Paper Towel Method Research Articles

Enumeration of Genetic Variability Parameters and Association among Early Seedling Growth Parameters under Polyethylene Glycol (PEG) induced Osmotic Stress in rabi Sorghum (Sorghum bicolor (l.) Moench)

Aims: The research aims to explore the variability within diverse rabi sorghum germplasms and identify the relationships among different early seedling growth traits. This will provide valuable insights for future breeding programs, aiding in the development of resilient sorghum varieties that can contribute to improved food security and agricultural sustainability. Study Design: The study was conducted by employing factorial complete randomized design (FCRD) with two replications. Where, two factors was considered, genotype as first factor and PEG concentration as second. Place and Duration of Study: The experiment was conducted during rabi season of 2023 at University of Agricultural Sciences Dharwad, Karnataka. Methodology: A total of 156 germplasm lines of rabi sorghum were assessed in vitro for early seedling growth characteristics, including germination percentage, shoot length, root length, seedling dry weight, and seedling vigor indices I and II, under both control and osmotic stress conditions induced by polyethylene glycol (PEG). Osmotic stress was induced by dissolving PEG 6000 in distilled water to achieve the desired concentration. The germplasm lines were then subjected to germination and early growth under these conditions using the paper towel method. The genetic variability parameters for each trait were quantified to examine the degree of variability in the material used, and correlation analysis was performed to understand the relationships among the traits studied. Results: The variance analysis showed highly significant differences among genotypes, treatments, and the genotype-by-environment (G×E) interactions. Genetic variability parameters revealed considerable variability across all traits studied, which tended to increase with higher stress levels. Moderate to high GCV and PCV was observed for all the traits studied. Correlation analysis demonstrated a strong, significant positive relationship among all seedling parameters, except between root length and shoot length, as well as between shoot length and germination percentage under control conditions. Conclusion: The study emphasizes the effect of osmotic stress on the early vigor and growth of sorghum seedlings. The findings reveal significant variability in seedling traits, suggesting that selection can be employed for genetic enhancement of these traits. Correlation analysis identified specific traits or combinations of traits that should be considered when selecting genotypes tolerant to osmotic stress conditions. These findings offer great potential to guide and improve selection and breeding programs focused on enhancing drought tolerant sorghum varieties.

Study on effect of plant growth promoting rhizobacteria on sorghum (Sorghum bicolor L.) under gnotobiotic conditions.

The rhizosphere is enriched with diverse microflora, allowing for delving prospective microorganisms to enhance crop growth and yield for varied soil conditions. Demand for millet growth-promoting microorganisms is a contemporary need for dryland agriculture. Therefore, a detailed survey was conducted in northern Karnataka, India, to identify the millet growing areas, particularly sorghum. The rhizobacteria from the sorghum (Sorghum bicolor L.) were assessed for promoting seed germination using the paper towel method and classified based on their efficiency. The elite isolates were positive for indole-3-acetic acid (IAA), gibberellic acid (GA), phosphate, zinc oxide solubilization, and hydrogen cyanide (HCN) production. The test isolates were antagonistic to Macrophomina phaseolina and Fusarium sp. and inhibited completely. Further evaluation of the cultures on sorghum growth-promoting attributes under pot culture conditions showed that the plants inoculated with PG-152 (Bacillus subtilis) recorded the highest plant height, chlorophyll content, root dry weight, shoot dry weight, and total dry weight under ideal conditions of fertilization. Two isolates, namely, PG-152 and PG-197, performing superior under pot culture conditions, were identified as Bacillus subtilis and PG-197 as Enterobacter sp., respectively, using 16S rDNA analysis. The sequences were allowed to screen open reading frames (ORF) and found several ORFs in Enterobacter cloacae and Bacillus subtilis, respectively. This study found that the rhizosphere is vital for identifying prospective isolates for biocontrol and plant growth-improving microorganisms.

