Dry Weight and Nitrogen Content of Chickpea and Winter Wheat Grown in Pots for Three Rotations

ABSTRACT

Chickpea [Cicer arietinum (L.)] cultivars ‘ICCV-2’ and ‘Sarah’ were studied along with a control, multistrain, TAL 1148, and TAL 480 Bradyrhizobium strains to determine the effect(s) of cultivar and inoculum on dry weight (DW) and nitrogen (N) content of the legume, as well as soil mineral N, DW, and N content of wheat [Triticum aestivum (L.) emend. Thell.] in a continuous wheat-legume rotation. Chickpeas were planted during the summer and harvested in the fall of 1992, 1993, and 1994. Vegetative growth from chickpeas was incorporated into the soil prior to wheat planting, and soil cores were taken at 35 to 48 d after chickpea harvests. Additional summer fallow treatments for the winter wheat part of the experiment received 0, 45, and 90 kg N ha^?1 each year. Wheat plants were removed the following spring and stubble was incorporated into the soil before planting chickpeas in the summer. ‘Sarah’ chickpeas accumulated about the same or more shoot DW and shoot N compared to ‘ICCV-2’; whereas ‘ICCV-2’ generally produced more pod DW and pod N compared to ‘Sarah.’ Inoculum had no significant effect on chickpea DW or N content. Wheat DW and N following legumes increased marginally after growing ‘Sarah’ chickpeas, as evidenced by higher values of some treatments. Only the multistrain or absence of inoculum in ‘Sarah’ chickpeas resulted in significantly greater wheat DW or N content compared to the fallow wheat receiving no added N fertilizer. The contributions from ‘ICCV-2’ chickpeas to wheat DW and N content were not significant. Soil mineral N, as well as wheat DW and N content, fluctuated or increased during this three-year study, which demonstrated some benefit from incorporation of chickpeas into a wheat-legume cropping system.     

Effect of inoculum rate on the performance of chickpea (Cicer arietinum L.) Rhizobium strains in the field

Summary The influence of three inoculum rates on the performance of three chickpea (Cicer arietinum L.) Rhizobium strains was examined in the field on a Mollisol soil. Increasing amounts of inoculum improved the performance of the strains. A normal dose (10⁴ cells per seed) applied at different intervals gave non-significant increases in nodulation, nitrogenase activity (acetylene reduction assay), nitrogen uptake and grain yield. A ten-fold increase in inoculum increased nodule number, shoot dry weight, nitrogenase activity (ARA) and grain yield, but increases over the control were significant only for nodule dry weight and nitrogen uptake by shoot and grain. The highest level of inoculum (100 × normal) significantly increased nodule dry weight, grain yield, total nitrogenase activity (ARA) and nitrogen uptake by shoot and grain. Strain TAL 620 was more effective than the other two. Combined nitrogen (60 kg N ha^–1) suppressed nodulation and nitrogenase activity (ARA).Research paper No. 4345 from the Experiment Station, G. B. P. U. A. & T., Pantnagar, Nainital, U. P.     

The Symbiotic Performance and Plant Nutrient Uptake of Certain Nationally Registered Chickpea (Cicer Arietinum L.) Cultivars of Turkey

An experiment was conducted under greenhouse conditions to test the symbiotic performance and plant nutrient uptake of the twelve nationally registered chickpea cultivars (‘Çak?r’, ‘I??k-05’, ‘Can?tez-87’, ‘Hisar’, ‘Ya?a-05’, ‘Azkan’, ‘Küsmen-99’, ‘Gökçe’, ‘Damla-89’, ‘Diyar-95’, ‘Aziziye-94’, and ‘?zmir-92’) in Turkey. Inoculation with Mesorhizobium ciceri increased the average nodule number by 687%, nodule weight by 257%, plant height by 6%, shoot dry weight by 12%, root dry weight by 21%, chlorophyll content by 4.2%, nitogen (N)% by 7.9%, and total N by 22.7%. Averaged across chickpea cultivars, inoculation also significantly increased sulfur (S) by 14.4%, phosphorus (P) by 1.9%, magnesium (Mg) by 13.8%, potassium (K) by 6.2%, calcium (Ca) by 17.4%, copper (Cu) by 4.5%, iron (Fe) by 16.5%, manganese (Mn) by 10.9% and zinc (Zn) uptake by 9.4%. The macro- and micronutrient uptake of cultivars significantly correlated with their nitrogen content and the magnitude of response to inoculation in relation to nodulation, plant growth, nitrogen fixation, and nutrient uptake significantly varied among cultivars. Based on the amount of fixed N and plant nutrient uptake, ‘Azkan’, ‘Aziziye-94’, ‘Küsmen-99’, ‘Diyar-95’, and ‘Hisar’ were the genotypes with the most positive response to inoculation. Our data showed that nodulation, nitrogen fixation, plant dry matter production, and macro- and micronutrient uptake of the inoculated chickpea can be improved by selecting the best compatible cultivar.     

