four cytosol enzymes, aspartate aminotransferase (AST), glutamate dehydrogenase (GDH) glutamine synthetase (GS) and glutamate synthase (GOGAT), increased significantly with increased K soil levels. These are requisite to enzymatic pathways for fixed N ammonia biotransformations with subsequent xylem translocation from the legume nodule. The transaminase (AST) and ligase (GS) were dominant at all K levels with GS increasing linearly to six fold levels over the check treatment. Cytosol composition of total ureides and αKG increased significantly with increased soil K. levels. Cytosol Ca and Mg increases were not significant but highly significant increased K content with reciprocal decreased Na resulted from increased soil K levels. Multiple regression for the most reliable response surface equation within a general linear model with R² = 60.3% was: Nitrogenase (C₂H₂ reduction) = 2.84 nod. wt. + 1.05 GS + 8.08 αKG + 0.11 ureide, CV = 16.2%. Practical application of these data include need for more than single time‐course C₂H₄ determinations from one culture incubation in order to reliably estimate C₂H₂ reduction capabilities of legume nodules. Adequate levels of available soil potassium were necessary for sustained high nltrogenase activity levels.     

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。     

Nutrients Uptake in Shoots and Biomass Yields and Roots and Nutritive Value of Zuri Guinea Grass Inoculated with Plant Growth-promoting Bacteria

ABSTRACT

The objective of this study was to evaluate the effects of plant growth promoting bacteria (PGPB) inoculation in Zuri guinea grass [Megathyrsus (syn. Panicum) maximus] on shoot dry weight (SDW) and root dry weight (RDW) yield, morphological compositions, number of tillers, and nutrients concentrations in SDW. The experiment was carried out under greenhouse conditions in a randomized block design consisting of eight treatments with five replicates. The inoculation with the Ab-V5 and Ab-V6 strains of Azospirillum brasilense and Pseudomonas fluorescens or co-inoculation with Rhizobium tropici and Ab-V6, with nitrogen (N) fertilization, as well as re-inoculations of the plants after cuttings were taken were evaluated. The plant growth-promoting bacteria and N fertilization promoted increases in SDW and RDW yield, tillers dry weight, relative chlorophyll index (RCI) and nutrients uptake in shoots of Zuri guinea grass. There were effects of re-inoculation the PGPB by P. fluorescens in shoots, N, magnesium (Mg) and boron (B) concentration in SDW.     

短期低温对大豆苗期生长和结瘤固氮的影响

采用早熟大豆品种“黑河43”、晚熟大豆品种“东农53”进行盆栽试验,出苗后进行连续7d的低温处理（LT）,昼夜温度设定为13℃/3℃,以25℃/10℃为对照,从大豆出苗28d开始,每7d进行破坏性取样共4次,测定地上部和根干物质量、根瘤生物量、全氮含量及根瘤固氮量,研究苗期短期低温对大豆生长、结瘤和固氮能力的影响。结果表明：（1）大豆出苗后7d短期低温胁迫会延缓大豆生长发育。出苗后28～42d大豆生物量显著低于CK处理,出苗后49d低温胁迫对两个大豆品种生物量均无显著影响。（2）与CK相比,低温对“东农53”和“黑河43”根瘤形成的显著抑制作用分别出现在苗后42d和35d,根瘤数量分别降低了58.8%和72.0%。出苗后49d,低温使“东农53”和“黑河43”根瘤干重分别减少48.9%和48.5%。（3）低温刺激了两个品种大豆的生物固氮能力。在出苗后49d,低温处理“东农53”和“黑河43”的生物固氮量、单位根瘤生物量的固氮量和单个根瘤的固氮量分别增加了89.9%、118.9%,249.3%、172.6%,150.6%、114.2%。生物固氮百分率分别增加了26.4个和24.5个百分点。综合来看,大豆出苗后遭遇低温冷害会延缓生长发育,并抑制根瘤的形成与生长。低温胁迫解除后大豆生长逐步恢复。短期低温对大豆根瘤固氮量和根瘤固氮能力有刺激作用,对早熟品种“黑河43”刺激作用更明显。为了更好地适应东北大豆产区早春低温环境,推荐选用早熟品种大豆。     