Synthesis and application of biodegradable seed coatings to assess the infestation of chickpea (Cicer arietinum L.) seeds by pests

Pulses such as chickpeas face significant damage caused by pests during their growth and storage. The overuse of synthetic pesticides on seeds requiring several cycles of active ingredient applications results in increased expenses and environmental risks by contaminating soil, water, and air. These risks of seed damage without use of harmful pesticides can be reduced by coating the seeds with biodegradable seed coatings. The objective of the study was assessing the effectiveness of biodegradable seed coating in managing stored grain pests and to examine its effects on the germination of chickpeas. For this study chickpea (Cicer arietinum L.) seeds were coated with biodegradable coatings like polyvinyl alcohol with multinutrients, neem oil, chitosan and mucilage-starch nanocrystals. The characterization of coatings was carried out using Fourier Transform Infrared Spectroscopy, X-ray Diffraction and Scanning Electron Microscope. Germination of coated and uncoated chickpea seeds was observed by paper-towel method after 5 and 10 days. Chitosan coated seeds had greatest root length (3.10 ± 0.05 cm), shoot length (3.93 ± 0.08 cm), dry weight (0.24 ± 0.05 g), fresh weight (0.43 ± 0.05 g), germination rate (98.87 %) and vigour index (639.09 ± 0.05) followed by polyvinyl alcohol with multinutrients coated seeds, mucilage-starch nano crystals coated seeds and control group after ten days. The lowest root length (0.97 ± 0.14 cm), shoot length (1.53 ± 0.12 cm), dry weight (0.1 ± 0.005 g), fresh weight (0.21 ± 0.14 g), germination rate (65 %) and vigour index (163.75 ± 4.72) were displayed by neem oil-coated seeds. The impact of stored grain pests was evaluated and it was shown that neem oil had the highest efficacy in controlling pulse beetle infestations followed by chitosan, polyvinyl alcohol with multinutrients and mucilage-starch nano crystals. Neem oil coating enhanced pest mortality by 95 % after 15 days, reduced seed damage by 16.3 % and minimized seed weight loss by 10.6 % after 30 and 45 days. Biodegradable seed coating is a cost-effective and environment friendly way to improve seed performance and protect crops sustainably.

Isolation and characterization of native antagonistic rhizobacteria against Fusarium wilt of chilli to promote plant growth.

In the eastern coastal regions of Odisha, wilt caused by Fusarium oxysporum f. sp.capsici is an extremely damaging disease in chilli. This disease is very difficult to manage with chemical fungicides since it is soil-borne in nature. The natural rhizosphere soil of the chilli plant was used to isolate and test bacterial antagonists for their effectiveness and ability to promote plant growth. Out of the fifty-five isolates isolated from the rhizosphere of healthy chilli plants, five isolates, namely Iso 01, Iso 17, Iso 23, Iso 24, and Iso 32, showed their highly antagonistic activity against F. oxysporum f. sp. capsici under in vitro. In a dual culture, Iso 32 (73.3%) and Iso 24 (71.5%) caused the highest level of pathogen inhibition. In greenhouse trials, artificially inoculated chilli plants treated with Iso 32 (8.8%) and Iso 24 (10.2%) had decreased percent disease incidence (PDI), with percent disease reduction over control of 85.6% and 83.3%, respectively. Iso 32 and Iso 24 treated chilli seeds have shown higher seed vigor index of 973.7 and 948.8, respectively, as compared to untreated control 636.5. Furthermore, both the isolates significantly increased plant height as well as the fresh and dry weight of chilli plants under the rolled paper towel method. Morphological, biochemical, and molecular characterization identified Bacillus amyloliquefaciens (MH491049) as the key antagonist. This study demonstrates that rhizobacteria, specifically Iso 32 and Iso 24, can effectively protect chilli plants against Fusarium wilt while promoting overall plant development. These findings hold promise for sustainable and eco-friendly management of Fusarium wilt in chilli cultivation.