Effects of co-inoculation of Bradyrhizobium japonicum SAY3-7 and Streptomyces griseoflavus P4 on plant growth,nodulation, nitrogen fixation,nutrient uptake,and yield of soybean in a field condition

ABSTRACT

Co-inoculation of nitrogen-fixing bacteria with plant growth-promoting bacteria has become more popular than single inoculation of rhizobia or plant-growth-promoting bacteria because of the synergy of these bacteria in increasing soybean yield and nitrogen fixation. This study was conducted to investigate the effects of Bradyrhizobium japonicum SAY3-7 and Streptomyces griseoflavus P4 co-inoculation on plant growth, nodulation, nitrogen fixation, nutrient uptake, and seed yield of the ‘Yezin-6’ soybean cultivar. Nitrogen fixation was measured using the acetylene reduction assay and ureide methods. Uptake of major nutrients [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)] was also measured. This study showed that single inoculation of SAY3-7 significantly increased shoot biomass; nodulation; Relative Ureide Index (RUI %), percent nitrogen derived from N fixation (% Ndfa); N, P, K, Ca, and Mg uptakes; during the later growth stages (R3.5 and R5.5), compared with control. These observations indicate that SAY3-7 is an effective N-fixing bacterium for the plant growth, nodulation, and nitrogen fixation with an ability to compete with native bradyrhizobia. Co-inoculation of SAY3-7 and P4 significantly improved nodule number; nodule dry weight; shoot and root biomass; N fixation; N, P, K, Ca, and Mg uptake; at various growth stages and seed yield in ‘Yezin-6’ soybean cultivar compared with the control, but not the single inoculation treatments. Significant differences in plant growth, nodulation, N fixation, nutrient uptake, and yield between co-inoculation and control, not between single inoculation and control, suggest that there is a synergetic effect due to co-inoculation of SAY3-7 and P4. Therefore, we conclude that Myanmar Bradyrhizobium strain SAY3-7 and P4 will be useful as effective inoculants in biofertilizer production in the future.     

Comparative efficieny of Rhizobium/Bradyrhizobium spp. strains in nodulating Cajanus cajan in relation to characteristic metabolic enzyme activities

The comparative symbiotic properties of Rhizobium spp. and Bradyrhizobium spp. strains infecting pigeon pea were evaluated. Bradyrhizobium strains (Cajanus) were found to be superior to Rhizobium strains (Cajanus) and the superiority was ascertained to be due to the higher enzyme activity of the tricarboxylic acid (TCA) cycle in comparison to Rhizobium spp. strains. Moreover, metabolic superiority or rapid growth rate does not necessarily correlate with symbiotic effectiveness. The symbiotic performance of isolates varied with the host cultivar. The dry matter accumulation could be correlated with the total acetylene reduction activities rather than nodule number or nodule fresh weight per plant. Received: 3 March 1993     

Potential for enhancement of root growth and nodulation of soybean co-inoculated with Azospirillum and Bradyrhizobium in laboratory systems

The potential enhancement of root growth and nodulation in vegetable soybean (AGS190) was studied with application of Azospirillum brasilense (Sp7) and A. lipoferum (CCM3863) co-inoculated with two Bradyrhizobium japonicum strains (TAL102 and UPMR48). Significant root growth stimulation and nodulation were observed in Azospirillum as well as during its co-inoculation with Bradyrhizobium. Nodule formation is linked with the initiation of new roots; nodules were almost absent even in Bradyrhizobium inoculated plant due to the absence of new roots development in clipped rooted seedlings. Total root length, root number, specific root length, root dry matter, root hair development and shoot dry matter were significantly increased by Azospirillum alone and its co-inoculum. Co-inoculated plants significantly influenced the number of nodules and its fresh weight. A. brasilense seemed to perform better in root growth and nodule development compared to A. lipoferum.     

