Increase In Nodulation Research Articles

Maize/Peanut Intercropping Affects Legume Nodulation in Semi-Arid Conditions

Maize/peanut intercropping is practiced widely to increase land productivity and considered a sustainable way for using and saving resources through peanut’s complementary N source via biological N2 fixation. Our study aims to understand how maize/peanut intercropping affects the nodulation of peanuts under water-limiting conditions and different nitrogen inputs. A two-year micro-plot experiment in 2015–2016 and a two-year field experiment in 2017–2018 were conducted to quantify nodulation in maize/peanut intercropping and sole peanut cropping under four N fertilization rates (N-free, low, medium, and high N) in rain-fed water-limited conditions. In the micro-plot experiment, intercropped peanuts increased nodule biomass compared to sole peanuts. The nodule number of intercropped peanuts was 51.6% (p = 0.001) higher than that of sole cropped peanuts, while nodule weights did not differ at high N fertilization rates and were lower in the no-N fertilization control. However, the results were different in the field experiment. Both the nodule number and single weight of the sole cropped peanut were 48.7% (p = 0.020) and 58.9% (p = 0.014) higher than that of the intercropped peanut. The ratio of the nodule weight to aboveground dry matter at the beginning peg in the dry year of 2017 was lower in intercropping than sole cropping, especially at low N fertilization rates. The potential increase in nodulation found in a well-controlled micro-plot environment might be limited by strong water and light competitions in field conditions. The results could contribute to the understanding of interspecific interactions in cereal/legume intercropping.

Purification and Characterization of Desferrioxamine B of Pseudomonas fluorescens and Its Application to Improve Oil Content, Nutrient Uptake, and Plant Growth in Peanuts

Microorganisms produce siderophores, which are low-molecular-weight iron chelators when iron availability is limited. The present analyzed the role of LNPF1 as multifarious PGPR for improving growth parameters and nutrient content in peanut and soil nutrients. Such multifarious PGPR strains can be used as effective bioinoculants for peanut farming. In this work, rhizosphere bacteria from Zea mays and Arachis hypogaea plants in the Salem area of Tamil Nadu, India, were isolated and tested for biochemical attributes and characteristics that stimulate plant growth, such as the production of hydrogen cyanide, ammonia (6 µg/mL), indole acetic acid (76.35 µg/mL), and solubilizing phosphate (520 µg/mL). The 16S rRNA gene sequences identified the isolate LNPF1 as Pseudomonas fluorescens with a similarity percentage of 99% with Pseudomonas sp. Isolate LNPF1 was evaluated for the production of siderophore. Siderophore-rich supernatant using a Sep Pack C18 column and Amberlite-400 Resin Column (λmax 264) produced 298 mg/L and 50 mg/L of siderophore, respectively. The characterization of purified siderophore by TLC, HPLC, FTIR, and 2D-NMR analysis identified the compound as desferrioxamine, a hydroxamate siderophore. A pot culture experiment determined the potential of LNPF1 to improve iron and oil content and photosynthetic pigments in Arachis hypogaea L. and improve soil nutrient content. Inoculation of A. hypogea seeds with LNPF1 improved plant growth parameters such as leaf length (60%), shoot length (22%), root length (54.68%), fresh weight (47.28%), dry weight (37%), and number of nuts (66.66) compared to the control (untreated seeds). This inoculation also improved leaf iron content (43.42), short iron content (38.38%), seed iron (46.72%), seed oil (31.68%), carotenoid (64.40%), and total chlorophyll content (98.%) compared to control (untreated seeds). Bacterized seeds showed a substantial increase in nodulation (61.65%) and weight of individual nodules (95.97) vis-à-vis control. The results of the present study indicated that P. fluorescens might be utilized as a potential bioinoculant to improve growth, iron content, oil content, number of nuts and nodules of Arachishypogaea L., and enrich soil nutrients.

Soybean Response to Seed Inoculation or Coating with Bradyrhizobium japonicum and Foliar Fertilization with Molybdenum.

