Nodule Dry Weight Research Articles

Symbiotic N2 fixation in cowpea varieties is markedly enhanced by inoculation with elite Bradyrhizobium strains

Because of its excellent ability to fix atmospheric nitrogen, cowpea [Vigna unguiculata (L.) Walp] makes a significant contribution to soil sustainability and productivity in the resource limited tropical regions. However, due to in part to ineffectiveness and limited availability of bio-inoculant, its symbiotic N contribution and yield remained low in the field. Therefore, this study examined the effect of elite cowpea infecting Bradyrhizobium strains (CP-24 and CP-37) on shoot biomass and symbiotic nitrogen contributions of four cowpea varieties (Keti, TVU, Black eye bean, and White wonderer trailing). For this a two-year field experiment was carried out at three sites using a factorial randomized complete block design with four replications. The natural abundance of the 15N technique was used to compute the symbiotic N contribution. Bradyrhizobium inoculation led to significantly higher nodule formation, % Ndfa, amounts of N fixed, and shoot biomass, demonstrating the effectiveness and ability of the strains to enhance soil fertility. Inoculating cowpea with CP-24 strain increased shoot N content, % Ndfa and N fixed by 40%, 15%, and 41%, respectively, in comparison to the un-inoculated control. Furthermore, the inoculant by variety interaction had a significant effect on nodule number, nodule dry weight, and amount of N fixed, with TVU and White Wonderer trailing in combination with CP-24 exhibiting the most outstanding performance. There was also a strong positive correlation between biomass accumulation and N fixed, as well as N fixed and seed yield. Therefore, Bradyrhizobium inoculation on cowpea varieties TVU and White Wonderer trailing with CP-24 strain is recommended at all three tested sites and similar agro-ecologies for improved symbiotic N contribution and associated yield advantage of cowpea. This study highlights that, the use of elite and crop specific Bradyrhizobium strains can boost symbiotic nitrogen contribution, soil fertility, and the yield performance of legumes. Thus, it helps resource-poor farmers who are suffering from rising mineral fertilizer cost to achieve food security while reducing climate change risks.

Isolation and characterization of mung bean (Vigna radiata L.) rhizobia in Myanmar

AbstractWe collected soil samples from six major mung bean cropping regions in Myanmar: Sagaing, Mandalay, Nay Pyi Taw, and Magway in the tropical savanna climate zone and Bago and Yangon in the tropical monsoon climate zone. All fields grew mung bean for at least 5 years and had no history of rhizobial inoculation. Mung bean ‘Yezin-11’, a popular cultivar in Myanmar, was inoculated with soil suspensions. From the nodules formed on the roots, we isolated 55 rhizobial strains. Identification of the isolates revealed the dominant species of indigenous rhizobia in each region. We identified 53 Bradyrhizobium strains and 2 Ensifer strains. Bradyrhizobium yuanmingense was dominant in the tropical savanna zone and Bradyrhizobium sp. (B. liaoningense or B. diversitatis) and B. centrosematis were dominant in the tropical monsoon zone. Principal component analysis indicates that the dominance of B. yuanmingense in the tropical savanna zone might be due to high concentration of NO3-N and P2O5 in the soil. It also indicates that the dominance of B. centrosematis in the tropical monsoon zone might be caused by drastically low pH and high concentration of NH4 in the soil. Bradyrhizobium centrosematis YGN-M9, B. yuanmingense SGG-M3, and Bradyrhizobium sp. BGO-M5 significantly increased nodulation (nodule number and nodule dry weight), acetylene reduction activity, and shoot dry weight, respectively, relative to Ensifer terangae MDY-M6. Co-inoculation with these three strains increased nodulation significantly compared with single inoculation of BGO-M5. The characterization of mung bean rhizobia and selection of microbial inoculant candidates will be useful for the development of microbial inoculants in Myanmar.

Relative multi-beneficial effect of MOs on plant health of chickpea (Cicer arietinum L. var. PG-186).

The phosphate solubilizing properties of Lysinibacillus macroides ST-30, Pseudomonas pelleroniana N-26, and Bacillus cereus ST-6 were tested for the chickpea crop of the Tarai region of Uttarakhand. These microbially inoculated plants have shown significant (p > 0.05) improvement in the plant health and crop health parameters, viz., root length, shoot length, fresh weight, dry weight, nodule number, nodule fresh weight, nodule dry weight, chlorophyll content, and nitrate reductase. The highest shoot length (46.10 cm) and chlorophyll content (0.57 mg g-1 fresh weight) were observed in ST-30 at 75 DAS with 20 kg P2O5/ha. Similarly, for plant P content, an increase of 90.12% over control was recorded in the same treatment. Treatments consisting of Lysinibacillus macroides ST-30 along with 20 kg/ha P2O5 were found to be most suitable as phosphatic fertilizer. Conclusively, sustainable agriculture practices in the Tarai as well as the field region may be developed based on a strategy of exploring microbial inoculants from the pristine region of the Western Himalayas. The presence and abundance of bacterial inoculants were confirmed through qRT-PCT. We conclude that the effective plant growth-promoting bacterium Lysinibacillus macroides ST-30 broadens the spectrum of phosphate solubilizers available for field applications and might be used together with 20 Kg/ha P2O5.