Nodulation and nitrogen fixation of Lupinus species with Bradyrhizobium (lupin) strains in iron-deficient soil

 The effect of six Bradyrhizobium sp. (lupin) strains (WPBS 3201D, WPBS 3211D, USDA 3040, USDA 3041, USDA 3042 and CB 2272) and Fe supply on nodulation, N₂-fixation and growth of three lupin species (Lupinus termis, L. albus and L. triticale) grown under Fe deficiency in an alkaline soil, were examined in sterilized and non-sterilized pot experiments. When inoculated with USDA 3040, 3041, 3042 and CB2272 without Fe addition, the three lupin species had a very low nodule number and mass, low shoot and root dry matter accumulation and lower N yield. However, inoculation with WPBS 3201D and 3211D without Fe treatments increased all these parameters substantially. The ability of WPBS 3201D and 3211D to form nodules on the three lupin species under conditions of Fe stress could be attributed to their ability to scavenge Fe from Fe-deficient environments through their siderophore production. Addition of Fe to the other four strains significantly increased nodulation and N₂-fixation of the three lupin species, indicating that the poorer nodulation and N₂-fixation of these strains in the absence of Fe, resulted from a low ability to obtain Fe from alkaline soils. Bradyrhizobium strains WPBS 3201D and 3211D were superior to the other four strains in terms of promoting greater nodulation, N₂-fixation, plant growth and N accumulation of L. termis and L. albus. However, the other four strains were more efficient in symbiotic association with L. triticale. The greater variations in nodule efficiencies (specific nitrogenase activity) under different levels of Fe supply could be attributed to the quantities of bacteroid protein and leghaemoglobin in the nodules. The results suggested that Bradyrhizobium (lupin) strains differ greatly in their ability to obtain Fe from alkaline soils, and that the selection of bradyrhizobial strains which are tolerant of Fe deficient soils could complement plant breeding for the selection of legume crops for Fe-deficient soils. Received: 5 January 1998     

Nitrogenase divarication with histological attributes distinctive for glycosylated aerial stem nodules and nitrosylated root nodules of sesbania

Exceptional symbiotic nitrogen fixation with Sesbania has provided high soil fertility for many past centuries of paddy rice production. Unique stem nodulation results in high nitrogenase activity levels of S. rostrata, Brem, during rapid growth in continuously flooded rice fields that greatly disfavor legume root nodulation and this functional development. The objective of this study was to determine plant nutrient interactions that influence contrasting root and aerial stem nodule histology governing effective nitrogenase activity levels and nitrogen fixation. Top growth, nodulation, and nitrogenase activity levels were significantly increased with increased available soil P. Response to K levels and Ca additions resulted only when soil P was adequate in all treatment combinations. However, there was no significant correlation between fresh nodule weight, nitrogenase activity, and nodules plant^‐1 for both root nodules and aerial stem nodules. Nodule histology was highly contrastive with nodule type and Rhizobium morphology, cytosol composition, and governing enzyme activity levels. Distinctive nonpleomorphic cocci bacteroids of functional aerial stem nodules have tentative designation as Azorhizobium caulinodans gen. nov. sp. nov.     

The diversity of rhizobia nodulating chickpea (Cicer arietinum) under water deficiency as a source of more efficient inoculants

Chickpea is an important pulse crop grown mainly in the arid and semi-arid regions. The effect of water deficiency on nodulation, biomass production, and competition for nodule occupancy was evaluated in three different soils with two chickpea cultivars, Amdoun I and Chetoui. Two watering regimes were considered; a control that was irrigated three times per week and a water-deficient treatment that was irrigated only one time a week. Results showed that water deficiency significantly decreased the nodule number and the shoot dry weight for both cultivars. Root-nodule bacteria were isolated and characterized by PCR-RFLP of 16S rDNA and nifD-K intergenic spacer. The results show that water deficiency affects the diversity of nodulating rhizobia. The nodulation by Mesorhizobium mediterraneum was reduced while inefficient nodulation by Ensifer meliloti was favoured. In both treatments, chickpea was preferentially nodulated by nifD-K type N6. Analysis for NaCl tolerance showed that most of rhizobia nodulating chickpea under water deficiency are NaCl tolerant. Inoculation with the selected salt-tolerant strain of M. mediterraneum LILM10 increased significantly nodule number and grain yield in the field.     