Bio-efficacy of seed dressing fungicides and bio-agents on seed borne fungal infections and seed quality of greengram

A laboratory experiment was conducted during summer-2021 at Department of Seed Science and Technology, University of Agricultural Sciences, Dharwad. The experiment was laid out in completely randomized design consists of eight treatments including the seed treatment with different seed dressing fungicides and bio-agents in greengram with each replicated four times in paper towel method and recorded the the influence of treatments on seed quality attributes of greengram. Among the different treatments, the seed treatment with Mancozeb 50% WP+ Carbendazim 25% WS (Sprint) @ 2g/kg recorded significantly highest germination (84.67%), lower seed infection (12.00%) and showed 13.48 per cent increase in germination and 44.67 per cent decrease in infection over control. The seed treatment with Trichoderma harzianum @ 10 g /kg seeds (T6) recorded the highest mean shoot length (24.3 cm) and mean root length (13.42 cm) followed by Mancozeb 50% WP+ carbendazim 25% WS (Sprint) @ 2g/kg seeds (23.1 cm) and 13.43 cm root length and these are found on par with each other. The seed treatment with Mancozeb 50% WP+ carbendazim 25% WS (Sprint) @ 2g/ kg seeds (T3) recorded significantly highest seedling vigour index (3098) and Trichoderma harzianum @ 10g /kg seeds (T6) recorded 3025 and both are found on par with each other and are followed by seed treatment with carbendazim 50% WP @ 2g/kg seeds (2942), Thiophanate methyl + pyraclostrobin (Xelero) @ 2g/kg seeds (2678). Mancozeb 50% WP+ carbendazim 25% WS (Sprint) performed better in controlling seed borne infections and thus enhanced seed quality parameters of greengram. Among bioagents Trichoderma harzianum can be predominantly used for seed treatment of greengram against seed borne fungal infections.

Studies on Association of Seed Borne Mycoflora in Different Varieties of Black Gram [Vigna mungo (L.) Hepper] by Incubation Methods

The present study was conducted to detect and identify seed-borne pathogenic fungi in some different varieties of black gram and their effect on seed germination. Six varieties of black gram (Indira urd-1, Pratap-1, KU-96, TPU-4, TIU-22) and local variety collected from village for experiment. The Eleven seed associated mycoflora recorded were Aspergillus flavus Aspergillus niger, Fusarium spp., Alternaria spp., Rhizopus spp., Penicillium spp., Curvularia spp., Cladosporium spp., Colletotrichum spp., Chaetomium spp. and Trichoderma spp. were detected and identified from the seeds of different varieties of black gram by using the standard blotter method, agar plate method, 2,4-D blotter method, roll paper towel method and deep freeze method. In all these methods, poor germination percentage was recorded in local variety, may be due to the presence of seed associated mycoflora with maximum frequency, whereas KU-96 variety has most extreme germination percentage due to the minimum frequency of seed associated mycoflora as compared to other varieties of black gram taken in the examination.

Identification on seed associated mycoflora of sesame genotypes

Seed mycoflora of 165 genotypes of sesame in (AVTs & IVTs) were detected using seed health testing methods viz., paper towel method, standard blotter method, and standard agar plate method and six distinct fungi viz.,Alternaria, Macrophomina, Fusarium, Aspergillus, Penicillium, and Rhizopus spp. were detected. In the three methods employed to identify seed mycoflora the standard blotter method has identified the maximum number of seeds infected by fungi compared to paper towel method and standard agar plate method. After a few days of germination, it was observed that the majority of the seeds were infected with disease, which hampered normal seedling growth and resulted in abnormal and rotted seedlings.

Antibacterial and plant growth promoting attributes of Limosilactobacillus sp. MYSN3 isolated from noni fruit

The aim of the study was to determine the antibacterial, plant growth promotion and bio-control activity of Limosilactobacillus sp. MYSN3 isolated from noni fruit (Morinda citrifolia). The noni fruit yielded eight distinct isolates and one effective isolate MYSN3 was chosen considering their antibacterial activity for further studies. The isolate MYSN3 recorded good inhibitory effect toward the tested plant pathogenic bacteria. The CFS of MYSN3 showed 69.12, 69.98 and 63.60 % inhibition against, Pectobacterium carotovorum sub sp. carotovorum, Ralstonia solanacearum and Xanthomonas oryzae pv. oryzae respectively in microplate assay. The isolate MYSN3 was identified as Limosilactobacillus sp. with accession number OL347895 and was verified using 16sRNA gene sequencing and had 95.23 % similarity with the earlier deposited sequence of Limosilactobacillus sp. - KJ865402. The effective isolate MYSN3 was characterized for growth promotion in plants and biological control attributes. Isolate MYSN3 showed IAA production (35.18 µg/ml), gibberellic acid production (23.45 µg/ml), solubilization of phosphate, potash, zinc and silicon and gave positive outcomes for protease and siderophore production and negative for cellulose degradation activity, HCN production activity and amylase activity. Seed treatment with Limosilactobacillus sp. MYSN3 greatly enhanced the standard of seed germination and seedling vigour of tomato by paper towel method and significantly increased plant height of tomato, chilli and okra under glasshouse condition when compared to control. The findings of the current research revealed that isolated Limosilactobacillus sp. MYSN3 possess promising antibacterial activity, plant growth promoting characteristics and bio-control traits. The potentiality of the isolate as bioinoculants and bio-control agents deserves further investigation.