Nitrate Inhibits Nodule Nitrogen Fixation by Accumulating Ureide in Soybean Plants.

The mechanism by which nitrate inhibits nitrogen fixation in soybean (Glycine max L.) is not fully understood. Accumulation of ureide in soybean plant tissues may regulate the nitrogen fixation capacity through a feedback pathway. In this study, unilaterally nodulated dual-root soybeans prepared by grafting were grown in sand culture. They were subjected to the removal of the nodulated side roots, and were given either nitrate supply or no supply to the non-nodulated side roots for 3 days (experiment I). Additionally, they received nitrate supply to the non-nodulated side roots for 1-14 days (experiment II). The results showed that nitrate supply increased the levels of asparagine and ureide in soybean shoots (Experiment I). In Experiment II, nodule dry weight, nodule number, nodule nitrogenase activity, and nodule urate oxidase activity decreased significantly after 3, 7, and 14 days of nitrate supply. Ureide content in the shoots and nodules increased after 1, 3, and 7 days of nitrate supply, but decreased after 14 days of nitrate supply. There was a significant positive correlation between urate oxidase activity and nitrogenase activity. Hence, we deduced that nitrate supply increased the asparagine content in soybean shoots, likely inhibiting ureide degradation, which induced the accumulation of ureide in soybean shoots and nodules, and, in turn, feedback inhibited the nodule nitrogen fixation. In addition, urate oxidase activity can be used to assess the nitrogen fixation capacity of nodules.

Effect of Phosphorus levels with and without Phosphate solubilizing bacteria on growth, yield and quality of Cowpea (Vigna unguiculata) L.

A field experiment entitled “Effect of phosphorus levels with and without phosphate solubilizing bacteria on growth, yield and quality of cowpea (Vigna unguiculata L. Walp) in semi-arid region of South-Eestern Rajasthan was conducted during Kharif season of 2021 at the Experimental Farm of Agronomy, Mewar University, Gangrar, Chittorgarh (Rajasthan). The experiment consists of eight treatments, levels of phosphorus with and without PSB viz., 0, 20, 40 and 60 kg P2O5 ha-1, PSB, 20 kg P2O5 ha-1+PSB, 40 kg P2O5 ha-1 +PSB and 60 kg P2O5 ha-1 +PSB replicated four times laid down in RBD. Cowpea variety Pratap RC-19 was used with seed rate 15 kg ha-1. Growth attributes viz., plant height at 60 DAS and at harvest responded with 40 kg P2O5 ha-1 except 30 DAS where it responded with 60 kg P2O5 ha-1 over control. Primary and secondary branches per plant, number of trifoliate leaf of cowpea statistically significantly responded up to 40 kg P2O5. ha-1 at harvest. Similarly, root nodule number at 45 DAS responded up to 40 kg P2O5. ha-1 whereas nodule dry weight was responded up to 60 kg P2O5. ha-1 at 45 DAS over 40 kg, 20 kg P2O5 ha-1 and control. Yield attributing characters namely number of pods per plant and pod length were perceptibly increase, ed by application of 40 kg P2O5. ha-1 over 20 kg P2O5 ha-1 and control. Further, application of 60 kg P2O5 ha-1 remained statistically at par in enhancing yield attributes. 1000-grain weight, seeds per pod and harvest index was significantly higher up to 20 kg P2O5 ha-1 and control. Grain, straw and biological yields of cowpea perceptibly increased with the application of 40 kg and 60 kg P2O5. ha-1 but the higher dose of 60 kg P2O5 ha-1 remained statistically at par with 40 kg P2O5 ha-1. Improvement in N content both in grain and straw, P content in straw and K content both in grain and straw, protein content in grain and grain protein yield was significantly improved up to 40 kg P2O5. ha-1. P content in grain was responded with 60 kg P2O5 ha-1. Similarly, NPK uptake by both grain and straw and total uptake of nutrients (NPK)Nwas increased significantly under 40 kg P2O5. ha-1 over 20 kg P2O5 ha-1 and control. The dose of 60 kg P2O5 ha-1 remained statistically at par with 40 kg P2O5. ha-1 in enhancing gross and net returns and B:C over 20 kg P2O5 ha-1 and control.