Enhancement of Nodulation and Yield of Chickpea by Co-inoculation of Indigenous Mesorhizobium spp. and Plant Growth–Promoting Rhizobacteria in Eastern Uttar Pradesh

We study the effect of plant growth–promoting rhizobacteria (PGPR) along with Mesorhizobium sp. BHURC02 on nodulation, plant growth, yield, and nutrient content of chickpea (Cicer arietinum L.) under field conditions. A similar study has been conducted for nodulation and plant growth of chickpea in pot experiment under glasshouse conditions. The treatment combination of Mesorhizobium sp. BHURC02 and Pseudomonas fluorescens BHUPSB06 statistically significantly increased nodule number plant^–1, dry weight of nodule plant^–1, and root and shoot dry weights plant^–1 over the control under a glasshouse experiment. The maximum significant increase in nodule number, dry matter, and nutrient content were recorded in co-inoculation of Mesorhizobium sp. BHURC02 and P. fluorescens BHUPSB06 followed by co-inoculation of Mesorhizobium sp., Azotobacter chroococcum, and Bacillus megatrium BHUPSB14 over uninoculated control in a 2-year field study. Hence, co-inoculation of Mesorhizobium sp. and P. fluorescens may be effective indigenous PGPR for chickpea production.     

<Emphasis Type="Italic">Rhizobium</Emphasis>,<Emphasis Type="Italic"> Bradyrhizobium</Emphasis> and<Emphasis Type="Italic"> Agrobacterium</Emphasis> strains isolated from cultivated legumes

The present study was conducted to isolate and characterize rhizobial strains from root nodules of cultivated legumes, i.e. chickpea, mungbean, pea and siratro. Preliminary characterization of these isolates was done on the basis of plant infectivity test, acetylene reduction assay, C-source utilization, phosphate solubilization, phytohormones and polysaccharide production. The plant infectivity test and acetylene reduction assay showed effective root nodule formation by all the isolates on their respective hosts, except for chickpea isolate Ca-18 that failed to infect its original host. All strains showed homology to a typical Rhizobium strain on the basis of growth pattern, C-source utilization and polysaccharide production. The strain Ca-18 was characterized by its phosphate solubilization and indole acetic acid (IAA) production. The genetic relationship of the six rhizobial strains was carried out by random amplified polymorphic DNA (RAPD) including a reference strain of Bradyrhizobium japonicum TAL-102. Analysis conducted with 60 primers discriminated between the strains of Rhizobium and Bradyrhizobium in two different clusters. One of the primers, OPB-5, yielded a unique RAPD pattern for the six strains and well discriminated the non-nodulating chickpea isolate Ca-18 from all the other nodulating rhizobial strains. Isolate Ca-18 showed the least homology of 15% and 18% with Rhizobium and Bradyrhizobium, respectively, and was probably not a (Brady)rhizobium strain. Partial 16S rRNA gene sequence analysis for MN-S, TAL-102 and Ca-18 strains showed 97% homology between MN-S and TAL-102 strains, supporting the view that they were strains of B. japonicum species. The non-infective isolate Ca-18 was 67% different from the other two strains and probably was an Agrobacterium strain.     

Effect of the expression of Escherichia coli fhuA gene in Rhizobium sp. IC3123 and ST1 in planta: Its role in increased nodule occupancy and function in pigeon pea