Studies on Seed Borne Mycoflora of Soybean Seeds by Incubation Methods

The present study was conducted to detect and identify seed-borne pathogenic fungi in some soybean varieties and their effect on seed germination. Six varieties of soybean seed samples viz.JS 95-60, JS 97-52, RSC 10-46, RSC 10-71, CG Soya-1 and local variety were selected for the experiment. Twelve seed-borne mycoflora viz. Aspergillus flavus, Aspergillus niger, Alternaria spp., Cladosporium spp., Curvularia spp., Rhizopus spp., Trichoderma spp., Rhizoctonia spp., Nigrospora spp., Macrophomina spp., Fusarium spp. and Penicillium spp. were detected and identified from the seeds of six soybean varieties by using the standard blotter method, agar plate method, 2,4-D blotter method, roll paper towel method and deep freeze method. The seed sample of local variety recorded the highest percentage of mycoflora with the lowest germination percentage, whereas CG Soya-1 variety found as the least percentage of mycoflora with the highest germination percentage compared to other varieties of soybean taken in the study. Among all of the incubation methods, the agar plate was found as the most effective in detecting seed-related mycoflora, on soybean seeds.

In vitro evaluation of seed dressing fungicides against seed borne diseases ofBt cotton by paper towel method

The research experiment was conducted in laboratory during 2020 to test the efficacy of different seed dressingfungicides against seed borne fungal infections in Bt cotton (DCH-32) by using paper towel method. The results of theexperiment revealed the least per cent seed infection of 9.33 per cent was noticed in seed treatment with carboxin 37.5% WS+ thiram 37.5% WS @ 2 g/ kg of seed and next best treatment was seed treatment with penflufen 13.28% w/w FS +trifloxystrobin 13.28% w/w FS @ 2 g/ kg of seed with seed infection of 12 per cent as compare to control with per cent seedinfection of 32.67

Viability of seeds of two varieties of Coffea arabica L. using different pretreatments in the tetrazolium test

This research attempted to determine the efficacy of the tetrazolium test in the evaluation of the seed viability of two varieties of Coffea arabica L. (‘Castillo’ and ‘Cenicafé’). The fruits were obtained from crops located in the municipalities of Salazar de las Palmas and Arboledas (Norte de Santander - Colombia). The test was carried out with embryos manually extracted from the seeds using tweezers. Three pretreatments were established: distilled water, sodium hypochlorite (2.5 %), sucrose (10 %), and a control (no pretreatment). Embryos were placed in a cysteine solution (0.5 %) to prevent oxidation, then immersed in tetrazolium solutions with concentrations of 0.035 %, 0.075 %, and 0.1 % for a period of 6, 9, and 12 hours in darkness. The results of the viability test were validated with seed germination, using the wet paper towel method in darkness. The best viability percentages were found with the application of sodium hypochlorite (NaClO 2.5 %), with a high correlation with the germination percentage. The use of pretreatments improved the efficiency of the viability test and allowed the use of low concentrations of the reagent (0.035 %), giving the farmer a quick and less expensive alternative to determine germination capacity.