Numerical Variables Analysis and Improving Phosphorus Use Efficiency in Groundnut with Microbial Cultures in Coastal Zone of Puducherry

Background: The precise application of phosphorus fertilizer is pivotal in determining Groundnut (Arachis hypogaea L.) productivity. The high demand of phosphorus for energy transfer molecules involved in nitrogen fixation makes it essential for leguminous crop. A field experiment was conducted at Perunthalaivar Kamaraj Krishi Vigyan Kendra, Puducherry during 2021 to 2023 to explore the performance of groundnut by employing an optimal combination of microbial culture alongside varying levels of phosphorus. Methods: The experiment was laid out in randomized block design with 10 treatments and replicated thrice. The treatments consisted of different doses of phosphorus (@ 20, 40 and 60 kg/ha) with and without seed treatment with DGRC culture. Result: The experiment results of the three years study revealed that a variable response of groundnut to P fertilizer rates and rhizobium inoculant on sandy loam soil in puducherry. P fertilizer rates combined with DGRC inoculant had a significant influence on growth, root nodule, nodule dry weight, pod and kernel yield. From this study, it may concluded that combined application of P fertilizer @ 60 kg/ha and seed treatment of DGRC culture inoculants @ 20 g/kg seed have the potential to increase the productivity and profitability of groundnut. Correlation and Regression analysis also indicated that the yield attributes had a positive impact on groundnut yield.

Assessment of the Influence of zaï, Stone Rows, and Organo-mineral Fertiliser on Soil Properties and Groundnut Yields Performances in Sudan Sahelian Zone of Burkina Faso

Groundnut occupies a vital position in oilseed crop production in Burkina Faso, with current production at 630,526 tonnes. However, its production faces threats from drought and low soil fertility. This study aims to determine the influence of zaï, stone rows, ridge tillage, and mineral fertilisation on soil health and on groundnut yields performances in Sudan Sahelian zone of Burkina Faso. Experimental treatments were distributed randomly following a Fisher block design, comprising four treatments and five replications, in the village of Sandogo. Data on soil properties, plant growth, and yields were analysed using variance analysis in R software. The results indicate significant influences of the treatments on carbon content, nitrogen content, phosphorus content, pH values, soil moisture content, soil carbon dioxide release, and soil macrofauna. Moreover, notable effects were observed on the number of nodules, drier nodule weight, number of leaves and branches, pod load, pod and straw yields, and the weight of 100-pods. The highest carbon content (0.857; 0.861%), nitrogen content (0.081%; 0.087%), phosphorus content (7.488; 7.735 mg.kg-1), pH values (6.43; 6.54), and soil moisture content (24.80; 25.27%) were recorded in the homogeneous group of zaï and zaï associated to stone rows. The highest carbon dioxide release (2863.33 ppm) was recorded in plots treated with stone rows. Ants were the most widely encountered macrofauna, whereas no earthworms were recorded. The highest performance in terms of the number of nodules (84.76; 87.88), dry nodule weight (0.0893; 0.0886 g/plant), number of leaves (40; 40), number of branches (6; 6), pod load (25; 25), weight of 100-pods (112.90; 111.98 g), straw yields (1673.28; 1664.87 kg.ha-1), and pod yields (2122.32; 2161.96 kg.ha-1) were achieved with zaï and zaï combined with stone rows. Zaï and zaï combined with stone rows can therefore be used as effective alternatives to improve groundnut production in the Sudan Sahelian zone of Burkina Faso in a context of climate change, while protecting the environment.

Yield Trait and Stability of Chickpea Genotypes for Intensification of Drought‐Prone Rice Fallows of South Asia

ABSTRACTThere is a need for increasing cropping intensity in South Asia including India to ensure food security of burgeoning population. Accordingly, increasing cropping intensity in rainfed rice fallows can be a futuristic strategy. Identification of suitable cultivar and exploration of genetic variability of specific crops/traits are imperative for genetic improvement, drought resistance and yield gain in rice fallows. We evaluated the morphophysiological, yield traits and stability of 15 chickpea genotypes in randomised complete block design for three consecutive years on a drought‐prone rainfed condition of Fluvisol in Kanpur, India. Among genotypes, ‘IPC 2014‐55’, ‘IPC 2015‐44’ and ‘IPC 2011‐92’ had 2%–10% higher relative water content (RWC) over ‘ICC‐92944’ (check cultivar). These genotypes did not differ for total chlorophyll content, root dry weight and nodule dry weight with ‘ICC‐92944’ and ‘KWR 108’ (wider adaptable cultivar of the region). The nitrogen balance index was higher in ‘IPC 2011‐92’, ‘IPC 2014‐88’ and ‘IPC 2014‐55’ by 5%–44% over check cultivar (p < 0.05). The membrane stability index was higher for ‘IPC 2014‐55’ (30%, p < 0.05) and ‘IPC 2011‐92’ (17%, p < 0.05) than ‘ICC‐92944’. ‘IPC 2011‐92’, ‘IPC 2014‐88’ and ‘IPC 2014‐55’ (3 years mean) had 3%–24% higher plant dry weight than ‘ICC‐92944’. Notably, ‘IPC 2014‐55’, ‘IPC 2015‐44’, ‘IPC 2014‐88’ and ‘IPC 2011‐92’ had higher yield attributes such as pods plant−1 by 9%, grain weight plant−1 by 13% and 100‐seed weight by 3% than ‘ICC‐92944’ and ‘KWR 108’ (mean of years). These genotypes had higher mean seed yield than ‘ICC‐92944’ by 23%–42% and ‘KWR 108’ by 7%–23% (p < 0.05). The yield of ‘IPC 2014‐55’, ‘IPC 2015‐44’, ‘IPC 2014‐88’ and ‘IPC 2011‐92’ were stable over years across variable soil and environmental condition as indicated by the genotype × year biplot. Membrane stability index, pods plant−1 and 100‐seed weight were the determinants for increased seed yield of chickpea under drought‐prone condition. Evidently, genotype ‘IPC 2014‐55’, ‘IPC 2015‐44’, ‘IPC 2014‐88’ and ‘IPC 2011‐92’ were better under rainfed rice fallows. These genotypes could be tested under specific drought condition for developing varieties and promoted in rice fallows of South Asia for yield advantage and drought resistance.