The inability to utilize a fungal siderophore as source of iron nutrition by most of the rhizobial cultures isolated from pigeon pea, could be considered a negative fitness factor since hydroxamate siderophores are found in significant amounts in natural soils. Thus these cultures were engineered to use ferrichrome a prototype of hydroxamate type siderophore. Pigeon pea Rhizobium spp. IC3123 and ST1 harboring Escherichia coli fhuA gene, responsible for uptake of Fe³⁺-ferrichrome, were obtained by transformation with pGR1, a broad host range plasmid carrying the fhuA gene under the control of the lac promoter of E. coli. Expression of fhuA in transformed rhizobial strains IC3123::pGR1 and ST1::pGR1 was confirmed by the ability of the plasmid-bearing strains to utilize iron bound to ferrichrome. Inoculation of pigeon pea plants with fhuA expressing rhizobial strains in pot experiments showed a significant increase in plant growth as well as nodule density as compared to those inoculated with the parent as well as the empty vector-bearing strain. Inoculation of pigeon pea seedlings with IC3123::pGR1 and ST1::pGR1 led to marked increase in shoot fresh weight, nodule number per plant, chlorophyll content of leaves and effective nodule symbiosis when compared with plants inoculated with the parent strains IC3123 and ST1. The positive effect of IC3123::pGR1 and ST1::pGR1 treatment on plant growth was more significantly observed when ferrichrome producing Ustilago maydis, known to secrete ferrichrome, was co-inoculated along with the transformed rhizobia. The presence of fhuA gene in rhizobial strains also led to an increased survival and root colonization.     

Soil fertility effects on growth,yield, nodulation and nitrogenase activity of Austrian winter pea

Austrian winter pea (Pisum sativum subspecies arvense (L.) Poir) is grown as a cool season annual to produce high protein seed and forage as well as for soil fertility improvement. This legume is grown on a wide range of soil types with many different cropping systems. The objective of these studies was to determine the influence of K levels, with and without P and Ca fertilization, for increased growth, yield, nodulation and nitrogenase activity. Results were from 3 years’ field and greenhouse experiments with a Psammentic Paleustalf (Eufaula series) utilizing Rhizobium leguminosarum (Frank), ATCC 10314 as inoculum. Soil fertility effects on composition and histology of field‐grown nodules are presented.

Available soil P was a limiting plant nutrient in field studies with significant response to K resulting with PK combinations for top growth, tillers, pods, seed yield, nodule mass, and nitrogenase activity levels (C₂H₂, red.). Multiple regression for nitrogenase (umol C₂H₄ h^‐1) = 1.09 tiller number + 3.37 nodule weight + 2.29 pod number, R² = 0.837, C.V. = 29.9%. Results from the greenhouse experiments indicated significant responses with increased K application levels when combined with P and Ca fertilization for top growth, nodule weight, number of nodules and nitro‐genase activity. Highly significant correlations resulted with nitrogenase x nodule weight (r=0.538) and nitrogenase x top growth (r=0.359) with multiple regression of treatment effects for nitrogenase (μmol C₂H₄ h^‐1) = 2.73 P + 1.04 K + 4.92 Ca, R² = 0.797 and C.V. = 48.8%. Soil addition of plant nutrients resulted in significantly increased concentrations of those elements within nodules. Magnesium content was not consistently influenced by P, Ca, and K amendments. Sodium decreased with increased K fertilization. Multiple regression of elemental composition (mg g^‐1 nodule) for nitrogenase (pmol C₂H₄ h^‐1) = 0.21 P + 0.86 K + 2.35 Ca ‐ 2.01 Na, R² = 0.772, C.V. = 55.6%. The proportion of plant nutrients in nodules contained within the nodule cytosol was highest for K (56.2%) and lowest for Ca (21.4%) with intermediate levels of Mg (50.2%), P (45.4%), and Na (37.2%).

Practical application from these data include the requirement of adequate available soil K for increased yield and nitrogen fixation with favorable P and Ca soil levels in Austrian winter pea production.     

Limitations of colony morphology and antibiotic resistance in the identification of a Bradyrhizobium sp. (Lotus) strain in soil

Summary We investigated the reliability of antibiotic resistance and colony morphology of clones of a Bradyrhizobium sp. (Lotus) strain for strain identification in nodulation competitiveness experiments in soil. There was no difference in nodulation competitiveness between the wild type strain and each of five mutants resistant to streptomycin and spectinomycin at the time of their isolation from antibiotic-containing media. However, these mutants were significantly less competitive when tested 4 months later. The apparent instability of the newly isolated mutants and their subsequently decreased nodulation competitiveness show that mutants must be examined carefully after being allowed time to stabilize. Two clones of the Bradyrhizobium sp. (Lotus) strain that differed in colony morphology on yeast mannitol medium did not differ in antigenic properties, whole cell protein electrophoresis profiles, mean cell generation times in yeast mannitol medium, N₂-fixing ability, nodulation of Lotus pedunculatus in growth pouches, or in nodulation competitiveness. Both clones retained their colony morphology after numerous transfers on yeast mannitol agar over 3 years and after at least 6 months in soil. A limiting factor, which may restrict the use of colony morphology as a marker for strain identification in competition experiments, is the problem of detecting double-infected nodules when the small colony type comprises a relatively small portion of the total nodule population.     

