Thumbnail Image

Acharya N G Ranga Agricultural University, Guntur

The Andhra Pradesh Agricultural University (APAU) was established on 12th June 1964 at Hyderabad. The University was formally inaugurated on 20th March 1965 by Late Shri. Lal Bahadur Shastri, the then Hon`ble Prime Minister of India. Another significant milestone was the inauguration of the building programme of the university by Late Smt. Indira Gandhi,the then Hon`ble Prime Minister of India on 23rd June 1966. The University was renamed as Acharya N. G. Ranga Agricultural University on 7th November 1996 in honour and memory of an outstanding parliamentarian Acharya Nayukulu Gogineni Ranga, who rendered remarkable selfless service for the cause of farmers and is regarded as an outstanding educationist, kisan leader and freedom fighter. HISTORICAL MILESTONE Acharya N. G. Ranga Agricultural University (ANGRAU) was established under the name of Andhra Pradesh Agricultural University (APAU) on the 12th of June 1964 through the APAU Act 1963. Later, it was renamed as Acharya N. G. Ranga Agricultural University on the 7th of November, 1996 in honour and memory of the noted Parliamentarian and Kisan Leader, Acharya N. G. Ranga. At the verge of completion of Golden Jubilee Year of the ANGRAU, it has given birth to a new State Agricultural University namely Prof. Jayashankar Telangana State Agricultural University with the bifurcation of the state of Andhra Pradesh as per the Andhra Pradesh Reorganization Act 2014. The ANGRAU at LAM, Guntur is serving the students and the farmers of 13 districts of new State of Andhra Pradesh with renewed interest and dedication. Genesis of ANGRAU in service of the farmers 1926: The Royal Commission emphasized the need for a strong research base for agricultural development in the country... 1949: The Radhakrishnan Commission (1949) on University Education led to the establishment of Rural Universities for the overall development of agriculture and rural life in the country... 1955: First Joint Indo-American Team studied the status and future needs of agricultural education in the country... 1960: Second Joint Indo-American Team (1960) headed by Dr. M. S. Randhawa, the then Vice-President of Indian Council of Agricultural Research recommended specifically the establishment of Farm Universities and spelt out the basic objectives of these Universities as Institutional Autonomy, inclusion of Agriculture, Veterinary / Animal Husbandry and Home Science, Integration of Teaching, Research and Extension... 1963: The Andhra Pradesh Agricultural University (APAU) Act enacted... June 12th 1964: Andhra Pradesh Agricultural University (APAU) was established at Hyderabad with Shri. O. Pulla Reddi, I.C.S. (Retired) was the first founder Vice-Chancellor of the University... June 1964: Re-affilitation of Colleges of Agriculture and Veterinary Science, Hyderabad (estt. in 1961, affiliated to Osmania University), Agricultural College, Bapatla (estt. in 1945, affiliated to Andhra University), Sri Venkateswara Agricultural College, Tirupati and Andhra Veterinary College, Tirupati (estt. in 1961, affiliated to Sri Venkateswara University)... 20th March 1965: Formal inauguration of APAU by Late Shri. Lal Bahadur Shastri, the then Hon`ble Prime Minister of India... 1964-66: The report of the Second National Education Commission headed by Dr. D.S. Kothari, Chairman of the University Grants Commission stressed the need for establishing at least one Agricultural University in each Indian State... 23, June 1966: Inauguration of the Administrative building of the university by Late Smt. Indira Gandhi, the then Hon`ble Prime Minister of India... July, 1966: Transfer of 41 Agricultural Research Stations, functioning under the Department of Agriculture... May, 1967: Transfer of Four Research Stations of the Animal Husbandry Department... 7th November 1996: Renaming of University as Acharya N. G. Ranga Agricultural University in honour and memory of an outstanding parliamentarian Acharya Nayukulu Gogineni Ranga... 15th July 2005: Establishment of Sri Venkateswara Veterinary University (SVVU) bifurcating ANGRAU by Act 18 of 2005... 26th June 2007: Establishment of Andhra Pradesh Horticultural University (APHU) bifurcating ANGRAU by the Act 30 of 2007... 2nd June 2014 As per the Andhra Pradesh Reorganization Act 2014, ANGRAU is now... serving the students and the farmers of 13 districts of new State of Andhra Pradesh with renewed interest and dedication...