Mesorhizobia strain and chickpea variety drive phenotypic plasticity of plant growth and nodulation

Chickpea (Cicer arietinum) establishes symbiotic relationships with several Mesorhizobium species and the three-way interaction between chickpea variety, Mesorhizobium strain, and environment, drives plant growth and nitrogen fixation. Here we quantified the phenotypic plasticity for shoot dry weight, nodule dry weight, nodules per plant, nodule colour, symbiotic effectiveness, and nitrogen cost in a factorial experiment combining five chickpea varieties, seven Mesorhizobium strains and three photothermal regimes. Plant growth and nitrogen fixation traits varied with variety, Mesorhizobium strain, photothermal environment and their interaction. Phenotypic plasticity was larger for nodules per plant (7.3-fold) than for shoot dry weight (2.7-fold), verifying a hierarchy of plasticities between these traits. Strain-driven plasticity of plant growth and nitrogen fixation traits was larger than variety-driven plasticity for our combination of varieties, strains, and photothermal environments, with strain-driven phenotypic plasticity being 2.7-fold vs 1.4-fold for shoot dry matter, 2.5-fold vs 1.7-fold for nodule dry weight, 7.3-fold vs 2.1-fold for nodules per plant, 3.7-fold vs 1.7-fold for nodule color, 2.9-fold vs 1.6-fold for symbiotic effectiveness, and 2.3-fold vs 1.6-fold for nitrogen cost. Our study provides insights on the phenotypic plasticity of the legume-rhizobia interaction by considering the plants as part of the rhizobia environment and vice-versa.

Phosphate solubilizing bacteria, Pseudomonas aeruginosa, improve the growth and yield of groundnut (Arachis hypogaea L.).

For agricultural safety and sustainability, instead of synthetic fertilizers the eco-friendly and inexpensive biological applications include members of plant-growth-promoting rhizobacteria (PGPR) genera, Pseudomonas spp. will be an excellent alternative option to bioinoculants as they do not threaten the soil biota. The effect of phosphate solubilizing bacteria (PSB) Pseudomonas aeruginosa (MK 764942.1) on groundnuts' growth and yield parameters was studied under field conditions. The strain was combined with a single super phosphate and tested in different combinations for yield improvement. Integration of bacterial strain with P fertilizer gave significantly higher pod yield ranging from 7.36 to 13.18% compared to plots where sole inorganic fertilizers were applied. Similarly, the combined application of PSB and inorganic P fertilizer significantly influenced plant height and number of branches compared to sole. However, a higher influence of phosphorous application (both PSB and P fertilizer) observed both nodule dry weight and number of nodules. Combined with single super phosphate (100% P) topped in providing better yield attributing characters (pod yield, haulm yield, biomass yield, 1000 kernel weight, and shelling percentage) in groundnut. Higher oil content was also recorded with plants treated with Pseudomonas aeruginosa combined with single super phosphate (SSP) (100% P). Nutrients like nitrogen (N), phosphorous (P), and potassium (K) concentrations were positively influenced in shoot and kernel by combined application. In contrast, Ca, Mg, and S were found to be least influenced by variations of Phosphorous. Plants treated with Pseudomonas aeruginosa and lower doses of SSP (75% P) recorded higher shoot and kernel P. We found that co-inoculation with PSB and SSP could be an auspicious substitute for utilizing P fertilizer in enhancing yield and protecting nutrient concentrations in groundnut cultivation. Therefore, PSB can be a good substitute for bio-fertilizers to promote agricultural sustainability.