Soybean is one of the most important legumes in the world, and its advantages and disadvantages are well known. As a result of symbiosis with the bacterium Bradyrhizobium japonicum, soybean can assimilate nitrogen from the air and is therefore not fertilized with this element, or if it is, only at small doses. In soybean agriculture practice, an important treatment is the inoculation of seeds with symbiotic bacteria and optimal fertilization with selected nutrients. Therefore, a three-year (2019-2021) field experiment was carried out to investigate the effects of soybean in the field to a seed Rhizobium inoculation or coating and molybdenum foliar fertilization. There were no significant interactions between the tested treatments over the years. It was demonstrated that the best variant was seed inoculation before sowing in combination with foliar molybdenum application. As a result of this treatment, a significant increase in nodulation, soil plant analysis development (SPAD) index, leaf area index (LAI) and seed yield (by 0.61 t·ha-1) was obtained compared to the control. In addition, the content of total protein in the seeds increased, while the content of crude fat decreased, which significantly modified the yield of both components. Sowing coated seeds in the Fix Fertig technology was less effective compared to inoculation, but it was significantly better than that in the control. Coating seeds with B. japonicum, in combination with foliar fertilization with molybdenum, could be recommended for agricultural practice, which was confirmed by economic calculations. Future experiments will assess the soybean's response to seed inoculation or coating and fertilization with other micronutrients.

Hydroponic Common-Bean Performance under Reduced N-Supply Level and Rhizobia Application.

This study aims to explore the possibility of a reduced application of inorganic nitrogen (N) fertiliser on the yield, yield qualities, and biological nitrogen fixation (BNF) of the hydroponic common bean (Phaseolus vulgaris L.), without compromising plant performance, by utilizing the inherent ability of this plant to symbiotically fix N2. Until the flowering stage, plants were supplied with a nutrient solution containing N-concentrations of either a, 100%, conventional standard-practice, 13.8 mM; b, 75% of the standard, 10.35 mM; or c, 50% of the standard, 6.9 mM. During the subsequent reproductive stage, inorganic-N treatments b and c were decreased to 25% of the standard, and the standard (100% level) N-application was not altered. The three different inorganic-N supply treatments were combined with two different rhizobia strains, and a control (no-inoculation) treatment, in a two-factorial experiment. The rhizobia strains applied were either the indigenous strain Rhizobium sophoriradicis PVTN21 or the commercially supplied Rhizobium tropici CIAT 899. Results showed that the 50-25% mineral-N application regime led to significant increases in nodulation, BNF, and fresh-pod yield, compared to the other treatment, with a reduced inorganic-N supply. On the other hand, the 75-25% mineral-N regime applied during the vegetative stage restricted nodulation and BNF, thus incurring significant yield losses. Both rhizobia strains stimulated nodulation and BNF. However, the BNF capacity they facilitated was suppressed as the inorganic-N input increased. In addition, strain PVTN21 was superior to CIAT 899-as 50-25% N-treated plants inoculated with the former showed a yield loss of 11%, compared to the 100%-N-treated plants. In conclusion, N-use efficiency optimises BNF, reduces mineral-N-input dependency, and therefore may reduce any consequential negative environmental consequences of mineral-N over-application.

Novel approach to enhance Bradyrhizobium diazoefficiens nodulation through continuous induction of ROS by manganese ferrite nanomaterials in soybean

BackgroundThe study of symbiotic nitrogen fixation between (SNF) legumes and rhizobia has always been a hot frontier in scientific research. Nanotechnology provides a new strategy for biological nitrogen fixation research. However, how to construct abiotic nano-structure-biological system, using the special properties of nanomaterials, to realize the self-enhancement of biological nitrogen fixation capacity is important.ResultsIn order to construct a more efficient SNF system, in this study, we applied manganese ferrite nanoparticles (MF-NPs) with sustainable diatomic catalysis to produce reactive oxygen species (ROS), thus regulating the nodulation pathway and increasing the number of nodules in soybean (Glycine max), eventually enhancing symbiotic nitrogen fixation. Symbiosis cultivation of MF-NPs and soybean plants resulted in 50.85% and 61.4% increase in nodule weight and number, respectively, thus inducing a 151.36% nitrogen fixation efficiency increase, finally leading to a 25.70% biomass accumulation increase despite no substantial effect on the nitrogenase activity per unit. Transcriptome sequencing analysis showed that of 36 differentially expressed genes (DEGs), 31 DEGs related to soybean nodulation were upregulated in late rhizobium inoculation stage (12 d), indicating that the increase of nodules was derived from nodule-related genes (Nod-R) continuous inductions by MF-NPs.ConclusionsOur results indicated that the nodule number could be effectively increased by extending the nodulation period without threatening the vegetative growth of plants or triggering the autoregulation of nodulation (AON) pathway. This study provides an effective strategy for induction of super-conventional nodulation.Graphical