Detection of Xanthomonas oryzae pv oryzae in BLB Paddy Seed Samples from Endemic Regions of Telangana State, India

Bacterial Leaf Blight disease (BLB) in rice caused by Xanthomonas oryzae pv oryzae (Xoo), is one of the most economically important diseases causing epidemics globally, resulting in severe crop losses of 50% in addition to affecting the seed quality in Asia. In the present study, ten BLB affected paddy seed samples were collected during Kharif, 2021-22 from the farmer's fields of major BLB endemic districts viz., Nizamabad and Khammam of Telangana state. The collected BLB seed samples were subjected to different standard seed health tests (ISTA, 1996) for detection and isolation of Xoo. Among the different methods evaluated, the detection of Xoo from BLB affected seed samples was high in the Agar plate method followed by the test tube water agar method. However, the component plating method revealed that, of the different seed components, the per cent recovery of Xoo was high from the embryo followed by lemma, palea and endosperm indicating the systemic type of infection of Xoo. Further, the results of the paper towel method stated that of the ten BLB affected paddy seed samples collected, the seed samples of Govuru village (Nizamabad district) and Rejarla village (Khammam district) have recorded below Indian Minimum Seed Certification Standards i.e 77.00% and 79.25% of per cent seed germination compared to the seed samples of other locations.

Blackgram-Macrophomina phaseolina Interactions and Identification of Novel Sources of Resistance.

Macrophomina phaseolina, a fungus that causes dry root rot, is a relatively new threat to blackgram in South Asia. Because this pathogen is a polyphagic necrotroph, it remains viable in the soil for several years, making disease management challenging. One of the most economical methods for managing dry root rot in blackgram is through an integrated approach that uses resistant varieties. This study examined M. phaseolina associated with dry root rot in blackgram and screened 41 blackgram genotypes for dry root rot resistance. The present work also characterized morphological features and internal transcribed sequence regions of the nuclear rDNA operon to identify M. phaseolina from blackgram. Evaluation of the 41 blackgram genotypes against M. phaseolina by the paper towel technique identified two genotypes, CO-5 and IPU 07-3, with dry root rot resistance (disease scores: ≤3) and 18 genotypes with moderate resistance (disease scores: >3 to ≤5). Five genotypes with disease scores <4.0 and two susceptible genotypes were reevaluated using the paper towel method, which revealed moderate resistance reactions of CO-5, IPU 07-3, and MASH 1-1. To confirm dry root rot resistance of these seven genotypes, further screening was done in a greenhouse using the sick pot assay. Results revealed moderate resistance of CO-5, IPU 07-3, and MASH 1-1 genotypes. As compared with susceptible check (VO 2135-B-BL), CO-5 consistently excelled in plant survival with 13.4% disease incidence, followed by IPU 07-3 (16.7%) and MASH 1-1 (19.9%). Therefore, these three genotypes can be used as parents in blackgram breeding programs for developing blackgram cultivars with improved dry root rot resistance.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Phenotypic evaluation of seedling vigour-related traits in a set of rice lines

Under the changing climatic conditions, depleting nutrients and water scarcity, the dry-direct seeded rice (DDSR) with an aerobic system of cultivation is gaining ground in India. The uniform establishment ofseedlings is critically dependent on the seedling vigour and high seedling vigour provides better uptake of nutrients with uniform plant growth. With an aim to identify rice lines exhibiting high seedling vigour traits, we phenotyped the seedling vigour index-related traits viz., germination percentage (GP), mesocotyl length (ML), coleoptile length (CL), root and shoot fresh and dry weights in a set of rice lines consistingof introgression lines, landraces, mutant lines and popular varieties using the paper towel method. ANOVA revealed high significant variation for all the traits including seedling vigour index-I (SVI-I) and seedling vigour index-II (SVI-II). Significant positive intercorrelation was recorded between two sub-traits for establishment of seedling viz. coleoptile length and mesocotyl length. The rice lines viz., ATR-486, ATR-473, ATR-385, ATR-279, ATR-472, ATR-397, ATR-275, KK-12 and ATR-387 exhibited comparatively higher CL, ML, SVI-I and SVI-II than all the checks used in the present study. The identified lines exhibiting better seedling vigour traits are promising genetic resources that can be deployed in breeding programs for improving adaptability under DDSR conditions.