Screening for drought-tolerant mungbean root nodule bacteria with multiple plant growth promoting traits in Aridisol

Mungbean (Vigna radiata L. Wilczek) is an economically important legume crop grown across India. The growth and yield of the crop have been declining over the recent years due to climate change which leads to decrease in soil moisture. Applications of drought-tolerant plant growth-promoting (PGP) rhizobial strains have been found to enhance crop productivity under water deficiency. Therefore, the objective of this study was to screen the bacterial strains from the mungbean root nodule that may help in improving the plant growth under drought condition. Bacteria were isolated from mungbean root nodules and screened for in vitro drought-tolerance using different concentrations of PEG 6000 at 10, 20, 30 and 40 %, and temperature-tolerance at 30, 35, 40 and 45 °C. In primary screening, out of 98 root nodule bacterial isolates tested, only 25 % showed drought-tolerance at 40 % polyethylene glycol (PEG)-6000 while 22 % of bacteria survived at 45 °C. During secondary screening on combined stress-tolerance, only 8 % of isolates showed tolerance of 40 % PEG-6000 at 45 °C. The in vitro drought-tolerance of bacteria varied significantly according to their sampling region/district. Various PGP traits, i.e., nitrogen fixation, phosphate solubilization, and production of indole acetic acid, ammonia, and 1-aminocyclopropane-1-carboxylate (ACC) deaminase, were analyzed in isolated stress-tolerant bacteria, which may contribute towards stress-tolerance and crop productivity in mungbean. The most promising drought-tolerant nodule bacterial isolates were identified as Rhizobium sp. and Pseudomonas indica, respectively by 16S rRNA sequencing. Moreover, bacterial isolates MuJs52b, MuJs53b, MuJs72a and MuBk32b, which exhibited drought-tolerance of 40 % PEG-6000 and different PGP activities, were used as bioinoculant on mungbean plants grown under moderate to severe drought at 50 and 25 % of field capacity (FC) in pot experiment. Bacteria inoculated plants showed maximum increase in nodule dry weight (56.5 %) and shoot dry weight (87.5 %) per plant even under severe drought at 25 % FC. The results indicated that application of four potential nodule bacterial isolates, which were able to tolerate drought stress of 40 % PEG-6000, and having multiple PGP traits, showed stimulation of the mungbean growth even up to 25 % FC. These plant growth-promoting nodule bacterial strains may be used for the enhancement of mungbean crop productivity under drought stress and could be used as biofertilizer.

Long-term organic farming impact on soil nutrient status and grain yield at the foothill of Himalayas

This study aimed to document the effects of the long-term organic farming (OF) on soil quality, agronomical parameters, crop productivity, and food grain yield compared to the conventional farming (CF) system. The crop used in this study is chickpea (Cicer arietinum), and the field was located at Pantnagar, India, in the foothills of Himalayas. The organic farming approach involved utilizing a blend of farmyard manure and vermicompost, combined with a biopesticide comprising neem oil and cow urine. Chickpea grain micronutrient analysis was done via atomic absorption spectrophotometry. It was found that the physicochemical properties of soil in the organic plot were improved compared to the conventional counterpart. At the post-harvesting stage, the organically managed field had higher soil organic carbon than the conventional field (OF-0.93± 0.05%, CF-0.75 ± 0.12%), higher available nitrogen (OF-317 ± 11 kg/ha, CF-240 ± 22 kg/ha), and more available phosphorus (OF-37.4 ± 1.3 kg/ha, CF-25.2 ± 2.5 kg/ha). The agronomical parameters of the chickpea crop were better under organic cultivation, with a significantly high nodule number, nodule dry weight, and grains per pod. Hence, the grain yield of the crop was better under organic cultivation, with the yield of 1,048 kg ha−1, whereas it was 896.5 kg ha−1 for conventional cultivation. The Fe and Zn contents of organically produced chickpea grains were almost double of their conventional counterpart. Therefore, organic cultivation led to better soil fertility, chickpea grain yield, and nutrient status of the crop. It will be beneficial for the nutritious and sustainable production of chickpeas in Himalayan regions.

Root and shoot studies of summer cowpea (Vigna unguiculata) and baby corn (Zea mays) under intercropping system with different levels of fertility and stress-mitigating chemicals