Bradyrhizobium strains from Brazilian tropical soils promote increases in nodulation, growth and nitrogen fixation in mung bean

Mung bean [Vigna radiata (L.) Wilczek] is a legume of Asian origin cultivated in several countries, including Brazil, where its commercial cultivation has expanded in recent years. It has a promiscuous N2-fixing association with rhizobia, but nodulation in Brazilian soils has been highly variable. To achieve satisfactory yields with low production costs, studies are being carried out to select rhizobia from soils in Brazil that result in efficient symbiotic associations with mung bean. Previous studies indicate that only Bradyrhizobium strains were able to nodulate mung bean in Brazilian soils. The objective of this study was to evaluate the effect of 31 Bradyrhizobium strains and increasing levels of N fertilizer on nodulation, plant growth and N2 fixation. Bradyrhizobium strains resulted in increases of up to 71, 79, 43, 66, 40 and 55%, respectively, in nodule number and nodule, root and shoot biomasses, accumulated N and biological nitrogen fixation (BNF) contribution compared to the uninoculated control, however, there was no increase in grain yield. Compared to the control with N fertilizer, inoculated plants had lower biomass and accumulated N, despite the high BNF contribution. In general, strains of Bradyrhizobium japonicum superclade, especially those close to B. yuanmingense B071, showed greater efficiency compared to those of the superclade of B. elkanii. The application of N fertilizer increased root and shoot biomasses, however, significantly reduced nodulation. Bradyrhizobium strains isolated from Brazilian tropical soils showed potential for mung bean inoculation, however, the BNF contribution was not sufficient to meet the plant's N demand.

Seeking Alfalfa Resistance to a Rhizophagous Pest, the Clover Root Curculio (Sitona hispidulus F.).

Simple SummaryClover root curculio (CRC) is a root feeding pest of alfalfa and clover that reduces stand life and yield. With the cancellation of soil-active insecticides in alfalfa, CRC populations and associated root damage have increased. Current CRC management practices are limited in their ability to suppress larval feeding belowground. Here, we evaluated alfalfa populations for resistance to CRC larval feeding and development belowground, and adult leaf consumption and oviposition aboveground. Divergent selection in two alfalfa cultivars in field nurseries revealed that there is genetic variability in resistance to CRC larval feeding and that significant gains in resistance from selection can occur in as few as two or three cycles of selection. While larval development was similar across the alfalfa populations tested in the lab, one alfalfa population (NY1713) displayed an overall increase in nodulation resulting in significantly lower proportions of nodules being consumed by larvae. These results provide possible candidates and soil-less method for the development and evaluation of alfalfa cultivars that may reduce the impacts of CRC root feeding and that offer an additional option for CRC management. Since the cancellation of broad-spectrum soil-active insecticides in alfalfa (Medicago sativa L.) production, clover root curculio (Sitona hispidulus F.) (CRC) larval root damage has increased. Current CRC management practices are limited in their ability to suppress larval feeding belowground. First, we field screened developmental alfalfa populations for CRC damage. Subsequently, we developed a soil-less arena to observe nodule feeding and development (head capsule width) of larvae in the lab. This method was used to evaluate five alfalfa populations (two CRC-susceptible (control) and three CRC-resistant populations) against larvae. Further, one CRC-resistant population paired with its genetically similar susceptible population were tested against adult leaf consumption and oviposition in the greenhouse. Field screening revealed that the alfalfa populations selected for little or no larval root feeding damage were more resistant to CRC larval feeding than their corresponding unselected cultivars and significantly more resistant than populations selected for susceptibility. The development of a soil-less arena provided a useful method for evaluation of root-larva interactions. Although larval development was similar across susceptible and resistant alfalfa populations, one CRC-resistant population (NY1713) displayed overall increased nodulation and, thus, had a significantly lower proportion of nodules consumed by larvae. Adult feeding and oviposition aboveground were similar across all populations tested. These results provide possible candidates and screening method for the development and evaluation of alfalfa cultivars that may reduce the impacts of larval feeding and that offer an additional option for CRC management.