Mycorrhiza and soil fertility effects with growth,nodulation and nitrogen fixation of leucaena grown on a typic eutrustox

Abstract

The rapidly growing, woody perennial legume, Leucaena (Leucaena leucocephala (Lam.) de Wit), is adaptable to a wide range of neotropical soil conditions. Effective Rhizobium inoculation and endophyte mycorrhizal colonization are essential for high levels of production and symbiotic N₂ fixation. The objective of this study was to determine growth, nodulation, nitrogenase activity and nodule composition of inoculated Leucaena as affected by mycorrhizal colonization and factorial soil fertility treatments of a Typic Eutrustox. Highly significant increases in top growth, nodule fresh wt. and nitrogenase activity resulted with Glomus fasciculatum colonization, soil K and linear increases with low‐soluble P fertilization to 300 mg P kg^‐1 soil. Highly significant interactions for increased nodulation and nitrogenase activity resulted with K × mycorrhiza. Interactions of all three factors P, K and mycorrhiza were highly significant for nodule fresh wt. However, responses comparing inoculation with G. fasciculatum and with combined G. fasciculatum, G. microcarpus and G. clavium were not significant. Highly significant increases with applied K levels to 300 mg K kg^‐1 soil resulted with top and root growth, nodulation and nitrogenase when applied with soluble P at 100 mg kg^‐1 soil and 500 mg Ca kg^‐1 soil. Significant and highly significant interactions of P, Ca and K level resulted for all parameters. Plant nutrient element composition of nodules increased with the fertilization treatments for P, Ca and increased K levels. A highly significant inverse relation was apparent with decreased Na resulting with increased K levels. Half or more of total nodule K, P and Mg but less than 20% of Ca and Na were within the nodule cytosol. Sodium, Mg, P, and Ca decreased in the cytosol fraction with increased K content.     

Variation in symbiotic characters of alfalfa cultivars inoculated with Sinorhizobium meliloti strains

In this paper the interactive effects of different Sinorhizobium meliloti strains and alfalfa cultivars on the host plant growth and nodulation were evaluated. In the experiments, six alfalfa cultivars (Giza-1, Ismailia-94, Kometa, Radius, Luzella and Legend) as well as five S. meliloti strains (ARC-1, ARC-2, A₂, TAL and L5-30) were included. The alfalfa cultivars, Giza-1 and Ismailia-94, exhibited the highest average dry forage weight with all studied strains. Generally, plants inoculated with the S. meliliti ARC-2 strain produced significantly higher shoot and root dry weights over all evaluated cultivars. The strain L5-30 of S. meliloti produced the highest nodule number with all the studied alfalfa cultivars whereas, among tested cultivars, N₂-fixing Luzella showed the highest nodulation with the majority of rhizobial strains. Analysis of correlation coefficients for the studied alfalfa-rhizobium associations revealed positive and significant relationships of shoot dry weight with root dry weight. In contrast, nodule number per plant correlated negatively with forage dry weight of plants. It was also found that nodule number per plant is not a promising trait with which to select the most effective N₂-fixing rhizobium-legume systems; selection of such symbiotic associations should be done on the basis of shoot and root dry weights.     

Soil fertility effects on nodulation,nitrogen fixation,and yields of guar, (Cyamopsis tetragonoloba (L.) Taub.), grown on a typic eutrustox

Guar (Cyamopsis tetragonoloba (L.) Taub.) is a legume of unusual industrial importance due to increased utilization of Guar gum, ‘Guran,’ in numerous modern manufacturing and food processes. Guar has high tolerance of drought and inhibitory soil characteristics and has been utilized for many centuries within the subhumid regions of the Indo‐Pakistan subcontinent. Nodulation, nitrogen fixation, and yields of high protein seed with desirable Guran content are improved by favorable soil fertility. Plant growth, seed yields, and nodulation are influenced by plant population density.