An experiment was conducted during summer seasons of 2019 and 2020 at College of Agriculture (Agriculture University, Kota), Ummedganj, Rajasthan, to study the root and shoot of summer cowpea [Vigna unguiculata (L.) Walp.] and baby corn (Zea mays L.) under intercropping system with different levels of fertility and stress-mitigating chemicals. The experiment was laid out in a split-split plot design with 4 replications having 30 treatment combinations with 5 intercropping systems [sole cowpea; sole baby corn; cowpea + baby corn (2:1); cowpea + baby corn (3:1); and cowpea + baby corn (4:1)] in the main plot and 3 fertility levels, viz. 100; 125; and 150% RDF (Recommended dose of fertilizer) in subplot and 2 stress mitigating chemicals (0.5% CaCl2 and 1% KNO3 at flowering and pod development stage of cowpea) in sub-sub plot. Results revealed significant increase in shoot weight, root weight, root-to-shoot ratio, cowpea equivalent yield (CEY) and number and dry weight of nodules in 2:1 row cowpea + baby corn intercropping system over other row ratios. The 2:1 row ratio significantly increased root:shoot ratio of cowpea by 20.9, 15.2, and 7.3% over sole cowpea, 4:1 and 3:1 row ratio, respectively, and resulted in the highest root-to-shoot ratio for baby corn, recording 18.3, 14.5, and 6.8% increase over sole baby corn, 4:1, and 3:1 row ratios of cowpea and baby corn, respectively. Further shoot weight, root weight, root:shoot ratio in cowpea and baby corn, CEY and the number and dry weight of nodules in cowpea exhibited a notable increase in 150% RDF as compared to lower fertility levels (100 and 125% RDF). Applying 150% RDF resulted in a significantly higher root:shoot ratio for both cowpea and baby corn, with increases of 11.3 and 4.5% over 100 and 125% RDF for cowpea, and 11.6 and 5.5% over 100 and 125% RDF for baby corn, respectively. Foliar application of 0.5% CaCl2 at the flowering and pod-developing stages significantly augmented all the aforementioned parameters for both cowpea and baby corn.

Nutrient management for enhancing productivity of pigeonpea (Cajanus cajan) based intercropping system under rainfed condition

A field experiment was conducted during the rainy (kharif) season of 2011–12 and 2012–13 at Tirhut College of Agriculture, Dholi, Bihar, to study the effect of nutrient management for enhancing productivity of pigeonpea [Cajanus cajan (L.) Millsp.]-based intercropping systems. Pigeonpea + turmeric (Curcuma longa L.) intercropping system, recorded significantly higher pigeonpea yield (2.00 t/ha), pigeonpea-equivalent yield (4.79 t/ha), fruiting efficiency (18.8%), water-use efficiency (6.1 kg grain/ha/mm), production efficiency (18.0 kg/ha/day) and net re turns ( 106.32 ×10/ha) than pigeonpea + maize (Zea mays L.) intercropping and sole pigeonpea. However, pigeonpea + turmeric recorded lower benefit: cost (B: C) ratio than sole pigeonpea. Significantly higher B: C ratio was recorded under pigeonpea + sesame (Sesamum indicum L.) (2.32) and pigeonpea + urdbean [Vigna mungo (L.) Hepper] (2.31) intercropping systems than pigeonpea + maize, pigeonpea + turmeric and sole pigeonpea. Pigeonpea + maize recorded significantly lower NPK uptake by pigeonpea than sole pigeonpea and the other in tercropping systems. Pigeonpea + mungbean [Vigna radiata (L.) R. Wilczek] and pigeonpea + urdbean recorded significantly higher number and dry weight of nodules /plant than pigeonpea + maize. Application of 125% recom mended dose of fertilizer (RDF) recorded significantly higher number of branches and pods/plant, pigeonpea equivalent yield (3.39 t/ha), land-equivalent ratio (1.87), production efficiency (12.8 kg/ha/day), net returns ( 80.83 ×103/ha), benefit: cost ratio (2.17) and NPK uptake by pigeonpea than RDF and 75% RDF. Pigeonpea equivalent yield in pigeonpea + urdbean, pigeonpea + mungbean and pigeonpea + sesame intercropping sys tems, increased significantly with the increasing levels of fertilizer up to RDF, and further increase in fertilizer level did not show significant effect on pigeonpea-equivalent yield. However, it increased significantly up to 125% RDF in pigeonpea + maize and pigeonpea + turmeric intercropping systems. Pigeonpea + urdbean and pigeonpea + mungbean increased organic carbon, available N, P, K content of the soil than the other intercropping systems and initial soil value.

Enhancing intercropping sustainability: Manipulating soybean rhizosphere microbiome through cropping patterns