Response of Soil pH and Nodulation of Three Chickpea Genotypes to Biochar and Rhizobium Inoculation

ABSTRACT Soils in the semi-arid regions such as north-eastern South Africa, where chickpea was recently introduced, are commonly characterized by poor fertility and low pH. Preliminary studies show that the crop has a huge potential in the region, but lack of nodulation has consistently been a problem. We assessed the response of soil pH and nodulation of three chickpea genotypes (ACC #4, ACC #5, and ACC #6) to biochar application (0, 10, and 20 t ha−1) and rhizobium inoculation (inoculated and uninoculated) in Thohoyandou (clay soil) and Nelspruit (loamy sand soil), South Africa in 2015 and 2016. Nodulation was assessed at flowering by determining the number of nodules per plant and nodule dry weight, and soil pH was analyzed after harvest in both seasons. Biochar increased pH by 0.7 (clay soils) and 0.7–0.8 (the more acidic loamy sand soils) pH units. Similarly, biochar increased nodulation in inoculated treatments in both locations and seasons, and this was mainly associated with the effect of biochar on soil pH. The increase in nodulation with inoculation varied amongst the genotypes. Clearly biochar and rhizobium inoculation may be crucial for improving soil pH and nodulation in chickpea cropping systems characterized by poor soils.

Seed Coating Formulations for Improving Rhizobia Survival, Growth, and Grain Yield of Common Bean

Coating legume seeds with Rhizobia have met a little success because of the difficulty in supporting bacterial survival on the seed coating agent. Accordingly, these studies aimed (i) to determine the best seed coating formulations to maintain the survival of Rhizobium phaseoli population on the surface of coated bean seed over a storage period of 0, 24, and 48 hours at 400C for laboratory trial, and (ii) to evaluate the best formulations for common bean growth and yield for field trial. Twelve seed coating formulations (SCFs) were used to coat garden bean seeds for the two studies. The results showed that four SCFs were the best for R. phaseoli survival throughout the storage period. They contained combinations of gum arabic and peat moss (100%), gum arabic and peat moss+biochar (25%:75%), carboxymethyl cellulose and peat moss (100%), and carboxymethyl cellulose and peat moss+biochar (25%:75%). These four Rhizobia seed-coating formulations also promoted the best common bean growth and yield based on nodule number, plant dry weight, and grain yield indicators. Overall, these studies suggest that the four SCFs promoted the highest increase in nodulation, plant biomass production, and grain yield due to their ability to maintain the highest survival of R. phaseoli population on the surface of coated bean seed.

Bioorthogonal click chemistries enable simultaneous spatial patterning of multiple proteins to probe synergistic protein effects on fibroblast function

Three biorthogonal click reactions, a photoinitiated thiol-yne reaction, an azide-alkyne cycloaddition, and a methyltetrazine-transcyclooctene Diels Alder, were used to independently control the presentation of several bioactive proteins to valvular interstitial cells (VICs) in hydrogel scaffolds. Tethered fibroblast growth factor (FGF-2) was found to suppress myofibroblast activation (from 48 ± 7% to 17 ± 6%) and promote proliferation (from 10 ± 2% to 54 ± 3%) at a concentration of 10 ng/mL. In the presence of the pro-fibrotic cytokine transforming growth factor-beta (TGF-β1), FGF-2 could protect the VIC fibroblast phenotype, even at much higher concentrations of TGF-β1 than that of FGF-2. With respect to the fibrocalcific VIC phenotype, TGF-β1 and bone-morphogenic protein-2 (BMP-2) were found to synergistically promote calcific nodule formation (a five-fold increase in nodules compared to TGF-β1 or BMP-2 alone). Exploiting the orthogonal click reactions, FGF-2, TGF-β1 and BMP-2 combinations were patterned into distinct regions on a hydrogel to control VIC activation and nodule formation. Cellular crosstalk between separate regions of the same scaffold was affected by the size of each region as well as the interfacial area between different regions. Collectively, these results demonstrate the versatility and robustness of a photoinitiated thiol-yne reaction to template pendant functionalities that allow for the bioconjugation of multiple proteins. This approach maintains protein bioactivity, providing an in vitro platform capable of achieving a better understanding of the complex mechanisms involved in tissue fibrosis.