News

https://angrau.ac.in/ANGRU/Library_Resources.aspx

Browse

2014 - 2019572020 - 202427
Reset filters
Subject: Plant Pathology × Start date: 2000 × Thesis Type: M.Sc ×
Reset filters

Search Results

Now showing 1 - 9 of 84
  • Thumbnail Image
    ThesisItemOpen Access
    “IN VITRO EVALUATION AND CHARACTERIZATION OF BIOCONTROL AGENTS ISOLATED FROM DIFFERENT AGRO-CLIMATIC ZONES OF ANDHRA PRADESH AGAINST MAJOR SOIL-BORNE PATHOGENS viz., Rhizoctonia solani, Sclerotium oryzae AND Fusarium oxysporum f.sp. ciceri ”
    (Acharya N G Ranga Agricultural University, 2024-05-06) MALIKIREDDY SWATHI; Dr. M.K. JYOSTHNA
    The present investigation was carried out to evaluate and to characterize the biocontrol agents isolated from different agro-climatic zones of Andhra Pradesh against major soil-borne pathogens viz., Rhizoctonia solani, Sclerotium oryzae and Fusarium oxysporum f.sp. ciceri. Infected plant samples of rice and chickpea were collected from the fields of RARS, Nandyal. Three pathogens viz., Rhizoctonia solani, Sclerotium oryzae and Fusarium oxysporum f.sp. ciceri were isolated from the diseased samples and proved the pathogenicity. Twenty Trichoderma isolates showing high antagonistic activity were collected from different Research stations of ANGRAU, Andhra Pradesh and pure cultures of Trichoderma isolates were maintained in PDA slants. All the twenty Trichoderma isolates were designated based on the location and were evaluated against the three pathogens in vitro. Twenty Trichoderma isolates were tested against R. solani in vitro. The maximum inhibition per cent which was from 72.33 per cent to 33.67 per cent. AT-6 Trichoderma isolate collected from Anakapalli Research station showed highest inhibition of 72.33 per cent followed by AT-1 (67.33%), AT-4 (66.33%) and AT-2 (65.67%) which were statistically on par with each other. The least inhibition was observed with AT-5 isolate with 33.67 per cent. Based on the results from this assay against R. solani, Trichoderma isolates viz., AT-6, AT-1, AT-4, AT-2 were carried forward to test the mechanism of antagonistic activity and their characterization. When twenty Trichoderma isolates were tested against Sclerotium oryzae, the maximum inhibition per cent was from 82.20 per cent to 44.40 per cent. AT-4 isolate showed maximum growth inhibition of Sclerotium oryzae (82.20%) followed by KT-1 (78.86%), AT-6 (77.76%) and AT-1(76.63%) which were on xvii par with each other. The least inhibition was observed in NT-7 isolate (44.40%). Based on the above results, Trichoderma isolates viz., AT-4, KT-1, AT-6 and AT-1 were carried forward to test the mechanism of antagonistic activity and their characterization. When twenty Trichoderma isolates were tested for their antagonistic potential against Fusarium oxysporum f.sp. ciceri, the maximum inhibition per cent was from 60.17 to 33.33 per cent. Maximum per cent inhibition of 60.17% per cent was observed with AT-6 isolate, followed by AT-2 (57.57%) and AT-1 (53.70%). Least per cent of inhibition was observed with AT-5 (33.33). Of the twenty Trichoderma isolates were tested against three pathogens, five Trichoderma isolates viz., KT-1, AT-1, AT-2, AT-4, AT-6 were selected based on their performance in dual culture assay and carried forward to test the antagonistic activity and their characterization. Maximum mycelial growth inhibition of R. solani, S. oryzae, Fusarium oxysporum f.sp. ciceri was due to production of volatile compounds by AT-6, AT-4, AT-6 Trichoderma isolates respectively. The effect of non-volatile compounds produced by potential Trichoderma isolates against R. solani was similar in all the three concentrations viz., 50, 30 and 10 per cent with the highest mycelial growth inhibition of R. solani by AT-6, S. oryzae by AT-4, Fusarium