Evaluation of Bioagents as Seed Treatment on Dominant Seed Mycoflora of Chilli Var. Gvc 111 In Vitro

Study to check the efficacy of seed treatment by bioagents on the seed germination and vigour by inhibiting the most dominant seed mycoflora (A. niger, Colletotrichum sp. and Fusarium sp.) of chilli variety GVC 111 was carried out by paper towel method in vitro. Treatment of seeds with T. harzianum+P. fluorescens (5+6g/kg seeds) and P. fluorescens (6g/kg seeds) found effective in seeds pretreated with A. niger, while T. harzianum+P. fluorescens (5+6g/kg seeds) and P. fluorescens+B. subtilis (6+6g/kg seeds) found effective in seeds pretreated with Colletotrichum sp. and P. fluorescens+B. subtilis (6+6g/kg seeds) and T. viride+P. fluorescens (5+6g/kg seeds) found effective in seeds pretreated with Fusarium sp. However, overall results indicated that seed treatment with P. fluorescens+B. subtilis @ 6g + 6g/kg seeds and T. harzianum+P. fluorescens @ 5g + 6g/kg seeds proved very effective with higher seed germination, seedling length and vigour index in all pretreated seed mycoflora i.e, A. niger. Colletotrichum sp. and Fusarium sp.

Biosurfactant producing multifarious Streptomyces puniceus RHPR9 of Coscinium fenestratum rhizosphere promotes plant growth in chilli.

The present study involves isolation of Streptomyces spp. from rhizosphere of Coscinium fenestratum Gaertn, an endangered medicinal plant from Western Ghats of Karnataka, India. Four potential isolates were identified by 16S rRNA sequencing as Streptomyces sp. RHPR3, Streptomyces puniceus RHPR9, Streptomyces sp. RHPR14 and Streptomyces mediolani RHPR25. An enrichment culture method was used for the isolation of Streptomyces spp. for biosurfactant activity. Among four potential Streptomyces spp., S. puniceus RHPR9 showed highest Emulsification index (EI) (78±0.2%) and Emulsification assay (EA) (223±0.2 EU mL-1). Thin layer chromatography, Fourier transform infrared spectroscopy (FTIR) and mass spectrometric analysis revealed that as glycolipid. Further confirmed by presence of fatty acids like hexanoic acid methyl ester, decanoic acid by Gas chromatography mass spectroscopy (GC-MS) analysis. S. puniceus RHPR9 showed a significant IAA production (41μg mL-1), solubilized P (749.1 μg mL-1), growth promotion of chilli (Capsicum annuum L.) was evaluated using paper towel method and greenhouse conditions. S. puniceus RHPR9 showed a significant increase in seed vigor index (2047) and increase in plant biomass (65%) when compared to uninoculated control. To our knowledge, this is the first report on epiphytic S. puniceus RHPR9 isolated from an endangered medicinal plant C. fenestratum Gaertn, for biosurfactant production and plant growth promotion activities.

Effect of plant growth-promoting rhizobacterial treatment on growth and physiological characteristics of Triticum aestivum L. under salt stress

Salinity stress is a serious abiotic stress that affects crop quality and production. Rhizospheric microbes have immense potential in synthesizing and releasing various compounds that regulate plant growth and soil physicochemical properties. The aim of the present study was to evaluate the efficacy of indole-3-acetic acid (IAA)-producing rhizobacteria as biofertilizers under salt stress. Among the isolated strains from various soil samples, Bacillus megaterium strain PN89 with multifarious plant growth-promoting traits was selected and used as a monoculture and co-culture with two other standard strains. The plant promoting activity was evaluated using the paper towel method and pot test to observe the effects on the early stage and vegetative growth of wheat (Triticum aestivum L.). The treatment using PGPR strain presented noticeable but varying effects on plant growth under salt stress, that is, PGPR treatment often displayed a significant increase in germination percentage, root and shoot length, and other growth parameters of wheat compared to those in the non-inoculated control. Thus, these results suggest that B. megaterium PN89 can be applied as a bio-fertilizer to alleviate salt stress in T. aestivum.