High Maize Density Alleviates the Inhibitory Effect of Soil Nitrogen on Intercropped Pea

Nitrogen (N) fixation is essential in the development of sustainable agriculture, but nodulation of legumes is usually inhibited by N fertilization. In this study, we evaluated the increased density of intercropped maize (Zea mays L.) as a means to alleviate the inhibitory effect of soil mineral N on intercropped pea (Pisum sativum L.) and improve system performance. A field experiment was conducted in the Hexi Corridor region of northwestern China from 2012 to 2014. The experiment consisted of monoculture pea, monoculture maize, and a pea/maize strip-intercropping system. Two levels of N fertilization were evaluated in both cropping systems during the co-growth period of intercropping, i.e., 0 kg N ha−1 (N0) and 135 kg N ha−1 (N1), and three maize densities were evaluated with both levels of N fertilization in the intercropping system, i.e., 45,000 plants ha−1 (D1), 52,500 plants ha−1 (D2), and 60,000 plants ha−1 (D3). The application of N reduced the number of nodules of intercropped pea by 135% at D1 and by 9% at D2 compared to no application of N, in all the years examined. The alleviation of the inhibitory effect of soil mineral N on the nodulation of intercropped pea (Cis) was calculated as the percentage increase in nodulation with intercropping relative to monoculture for a given level of N fertilization. With the application of N, Cis was improved by increased intercropped maize density (D3 > D2 > D1) at all stages. The internal efficiency of nitrogen (IEN) of pea was improved with intercropping and, on average, was 19% and 12% greater at D3 than at D1 and D2, respectively. These results demonstrate that increased maize density can alleviate the inhibitory effect of soil N on the nodulation of pea and sustain the productivity of maize/pea intercropping while reducing N fertilizer requirements in arid regions.

Recombinants Rhizobacteria Enhanced Biological Control of Rhizoctonia solani infected Faba Bean

This study aimed to test the effect of Rhizobium recombinants on the vegetative growth and yield components of faba bean under biotic stress of Rhizoctonia solani. Tweleve transconjugants resulted from six crosses were evaluated for their antigonism against Rhizoctonia solani. The results showed variations in chitin hydrolysis after genome shortening. At the molecular level, the recipient strains of rhizobia showed more similarity with each other. However, the donar strains of Serratia and pseudomonas showed less similarity. Meanwhile , Rhizobium transconjugants genomes have a similar distribution of bands. Both transconjugants Tr 4 and Tr15 showed more genome size than the other ones due to high level of plasmid transfer. The same transconjugants recorded higher values of chitin hydrolysis zone due to higher expression of chitinase genes. Most transconjugants showed significant increase in nodulation above the uninoculated plants grown in the infected soil. Rhizobium inoculants improved the yield , chlorophyll concentration and NPK content of the plants grown in the soil infected with Rhizoctonia solani compared with uninoculated plants. The results indicated that Rhizobium inoculants improved the growth and yield of plants grown under biotic stress condition. In addition, improved rhizobia with chitinolytic enzymes producing genes could inhibit significantly the growth of pathogenic fungi.

Endophytic Fungus Drives Nodulation and N2 Fixation Attributable to Specific Root Exudates.