oxysporum f.sp. ciceri by AT-6 isolates respectively. Morphological characters of all five potential Trichoderma isolates viz., KT-1, AT-1, AT-2, AT-4, AT-6 like branching of conidiophores, shape and size of phialides and conidia were studied. KT-1 and AT-2 showed Sigmoid or hooked phialide shape and the size ranged in between 4.5-12.5 × 2.5-3.5 µm, conidia were globose to ovoid and size between 3.6-4.8 × 3.5-4 µm. AT-1 isolate showed ampulliform to lageniform phialides shape and size between 4.7–7.9 × 2.3–3.5 µm, conidia were subglobose to ovoid and the size was between 2.5–3.2 × 2.2–2.8 µm. AT-4 and AT-6 isolates showed bottle shaped phialides and the size ranged in between 6–11.5 × 2.5–2.9µm, conidia were ellipsoidal, subglobose shaped and size ranged between 4–6 × 3.0–4.0 µm. Tests for hydrolytic enzyme production viz., cellulases, proteases, amylases were performed. Of the five potential Trichoderma isolates KT-1, AT-4, AT-6 were positive for cellulase, AT-1, AT-4 and AT-6 isolates were positive for amylase and KT-1 isolate was found positive and the remaining isolates were found negative for protease production. AT-4, AT-6, KT-1, AT-2 isolates were positive for ammonia production. AT-1, AT-4, AT-6 isolates were positive for HCN production. All the five isolates produced siderophores. Molecular characterization of potential Trichoderma isolates viz., KT-1, AT-1, AT-2, AT-4, AT-6 was done by using ITS-1 and ITS-4 primers. Amplification of the 18S rDNA region from Trichoderma isolates with primers ITS 1 and ITS 4 yielded products of approximately 600 bp. BLAST analysis (BLAST) results showed that KT-1 and AT-2 isolates showed more per cent identity with T. viride, AT-1 with T. harzianum and AT-4, AT-6 with T. longibrachiatum
  • Thumbnail Image
    ThesisItemOpen Access
    MOLECULAR CHARACTERIZATION OF VIRUS ASSOCIATED WITH YELLOW MOSAIC DISEASE IN HORSE GRAM
    (Acharya N G Ranga Agricultural University, 2024-05-06) BODELA SUSHMA; Dr. PRADEEP MANYAM
    In this study, begomovirus associated with YMD of horsegram in Andhra Pradesh was studied based on diseased samples collected from Anantapuramu, Chittoor and YSR Kadapa districts. Based on PCR amplification and sequencing analysis, it was confirmed that all five samples infected with HgYMV indicating its predominance in horse gram growing areas of AP. Whole genome was determined for all the five isolates using overlapping primers for amplification of DNA-A and DNA-B components of HgYMV. The size of DNA-A in five isolates ranged from 2733-2736 nucleotides whereas for DNA-B, it was found to be 2670-2726 nucleotides in length. Complete genome analysis and sequence identity of HgYMV DNA-A and DNA-B of five isolates shared maximum nucleotide identity ranged from 95.5-98.7% for DNA-A and 94-98.2% for DNA-B with other HgYMV infecting pulses from different places. Among DNA-A and DNA-B components shared more than 94% identity among themselves, thus provining five isolates of HgYMV belong to same variant of the HgYMV. The recombination analysis revealed that DNA-A and DNA-B of HgYMV under present study is a recombinant, which is a derivative of known virus. The sequence analysis of IR region of HgYMV DNA-A and HgYMV DNA-B yielded broad range of identity (50.8-98.8% and 27.4-98.7% respectively) with HgYMV infecting other legumes. The IR region of all five isolates contains conserved TATA box, Nanomer and Ori sites. Nucleotide analysis of six ORFs of HgYMV DNA-A component with other begomoviruses was attempted. ORFAV1 and ORFAV2 shared 95.3 to 100% and 81.8 to 100% identity respectively with compared HgYMVs different isolates of HgYMV. A high similarity was also observed for other ORFs AC1 (95.0-100%), AC2 (80.7-100%), AC3 (83.5-99.2%) and AC4 xviii (92.8-100%). When compared