Understanding the responses of soybean rhizosphere and functional microbiomes in intercropping scenarios holds promise for optimizing nitrogen utilization in legume-based intercropping systems. This study investigated three cropping layouts under film mulching: sole soybean (S), soybean–maize intercropping in one row (IS), and soybean–maize intercropping in two rows (IIS), each subjected to two nitrogen levels: 110 kg N ha−1 (N110) and 180 kg N ha−1 (N180). Our findings reveal that cropping patterns alter bacterial and nifh communities, with approximately 5 % of soybean rhizosphere bacterial amplicon sequence variants (ASVs) and 42 % of rhizosphere nifh ASVs exhibiting altered abundances (termed sensitive ASVs). Root traits and soil properties shape these communities, with root traits exerting greater influence. Sensitive ASVs drive microbial co-occurrence networks and deterministic processes, predicting 85 % of yield variance and 78 % of partial factor productivity of nitrogen, respectively. These alterations impact bacterial and nifh diversity, complexity, stability, and deterministic processes in legume-based intercropping systems, enhancing performance in terms of yield, nitrogen utilization efficiency, land equivalent ratio, root nodule count, and nodule dry weight under IIS patterns with N110 compared to other treatments. Our findings underscore the importance of field management practices in shaping rhizosphere-sensitive ASVs, thereby altering microbial functions and ultimately impacting the productivity of legume-based intercropping systems. This mechanistic understanding of soybean rhizosphere microbial responses to intercropping patterns offers insights for sustainable intercropping enhancements through microbial manipulation.

NopAA and NopD Signaling Association-Related Gene GmNAC27 Promotes Nodulation in Soybean (Glycine max).

Rhizobia secrete effectors that are essential for the effective establishment of their symbiotic interactions with leguminous host plants. However, the signaling pathways governing rhizobial type III effectors have yet to be sufficiently characterized. In the present study, the type III effectors, NopAA and NopD, which perhaps have signaling pathway crosstalk in the regulation of plant defense responses, have been studied together for the first time during nodulation. Initial qRT-PCR experiments were used to explore the impact of NopAA and NopD on marker genes associated with symbiosis and defense responses. The effects of these effectors on nodulation were then assessed by generating bacteria in which both NopAA and NopD were mutated. RNA-sequencing analyses of soybean roots were further utilized to assess signaling crosstalk between NopAA and NopD. NopAA mutant and NopD mutant were both found to repress GmPR1, GmPR2, and GmPR5 expression in these roots. The two mutants also significantly reduced nodules dry weight and the number of nodules and infection threads, although these changes were not significantly different from those observed following inoculation with double-mutant (HH103ΩNopAA&NopD). NopAA and NopD co-mutant inoculation was primarily found to impact the plant-pathogen interaction pathway. Common differentially expressed genes (DEGs) associated with both NopAA and NopD were enriched in the plant-pathogen interaction, plant hormone signal transduction, and MAPK signaling pathways, and no further changes in these common DEGs were noted in response to inoculation with HH103ΩNopAA&NopD. Glyma.13G279900 (GmNAC27) was ultimately identified as being significantly upregulated in the context of HH103ΩNopAA&NopD inoculation, serving as a positive regulator of nodulation. These results provide new insight into the synergistic impact that specific effectors can have on the establishment of symbiosis and the responses of host plant proteins.

Optimizing Initial Nitrogen Application Rates to Improve Peanut (Arachis hypogaea L.) Biological Nitrogen Fixation

The application of nitrogen fertilizer is crucial to the growth and biological nitrogen fixation of peanut, especially in the seedling stage where nodules have not yet formed. However, it is still uncertain how much initial nitrogen fertilizer should be applied to promote peanut root growth, nodule formation, and biological nitrogen fixation (BNF). There, a 2-year pot experiment was conducted using Huayu 22 (HY22, large-grain cultivar) and Huayu 39 (HY39, small-grain cultivar) as experimental materials to research the effects of different initial nitrogen fertilizer application rates on peanut root growth (root weight, root length, root mean diameter, root activity) and biological nitrogen fixation capacity (nodule number, nodule weight, biological nitrogen fixation, and nitrogen fixation potential per plant). N0, as control, four initial nitrogen fertilizer application rates were established: 15 kg·hm−2 (N15), 30 kg·hm−2 (N30), 45 kg·hm−2 (N45), and 60 kg·hm−2 (N60). The present results showed that the nodule number, nodule dry weight, nitrogenase activity, and biological nitrogen fixation of the HY22 cultivar under the N15 treatment were higher compared to those under other treatments over the two growing seasons. In addition, the cultivar of HY39 treated with the N15 treatment also increased the nitrogen fixation potential per plant and BNF relative to other treatments. Although the application of 60 kg·hm−2 nitrogen increased the root surface area and root volume, it decreased the nitrogenase activity, nodule dry weight, and nitrogen fixation potential per plant of HY22 and HY39 varieties in both growing seasons. Above all, an initial nitrogen application of 15 kg·hm−2 may be the optimal treatment for promoting peanut nodule formation and biological nitrogen fixation.