Endophytic fungi play important roles in the modification of ecosystem productivity; however, the underlying mechanisms are only partly understood. A 2-year field plot experiment verified that the endophytic fungus Phomopsis liquidambaris increased peanut (Arachis hypogaea L.) yields and significantly increased nodulation and N2 fixation regardless of whether N fertilizers were added. Root exudates collected from P. liquidambaris-colonized plants significantly improved nodulation and N2 fixation. Rhizosphere stimulation experiments further showed that colonized root exudates had significantly decreased soil nitrate (NO3-) concentrations, with decreased abundance and diversity of ammonia oxidizing archaea (AOA). In contrast, the abundance and diversity of diazotrophs significantly increased, and most diazotrophs identified were peanut nodulation-related strains (Bradyrhizobium sp.). P. liquidambaris symbiosis increased the expression of phenolic and flavonoid synthesis-related genes, and the derived phenolics and flavonoids could effectively increase the chemotaxis, biofilm formation, and nodC gene expression (nodulation-related biological processes) of the Bradyrhizobium strain. Metabolic pattern analysis showed that phenolics and flavonoids are more likely to accumulate to higher levels in the rhizosphere soil of peanuts colonized with P. liquidambaris Finally, a synthetic root exudate experiment further confirmed the underlying mechanisms for the P. liquidambaris-induced improvement in nodulation and N2 fixation, i.e., that the specific root exudates derived from P. liquidambaris colonization decrease nitrate concentration and increase the population and biological activities of peanut nodulation-related Bradyrhizobium species, which beneficially enhance peanut-Bradyrhizobium interactions. Therefore, this study is the first to provide new insight into a positive relationship between an exotic endophytic fungus, crop nodulation, and N2 fixation increase.IMPORTANCE Endophytic fungi play an important role in balancing the ecosystem and boosting host growth; however, the underpinning mechanisms remain poorly understood. Here, we found that endophytic fungal colonization with P. liquidambaris significantly increased the productivity, nodulation, and N2 fixation of peanuts through the secretion of specific root exudates. We provide a reasonable mechanism explaining how P. liquidambaris promotes peanut nodulation and N2 fixation, whereby the specific root exudates produced by P. liquidambaris colonization decrease rhizosphere soil nitrate (NO3-) and increase the population and biological activities of peanut-nodulating-related Bradyrhizobium strains, which is beneficial to enhancing the peanut-Bradyrhizobium symbiotic interaction. Our study provides reliable empirical evidence to show the mechanism of how an exotic endophytic fungus drives an increase in nodulation and N2 fixation, which will be helpful in erecting a resource-efficient and sustainable agricultural system.

Root nodulation in guar: Effects of soils, Rhizobium inoculants, and guar varieties in a controlled environment

Guar (Cyamopsis tetragonolobus L. Taub.) is a leguminous crop plant that produces a seed containing galactomannan gum, which is used in many applications as a lubricant, binder, thickener, and emulsifier, among other functions. A recent spike in worldwide guar consumption has been driven largely by the industrial uses of the gum. As a legume, the primary ecosystem service agricultural producers expect from guar is nitrogen fixation, but the common perception is that guar does not nodulate effectively. The objective of this replicated and repeated greenhouse study was to test the effects of contrasting soils, representing typical alkaline soils in which guar is cultivated worldwide, and Rhizobia inoculants on nodulation and plant growth characteristics in two guar varieties. In the study, abundant nodulation was observed. The soils had contrasting effects on nodulation, with a high nodule number of low weight (497 mg/24.3 nodules) in the clay loam and low nodule number of high weight (583 mg/8.64 nodules) in the sandy loam, but no effect of the inoculants was observed. The difference in nodule characteristics between the soils may have resulted from differences in indigenous Rhizobium population sizes and/or species available to associate with guar roots. The lack of inoculant effects may have resulted from high indigenous levels of Rhizobium in the soil and/or low concentrations of Rhizobium or uncompetitive Rhizobium delivered through the seed-applied inoculants. Based on the results of this study, we expect that guar will nodulate and fix nitrogen effectively in field conditions, given that these processes are not inhibited by exogenous factors, such as water stress. Achieving increases in nodulation and nitrogen fixation above baseline levels may require a concerted effort to develop effective inoculants for guar, which may offer a unique opportunity to expand biological nitrogen fixation in agriculture in semi-arid regions.

Reducing spatial variability of soybean response to rhizobia inoculants in farms of variable soil fertility in Siaya County of western Kenya

Soybean grain yields in sub-Saharan Africa have remained at approximately 50% below those attained in South America despite numerous efforts. A study was conducted in Siaya County (western Kenya) involving 107 farms with soils of different fertility status. The main objective was to test combinations of two inoculants (Legumefix and Biofix) and nutrient sources (Minjingu and Sympal) to raise soybean grain yields. Inoculation used Legumefix or Biofix with and without Minjingu or Sympal in a factorial design. There was soil acidity and a widespread deficiency of potassium, nitrogen, and phosphorus. Inoculation and nutrient source led to increases in nodulation and nodule occupancy. For grain yields the response varied from nil in some sites to high increases in others. Highest grain yields (3000–4000 kg ha−1) were obtained with Legumefix + Sympal (12% of the farmers testing it). The formulation of the nutrient source was important to meet other nutrient deficiencies in most of the soils. Farmers using Legumefix + Sympal require yield increases of 35% for profitability (Value cost ratio of 3) while farmers using Minjingu + inoculant require a yield increase of at least 68%. Inoculants used alone were most profitable but this is advisable only when farmers are too resource constrained to afford fertilizer. For sustainable yields Legumefix + Sympal or Biofix + Sympal were recommended.