with other begomovirus the closest association was found for MYMIV (80.6-86.6%), MYMV (82.2-84.5%) for DNA-A and MYMIV (60.3-68.4%), MYMV (60.5-68.3%) for DNA-B and less similarity was observed for DoYMV, VbGMV and FbLCV. The nucleotide analysis of ORFs of DNA-B component showed that high similarity (94.1-100%) was observed for BV1than BC1 (77.8-100%) which indicates BC1 is a divergent (KDP and TPT isolates). Bemisia tabaci populations were collected from four districts of Andhra Pradesh (YSR, Anantapuramu, Chittoor, Nellore) for identification biotypes and genetic groups. The existence of two genetic groups was revealed based on partial mtCOI gene sequence analysis. KDP and NLR belong to Asia-II-1 genetic group. Asia-II-8 genetic group was 1st time reported in AP identified in ATP and TPT B. tabaci population. The association of secondary bacterial endosymbionts with Bemesia tabaci populations was studied using16S rRNA/23S rRNA gene sequences. Wolbachia, a s-endosymbiont was identified in all four isolates which belongs to super group B. Whereas the association of Cardinium and Arsenophonus was observed from Kadapa B. tabaci population. The phylogenetic analysis identified Cardinium connected to C2 subgroup and Arsenophonus to A2 subgroup. Rickettesia was absent in all B. tabaci populations. Thus, Asia -II-1 genetic group from KDP was found in association with Wolbachia, Cardinium and Arsenophonus, while Asia-II-8 genetic group associated with only Wolbachia. A total of 37 Horse gram genotypes were screened for identifying resistance against Horse gram yellow mosaic virus. The PDI values of 37 genotypes ranged from 0-97.2%. Eighteen genotypes were found resistant under natural disease screening methods. Eight genotypes exhibited higher degrees of susceptibility (30.85-97.2%). The apparent rate of infection which depicts disease progression indicated that slow progress in resistant type genotypes (BSP21-3, r:0.20), whereas faster rate of spread disease in susceptible genotypes Indira Kulthi (r:0.45) and BSP21-5 (r:0.454).
  • Thumbnail Image
    ThesisItemOpen Access
    MOLECULAR CHARACTERIZATION OF SESAME PHYLLODY PHYTOPLASMA AND ITS EPIDEMIOLOGY IN ANDHRA PRADESH
    (Acharya N G Ranga Agricultural University, 2024-05-06) SANDHYA GOPISETTY; Dr. M. GURIVI REDDY
    An investigation was carried out to identify and characterize the phytoplasma strains associated with the sesamum phyllody disease showing symptoms of phyllody, floral virescence and yellowing in Andhra Pradesh. A roving survey was conducted in Chittoor, Kadapa districts in kharif season and Chittoor, Kadapa, Vishakapatnam, Vizianagaram and Srikakulam districts of Andhra Pradesh in late rabi during 2021-22. The disease etiology was confirmed by performing nested PCR assays using universal primer pairs P1/P7 followed by R16F2n/R16R2, which amplified ~1.8 and ~1.25 kb product of 16S rRNA gene. The results of phytoplasma identification in the infected samples were further validated by using secA multilocus gene which yielded an expected amplicon sizes of ~840bp by utilizing primer pairs SecAfor1/SecArev3 BLAST and phylogenetic analysis of 16S rDNA and secA genes revealed that phytoplasma associated with sesame phyllody disease in kharif season belonged to Ca. Phytoplasma australasia (16SrII) group whereas in late rabi season it belonged to Ca. Phytoplasma asteris (16SrI) group. Virtual RFLP analysis was performed to further confirm phytoplasma at the subgroup level which classified the kharif isolates under the 16SrII-D subgroup and late rabi isolates under the 16SrI-B subgroup. Symptomatic weeds, other host plants and insect vectors feeding on infected sesame plants were collected from in and around infected sesame fields. Out of them four weed species: Parthenium