Top Growth quadratically increased with plant population densities of 10, 25, and 50 plants per meter² for P and P+K treatments. Highest seed yield and nodule development resulted for all soil fertility treatments with 25 plant per meter². Ontogenetic response from anthesis to full seed maturity resulted with increased nodulation significantly correlated (r = 0.67) with top growth. However, nitrogenase activity levels plant‘¹ declined significantly with plant maturity. Nodule cytosol enzyme activity levels at anthesis were: allantoinase (ALTN) 29.5 IU, aspartate transaminase (AST) 19.3 IU, glutamine synthase 12.5 IU, uricase (URC) 2.25 IU, and allantoicase (ALTC) 0.14 IU g^‐1 fresh nodule. Cytosol composition included ureidoglycolates (ureides) 425.8 μmol, amine‐amide content 29.5 μmol, nitrate 1.95 μmol, pyruvate 0.21 μimol, and oketoglutarate 0.09 μmol g‘¹ fresh nodule. Plant nutrient composition of nodule cytosol was K 394.9 jig, P 59.4 μg, Ca 48.9 μg, Mg 39. μg, and Na 19.0 μg g^‐1 fresh nodule. Precise histology with Giemsa and PAS procedures were essential for microscopy with cellular compartmentalization of purine enzymatic transformations governing nitrogenase activity and nodule development.     

氮肥对大豆结瘤固氮、籽粒产量和蛋白质含量的影响

【目的】合理施用氮肥不仅可提高大豆结瘤固氮能力,还可减少农业污染,实现大豆生产的高产优质高效。研究施氮时期和施氮量对大豆结瘤固氮、产量及蛋白质含量的影响,为大豆高产优质提供理论基础及科学依据。【方法】采用盆栽试验,供试大豆品种为‘东生35’,试验设2个氮肥施用时期(V2期和R1期)和3个氮肥施用量[N 0、5、100 mg/(kg,土)],表示为N0、N5和N100。在大豆R2期(盛花期)和R5期(鼓粒期)取样分析了地上部干物质积累量、根瘤数量、根瘤干重和固氮酶活性。在R8期(成熟期)调查了大豆籽粒产量和蛋白质含量。【结果】施氮时期和施氮量对大豆地上干物质积累、结瘤和固氮能力均有显著影响。不论是V2期还是R1期施氮,大豆地上部干物质积累量均随着施氮量的增加而增加,而根瘤干重、数量则呈降低的趋势。R1期施氮条件下,N100处理的大豆盛花期根瘤数量和根瘤干重比N0分别下降了42.3%和32.8%,而固氮酶活性则均以N5处理最高;V2期施氮条件下,N5处理的大豆固氮酶活性在R2期和R5期较N0处理分别增加15.3%和27.1%。大豆籽粒产量和蛋白质含量均以N5处理最高,籽粒蛋白质含量较N0处...     

Exceptional forage regrowth,nodulation and nitrogenase activity of kudzu (Pueraria lobata (Willd.) Ohivi) grown on eroded Dougherty loam subsoil

Kudzu (Pueraria lobata (Willd.) Ohivi) is a hardy, perennial deciduous legume and a high protein, preferred forage for all livestock and poultry. However, when underutilized for pasturage, Kudzu's unrestricted, robust climbing vine development is impressive to highway travelers throughout the southeastern United States. Kudzu was effectively utilized for erosion control and soil improvement following introduction to the U.S. from Japan in 1876. Unique characteristics include distinctive nodulation with high nitrogenase activity levels, rapid regrowth of pastured foliage, profuse xylem transport of ureide components adjunctive to nitrogen fixation, and the very useful characteristic of vigorous, productive adaptiveness to eroded, low fertility soils. The objective of this study was to determine plant nutrient interactions influencing Kudzu regrowth, nodulation, nodule histology, and xylem exudate components. Available soil phosphorus within eroded, Dougherty loam subsoil was the limiting plant nutrient for Kudzu growth, nodulation and nitrogenase activity. Significant increases with K and Ca only resulted when combined with P fertilization. Distinctive nodule morphology includes prominent mesothelial sclerenchyma closely associated with high levels of ureide synthates. Vigorous regrowth, nodulation and nitrogenase activity levels of Kudzu occurred with 30 day interval clipping. Profuse xylem exudate of clipped stems provided quantitative determinations of nodule ureide transformation and transport components. Governing enzyme associations for glyoxylate transition were determined with improved, precise histology and specific cytological compartmentative polystain techniques.     

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.