Comparative study of microbial inoculants of cultivated and virgin soils of Nilgiri Biosphere for plant growth promotion

In virgin soils, microorganisms and plants live in harmony and both are dependent on each other for their livelihood. Absence of cultivation practices, undisturbed soil condition, high organic matter condition and other favourable conditions enables to flourish beneficial microbes. The research work was started to identify beneficial microbes from undisturbed virgin soils of Nilgiri biosphere with the ability to grow under low pH and under low temeperature conditions. Bio-inoculants viz., Azospirillum, Phosphobacteria, Azotobacter, Rhizobium and pseudomonas were obtained from cultivated and virgin soil samples of Nilgiris biosphere. When compared with type cultures, virgin soil isolates of respective inoculants have recorded better results in promoting plant dry weight in paper towel method. In cross streak assay, selected isolates found to be compatible with each other. In lignite carrier base formulation, the inoculants have reached a maximum population level of 107 and phosphobacteria reached 108 level. The population remained steady at this level up to 3 months. In the field trial studies conducted, the treatment of Azospirillum + Azotobacter + Phosphobacteria + Pseudomonas + 75% RDF has recorded maximum population of all the inoculants at 45th day after sowing. However, the maximum yield was observed in 100% RDF and bio-inoculant consortium applied treatment. This was closely followed by 75% RDF and bio-inoculant consortium applied plots. The results of the field trial have shown that bio-inoculant consortium along with 75% RDF application will lead to maximum yield with 25% saving in chemical fertilizer application.

Molecular mapping of dry root rot resistance genes in chickpea (Cicer arietinum L.)

Dry root rot (DRR) caused by Rhizoctonia bataticola [(Taub.) Butler] is an emerging disease of chickpea (Cicer arietinum L.) and a serious constraint to chickpea production in warm and arid regions. To identify the genomic regions conferring resistance to DRR, a total of 182 F9 derived Recombinant Inbred Lines (RILs) were developed from the cross between a susceptible line BG 212 and moderately resistant breeding line ICCV 08305. The parental lines and RILs were screened against Rb 6 isolate of R. bataticola using paper towel method under controlled environment at ICRISAT during 2016 and 2017. The RILs were genotyped with cost-effective SNP genotyping platform, Affymetrix® Axiom®CicerSNP array. As a result, a high-density genetic map with 13,110 SNP markers spanning 1224.11 cM with an average inter marker distance of 0.09 cM was developed. A single minor QTL (‘qDRR-8’) explaining 6.70% PVE with LOD scores 3.34 was identified on CaLG08 for DRR resistance which could be further explored for mining candidate genes and the linked SNP markers could be further validated for application in marker-assisted selection of DRR resistance in chickpea breeding programs.

Identification of new sources of resistance to dry root rot caused by Macrophomina phaseolina isolates from India and Myanmar in a mungbean mini-core collection

Dry root rot (DRR), caused by Macrophomina phaseolina, is a prevalent disease of mungbean in Myanmar, and an emerging problem in South Asia. The pathogen is a polyphagous necrotroph, survives in the soil for many years that results disease mitigation difficult. Managing DRR in mungbean through an integrated approach has been suggested, and the use of resistant varieties is one of the economical methods. The present study aimed to identify sources of resistance against DRR from a mungbean mini-core collection and to characterize the associated M. phaseolina isolates from India and Myanmar. Evaluation of the 296 mungbean mini-core accessions against the isolate MP1 by paper towel method identified 29 accessions with DRR resistance (disease scores: ≤ 3), and 18 of them with the consistent resistance in the repeated experiment. During the screening of 18 resistant accessions in the glasshouse, nine accessions were found DRR resistance in repeated sick pot experiments with ≤10% disease incidence. A subset of 30 accessions was selected from the mini-core collection based on their in vitro DRR reactions. These accessions were evaluated for DRR resistance in the field in Yezin, Myanmar in 2018 and 2019. Out of the 30 accessions, ten accessions were found DRR resistance with ≤10% disease incidence in both years of evaluations. Pooled analysis of percent disease incidence data of 15 accessions common in both glasshouse and field revealed the stability of accessions VI001509AG, VI001244AG, and VI001400AG for DRR resistance across years and locations. The three resistant accessions along with a susceptible check VC693088 were re-evaluated by paper towel method against nine additional M. phaseolina isolates from India (MP3-MP11). The accessions VI001509AG and VI001400AG were resistant to all nine isolates, while accession VI001244AG was resistant to MP5, MP6, and MP7 isolates. These accessions could be used in mungbean DRR resistance breeding programs.