hysterophorus, Celosia argentea, Cleome viscosa, Tephrosia purpurea; two other host plants, sun hemp (Crotalaria juncea), redgram (Cajanus cajan) were tested positive for phytoplasma utilizing similar set of primer pairs of 16S rRNA and secA xix genes. Hishimonus phycitis collected from infected sesame fields of Chittoor district also tested positive for Ca. Phytoplasma australasia 16SrII-D subgroup phytoplasma which was identified as a potential putative vector for the sesame phyllody phytoplasma. The effects of sowing dates, vector population and weather parameters on sesame phyllody disease incidence were studied during kharif and late rabi seasons. The lowest disease incidence of 62% was observed in August sown crops and the highest disease incidence of 81.87% was observed in June sown crops in kharif season. During late rabi season less or negligible per cent of disease incidence was observed compared to kharif season. The vector population and all the weather parameters except rainfall were significantly correlated with disease incidence on all sowing dates
  • Thumbnail Image
    ThesisItemOpen Access
    CHARACTERIZATION OF BANDED LEAF AND SHEATH BLIGHT PATHOGEN AND ITS MANAGEMENT IN BARNYARD MILLET
    (Acharya N G Ranga Agricultural University, 2024-05-06) PALLAVI TATINENI; Dr. T. S. S. K. PATRO
    In the present investigation on “Characterization of banded leaf and sheath blight pathogen and its management in barnyard millet”, the banded leaf and sheath blight (BLSB) affected leaf samples were collected from different millet growing regions of India and the pathogen was isolated. Initially, seven different media were used to study their effects on morpho-cultural characteristics of the pathogen among which Potato Dextrose Agar (PDA) was found to support best radial growth of the pathogen in addition to production of highest number of sclerotial bodies and hence was used to carry out further morpho-cultural characterization studies for all the isolates. Morpho-cultural characterization studies revealed that, there was considerable variation among the isolates in various morpho-cultural characters like radial growth, colony colour, colony texture, hyphal width, sclerotia size, sclerotia weight, distribution of sclerotia, pattern of arrangement of sclerotia, sclerotia texture and sclerotia colour. Molecular characterization using ITS1/ITS4 primers revealed that all the isolates belong to AG1-IA group of Rhizoctonia solani and there was no much variability among the isolates collected from different geographical locations which depicts the genetic flexibility and adaptability of the pathogen to spread to new ecological niches. Pathogenic variability was studied for all the 10 isolates and the incubation period varied from 4 to 8 days. The isolate, RAP-2 was more virulent. Correlation analysis between different morpho-cultural characters and virulence of the isolates revealed that isolates with higher radial growth were more virulent and also there exists a significant positive correlation between sclerotia size and sclerotia number, hyphal width. Yield loss assessment studies revealed that the potential yield loss caused by the pathogen ranged from 54% to 62%. Integrated management studies include screening for host resistance, evaluation of different treatments viz., chemicals viz., propiconazole @ 0.1%, tebuconazole + trifloxystrobin @ 0.05%, biocontrol agents viz., Trichoderma asperellum, Pseudomonas xvii fluorescens, Bacillus subtilis, biorational viz., panchagavya against banded leaf and sheath blight disease. The study identified the genotypes, VBBC-340, VB 19-3, VB-19-4, as resistant and seed treatment and foliar spray with tebuconazole + trifloxystrobin @ 0.05% as the most effective among the treatments tested.