Rhizobial inoculation improves drought tolerance,biomass and grain yields of common bean (Phaseolus vulgaris L.) and soybean (Glycine max L.) at Halaba and Boricha in Southern Ethiopia

ABSTRACT

While pulses are staple food-legumes in Ethiopia, their productivity is low due to low soil fertility. Elite rhizobial strains that significantly increased shoot dry weight and nitrogen (N) contents of common beans and soybeans in greenhouse were selected for two-year field trials to evaluate their effect on yields of the pulses in the field. Each pulse had six treatments, namely four rhizobial inoculants, uninoculated control, and synthetic N fertilizer. In the drought-affected year 2015, inoculated pulses tolerated moisture stress better than non-inoculated controls. Inoculation was conducive to higher or equivalent yields compared to synthetic N fertilizer. At Halaba, bean inoculated with strain HAMBI3562 gave the highest grain yield (1500 ± 81 kg ha^?1; mean±SE) while the control yielded only 653 ± 22 kg ha^?1. At Boricha, HAMBI3570 gave a grain yield (640 ± 35 kg ha^?1) comparable to synthetic N. When rainfall was optimal in 2016, inoculation with HAMBI3562 and HAMBI3570 gave grain yields (around 4300 kg ha^?1) equivalent to synthetic N. With soybean, strain HAMBI3513 produced consistently higher or comparable biomass and grain yields compared to synthetic N. In conclusion, HAMBI3562 and HAMBI3570 for beans and HAMBI3513 for soybeans can serve as inoculants for areas having similar conditions as the test areas.     

Influence of physical treatments on acetylene reduction (nitrogen fixation) in soils

Abstract

The effect of physical treatments such as drying, freezing, and heating on acetylene (C₂H₂) reduction (nitrogen fixation) in 3 types of soils was measured. Most treatments significantly affected ethylene (C₂H₄) production in the sandy loam. None of the treatments suppressed C₂H₄ formation in the sandy clay loam before 2 days. Muck soil with treatments of air‐drying, freeze‐drying, and freezing did not show different patterns in C₂H₄ production. However, auto claving and oven‐drying resulted in a pronounced increase in formation of C₂H₄. With exception of the heat treatments, no significant decreases in numbers of non‐symbiotic nitrogen‐fixers in soils were observed.     

新开垦土壤上构建玉米/蚕豆-根瘤菌高效固氮模式

为了在新开垦土壤上构建高效种植模式,本文采用温室盆栽和大田试验相结合的方法,选用4种根瘤菌接种方式(保水剂拌种、清水拌种、三叶期灌根和种子丸衣化)接种4种不同蚕豆根瘤菌(NM353、CCBAU、G254和QH258),分析接菌后新开垦土壤上玉米/蚕豆间作体系的生产潜力、地上部氮素吸收和结瘤特性以及生物固氮等方面的优势,拟为该体系筛选出高效的根瘤菌及其接种技术。结果表明:接种NM353后,玉米/蚕豆间作体系中蚕豆籽粒产量比单作平均增加152.84%,而玉米保持相对稳产;以保水剂拌种的方式接种NM353的间作蚕豆地上部氮素积累量最高,蚕豆结瘤数、瘤重、固氮比例和固氮量均高于本试验中其他3种方式接种的根瘤菌。在盛花期和盛花鼓粒期,接种NM353蚕豆的固氮比例比接种CCBAU的分别高19.1%和11.1%,在各个生育时期两者固氮量之间差异均达显著水平;接种NM353与接种其他菌种间固氮量和固氮比例差异更显著。因此,在新开垦土壤上,用保水剂拌种的方式对间作蚕豆接种NM353根瘤菌,构建玉米/蚕豆-根瘤菌高效固氮体系,为新开垦土壤合理开发利用的可持续发展模式。