Evaluation of Rhizobial Inoculation in Comparison to Urea Fertilizer Application of Vegetable Bean (<em>Phaseolus vulgaris</em> L)

A field trial was conducted to evaluate the effects of Rhizobium inoculation in comparison to nitrogen fertilizer (NF) application on vegetable bean in the Ankumbura area, Kandy district during the Maha 2018/19 season. Six treatments were employed comprising four NF levels (55, 110, 165, and 220 kg urea/ha), rhizobium inoculation without NF, and control with neither NF nor inoculant. The treatments were set out in a randomized complete block design with three replicates. Four NF levels were 25%, 50%, 75%, and 100% of the recommended level for vegetable bean by the Department of Agriculture (DOA). All the treatments received potassium and phosphorous according to DOA recommendations. Pod yield/m2, growth parameters, several nodule parameters, and weed biomasses were recorded. Total yield (t/ha) was calculated based on the pod harvest. A yield versus fertilizer response curve was developed using calculated yield data. The highest total yield (3.03t/ha) with the application of 220kg/ha of urea was not significantly different from the yield produced under inoculation without NF (2.93 t/ha). This implies that inoculation facilitates a possible replacement of NF. Number of root nodules (30) and number of leaves (36) were significantly higher with inoculation. Higher levels; of 75% and 100% of recommended NF reduced nodule dry weight. Pod length, diameter, and dry weight with 100% and 75% NF levels were not significantly different (p<0.05) from those with inoculation. The highest pod N-yield (0.0586 g) and shoot N-yield (0.253 g) were recorded with inoculation and 220kg/ha urea application respectively. Weed biomass was significantly reduced (70%) with inoculation compared to the highest NF treatment. The results indicate a potential avenue to decrease the need for chemical nitrogen fertilizer and use inoculation to manage weed growth in vegetable beans in the Ankumbura area.

High efficient broad-spectrum Bradyrhizobium elkanii Y63-1

Soybean (Glycine max), the primary source of high-quality plant protein, plays a crucial role as a grain and oil crop in China. Harnessing the full potential of symbiotic nitrogen fixation in soybean production holds immense significance for agriculture and ecology alike. Zhongdou 63, a newly developed early-maturing summer soybean cultivar in 2021, exhibits remarkable traits such as high yield, superior quality, multi-resistance, and wide adaptability. In this study, eight distinct rhizobia strains from diverse regions were meticulously screened to identify highly effective strains specifically suited for Zhongdou 63. The aboveground biomass, plant height, chlorophyll content, root length, nodule number, and nodule dry weight of Zhongdou 63 were measured and the data were subjected to statistical analysis. The results demonstrated that Y63-1 is a predominant strain of Zhongdou 63. Subsequently, we conducted further investigations on the broad-spectrum nodulation characteristics of Y63-1. Ten representative soybean cultivars were individually inoculated with Y63-1 and subsequently analyzed for nodule numbers and nodule dry weight in their symbiotic systems with rhizobia. The findings revealed that Y63-1 effectively formed nodules with all ten soybean varieties tested. In summary, our current study identified highly efficient broad-spectrum Bradyrhizobium elkanii strain Y63-1 as the predominant strain in Zhongdou 63 and provided a theoretical foundation for enhancing yield potential not only in Zhongdou 63 but also in other varieties through inoculation with highly efficient rhizobia in production.

Effect of Integrated Application of Bio-Fertilizer and Soil Amendments on Growth Parameters of Groundnut (Arachis hypogaea L.)

The pot experiment entitled “Effect of integrated application of bio-fertilizer and soil amendments on Growth parameters of Groundnut (Arachis hypogaea L.)’’ was conducted at the Research Farm of School of Agriculture, ITM University, during kharif season 2022. The soil of the experimental field was sandy loam, having a pH of 8.13, EC of 0.54 ds m-1, organic carbon 0.40%, available N, P, K of 180, 11.09 and 283.40 kg ha-1 respectively and exchangeable Ca+Mg of 1.5 me 100 g-1soil. The pot experiment was laid out in CRD (Completely Randomized Design) with six treatments and six replications. The treatment combinations were: T1- Control, T2- Recommended Dose of Fertilizer (N, P2O5 and K2O @ 20, 40 and 20 kg ha-1 respectively), T3- FYM (10 t ha-1), T4- Rhizobium (Bradyrhizobium japonicum) @ 200 gm 10 kg-1 seeds, T5- RDF + Rhizobium, T6- Rhizobium + FYM. The nodulation (number of nodules and nodules dry weight) was increased with combine application of rhizobium inoculation and FYM over the time (30 and 60 DAS) followed by RDF and rhizobium inoculation. The growth attributes viz. plant biomass, shoot length, root length was significantly improved with the integration of bio-fertilizer, FYM and inorganic fertilizers. The highest result for plant biomass (22.34 gm plant-1) and shoot length (21.78 cm) were recorded in rhizobium inoculation and FYM treatment combination but root length (8.87 cm) was recorded highest in combine application of RDF with rhizobium. Application of rhizobium with FYM (25.74 gm pot-1) produce the highest pod yield followed by RDF and rhizobium (23.65 gm pot-1) combination. The combination of RHZ + FYM has much more favorable results on growth and yield of groundnut and it also enhance the nodulation.