English

Field experiments were carried out for three consecutive Rabi seasons (2011-12 to 2013-14) at Pulses Research Institute, Faisalabad to study the effect of bacterial inoculation on grain yield and quality of chickpea (desi). One variety (Pb-2008) and four advanced lines viz. D-03009, D-06002, D-06003 and D-06052 were tested with and without bacterial inoculation (Mesorhizobium ciceri, Pseudomonas spp. and Bacillus spp.). On a loamy soil (EC = 1.8 dS m-1, pH = 7.6), a consortium of three bacteria spp. was applied as seed coating at the time of sowing. The experiments were laid out in split plot design with three replications. Results showed a significant increase in nodulation (17.5%), plant height (4.0%), number of pods per plant (7.8%) and grain yield (7.5%) due to bacterial inoculation. The increase/decrease in the number of branches per plant (3.8%), 100 grain weight (1.9%), protein (- 4.5%), carbohydrate (0.0%), crude fiber (2.0%) and mineral matter (2.5%), remained statistically non-significant. The interaction among local cultivar / advanced lines and microbial inoculation was significant for improving grain yield. The advanced line D-06052 yielded with highest grains (2890 kg ha-1) due to bacterial inoculation. Hence, it can be argued that the bacterial inoculation positively influenced the grain yield and its components without fading the quality of produce. Bacterial inoculation is recommended for better chickpea yield.

The Endophytic Fungus Phomopsis liquidambari Increases Nodulation and N2 Fixation in Arachis hypogaea by Enhancing Hydrogen Peroxide and Nitric Oxide Signalling

The continuous cropping obstacles in monoculture fields are a major production constraint for peanuts. Application of the endophytic fungus Phomopsis liquidambari has increased peanut yields, and nodulation and N2 fixation increases have been considered as important factors for P. liquidambari infection-improved peanut yield. However, the mechanisms involved in this process remain unknown. This work showed that compared with only Bradyrhizobium inoculation, co-inoculation with P. liquidambari significantly elevated endogenous H2O2 and NO levels in peanut roots. Pre-treatment of seedlings with specific scavengers of H2O2 (CAT) and NO (cPTIO) blocked P. liquidambari-induced nodulation and N2 fixation. CAT not only suppressed the P. liquidambari-induced nodulation and N2 fixation, but also suppressed the enhanced H2O2 and NO generation. Nevertheless, the cPTIO did not significantly inhibit the induced H2O2 biosynthesis, implying that H2O2 acted upstream of NO production. These results were confirmed by observations that exogenous H2O2 and sodium nitroprusside (SNP) reversed the inhibition of P. liquidambari-increased nodulation and N2 fixation by the specific scavengers. The transcriptional activities of the symbiosis-related genes SymRK and CCaMK of peanut-Bradyrhizobium interactions also increased significantly in response to P. liquidambari, H2O2 and SNP treatments. The pot experiment further confirmed that the P. liquidambari infection-enhanced H2O2 and NO signalling pathways were significantly related to the increase in peanut nodulation and N2 fixation. This is the first report that endophytic fungus P. liquidambari can increase peanut-Bradyrhizobium interactions via enhanced H2O2/NO-dependent signalling crosstalk, which is conducive to the alleviation of continuous cropping obstacles via an increase in nodulation and N2 fixation.

Factors related to recurrence of the benign non-functioning thyroid nodules after percutaneous microwave ablation

Purpose: To determine the factors affecting the recurrence of the solitary benign thyroid nodules (BTN) after microwave ablation (MWA).Materials and methods: Between January 2013 and January 2015, a total of 110 patients with at least one solid thyroid nodule (solid component ≥ 80%) were enrolled. MWA was performed under continuous ultrasound (US) guidance. Before and during the follow-up, the thyroid nodule volume, thyroid function and cosmetic complaints were evaluated. Recurrence is defined by the new blood flow in the total ablation area or/and > 50% increase in nodule volume.Results: Almost all thyroid nodules were significantly decreased in size after MWA. After 12 months, the average volume of thyroid nodules was decreased from 12.6 ± 15.1 to 3.2 ± 5.7 ml. Of the total 110 patients, 16 cases had recurrence 12 months after MWA, and these patients had a larger initial volume than that of the non-recurrence patients (11.6 ± 14.9 vs. 23.9 ± 12.5, p < 0.01). The recurrence group also demonstrated more irregular blood vessels (1.8 8 ± 1.1 vs. 2.8 5 ± 1.3, p < 0.05), and a lower energy (1575.5 ± 674.3 J/ml vs. 1172.3 ± 454.2 J/ml, p < 0.01). In addition, 81.2% (13/16) of the patients in the recurrence group were adjacent to the vital structures, which is significantly higher than that of the non-recurrence group 28.7% (27/94) (p < 0.01).Conclusions: The US-guided MWA results in a satisfactory long-term outcome of the patients with a benign solitary thyroid nodule. We identified three risk factors for recurrence: initial volume, vascularity and the energy per 1 ml reduction in nodular volume.

COWPEA (VIGNA UNGUICULATA) CROPS IN AFRICA CAN RESPOND TO INOCULATION WITH RHIZOBIUM

SUMMARYCowpea (Vigna unguiculata L. Walp) is the most important food grain legume in Africa. Cowpea is nodulated by rhizobium bacteria in almost all soils of the tropics, but studies performed in the 1970s and 1980s in Nigeria suggested only modest responses of grain yield in the field to inoculation of selected rhizobium strains. More recently, experiments performed in Brazil have shown that cowpea responded to inoculation of rhizobium selected locally and grain yields increased by up to 30%. We tested some of the Brazilian strains on cowpea at a site in northern Mozambique and at several sites in Northern Ghana. At all sites phosphorus fertilizer (26 kg P ha−1) was added to all plots. At the site in Mozambique despite considerable damage to the crop by the parasitic yellow witchweed (Alectra vogelii), grain yields were more than doubled by inoculation of one of the Brazilian strains and reached 1.4 Mg ha−1. In on-station experiments conducted in 2012 in June and August in northern Ghana using the local cowpea variety Padi-Tuya as the test crop, nodule weight at 35 days after planting (dap) tripled with rhizobium strain BR 3299 (530 mg plant−1) in August with the other inoculants (BR 3267 and a mixture of BR 3267 and BR 3299) also increased nodule weight to over 300 mg plant−1. In the first on-station experiment, grain yields were doubled by the inoculation of any of the three rhizobium strains, and in the second experiment, significant increases in grain yield ranged from 39% to 57% and reached over 2.0 Mg ha−1. Similar increases in nodulation and grain yield due to inoculation were observed in 22 on-farm trials. Nitrogen fertilizer application promoted vegetative growth but did not increase grain yield and nodulation. Inoculating cowpea with highly effective rhizobium strains can therefore enhance grain yield of smallholder farmers in Africa.

Variability in colonization of arbuscular mycorrhizal fungi and its effect on mycorrhizal dependency of improved and unimproved soybean cultivars.

Breeding selection of germplasm under fertilized conditions may reduce the frequency of genes that promote mycorrhizal associations. This study was developed to compare variability in mycorrhizal colonization and its effect on mycorrhizal dependency (MD) in improved soybean genotypes (I-1 and I-2) with differential tolerance to drought stress, and in unimproved soybean genotypes (UI-3 and UI-4). As inoculum, a mixed native arbuscular mycorrhizal fungi (AMF) was isolated from soybean roots, showing spores mostly of the species Funneliformis mosseae. At 20 days, unimproved genotypes followed by I-2, showed an increase in arbuscule formation, but not in I-1. At 40 days, mycorrhizal plants showed an increase in nodulation, this effect being more evident in unimproved genotypes. Mycorrhizal dependency, evaluated as growth and biochemical parameters from oxidative stress was increased in unimproved and I-2 since 20 days, whereas in I-1, MD increased at 40 days. We cannot distinguish significant differences in AMF colonization and MD between unimproved and I-2. However, variability among improved genotypes was observed. Our results suggest that selection for improved soybean genotypes with good and rapid AMF colonization, particularly high arbuscule/hyphae ratio could be a useful strategy for the development of genotypes that optimize AMF contribution to cropping systems.