  • Thumbnail Image
    ThesisItemOpen Access
    STUDIES ON BIOLOGICAL CONTROL POTENTIAL OF NATIVE BACILLUS SPP. AGAINST RHIZOCTONIA SOLANI KUHN. CAUSING RICE SHEATH BLIGHT
    (Acharya N G Ranga Agricultural University, 2024-05-06) PAGIDIRAI KALAVATHI; Dr. M.K. JYOSTHNA
    A roving survey was conducted during, rabi, 2020-2021 in Chittoor and Nellore districts of Andhra Pradesh to assess the disease severity of sheath blight disease in rice. The disease severity ranged from 6.11 to 13.44%. Rice sheath blight pathogen R. solani was isolated from the diseased samples obtained during survey. Its pathogenicity was proved by using mycelial ball insertion technique. A total of 26 native Bacillus spp were isolated from the rhizoplane soils of rice crop of Chittoor and Nellore districts and their antagonistic efficiency was tested using dual culture technique. Among the isolates, NB13 showed maximum antifungal efficiency with 86.15% followed by CB10 (81.60%) and CB4 (75 %). Maximum inhibition of sclerotial germination was observed in CB4 (98.42%) followed by NB13 (97.2%) and CB10 (96.36%) and maximum per cent of lysis of sclerotia was observed in CB10 isolate (100%) followed by CB4 (98.14%) and NB13 (95.55%). Those isolates CB4, CB10, NB13 recorded maximum mycelial inhibition, sclerotial inhibition and sclerotia lysis which are significantly on par. Cultural characters viz., colony shape, colour, size, surface, margin, elevation and time of colony appearance of the potential Bacillus isolates were recorded. Among all isolates NB4, NB13, CB10 isolates produced irregular, white, large colonies with rough surface, lobate margins, flat elevation and formed colonies with 48h after inoculation. CB4 produced irregular, white, large colonies with rough surface, filamentous margins and formed colonies with 48h after inoculation. Out of ten potential isolates tested for biochemical tests, all isolates showed positive reaction to gram staining, endospore staining, motility test and catalase test, whereas only seven isolates showed positive reaction to anaerobic growth, six isolates showed positive reaction to oxidase test and three isolates showed positive reaction to nitrate reduction test. xvi 16S r DNA sequence analysis revealed that the NB4, NB13, CB4 and CB10 have close similarity with Bacillus subtilis. Out of the 10 potential isolates maximum chitinase activity (maximum halo zone diameter (2.6 cm) and chitinolytic index (3.13) and oxalate oxidase enzyme activity (maximum halo zone diameter 2.35cm) was observed in isolate CB10. A total of ten potential isolates were screened for PGPR characteristics. All the isolates were positive to siderophore production, phosphate solubilization activity, of which CB10 isolate recorded highest siderophore index, maximum zinc carbonate solubilization index and efficiency and NB13 recorded maximum IAA production, PSI and PSE% and also produced maximum ZSI and ZSE % for zinc phosphate, CB4 recorded highest potassium solubilizing index and efficiency and five isolates were positive for HCN production, four isolates for organic acid production, while isolate CB10 was produced maximum ACC (58nm-α-ketobutyrate mg-1h -1 ). All the ten potential isolates significantly increased seed germination, seedling growth (root &shoot length) and vigor index of rice seedlings when compared to control by paper towel method. Among these highest vigor index was recorded NB13 (2683.66), followed by CB10 (2380.70), CB4 (2214.83) which are significantly on par.
  • Thumbnail Image
    ThesisItemOpen Access
    In vitro evaluation and characterization of biocontrol agents isolated from different Agro climatic zones of Andhra Pradesh against major soil-borne pathogens of groundnut
    (Acharya N G Ranga Agricultural University, 2024-05-01) N. DIVYA; Dr. K. VEMANA
    Soil borne pathogenic fungi are of major concern in agriculture which significantly reduce the plant yield. Management through chemicals imposes environmental threats potentially dangerous to both humans as well as to animals. The present study's main goal was to identify and assess efficient Trichoderma spp. for biocontrol of the principal groundnut soil-borne diseases Aspergillus niger, Rhizoctonia bataticola, and Sclerotium rolfsii. The investigation of morphology, bio-efficacy, and biochemical synthesis (enzymes and antifungal chemicals) is crucial to agents (BCAs) select high potential bio control against complex plant pathogens and to confirm the mycoparasitic antagonistic capacity of Trichoderma. In the current study twenty isolates were evaluated against soil borne pathogens. In dual culture the interactions of Trichoderma isolate with s.rolfsii observations on fourth day of incubation showed that among different isolates tested Trichoderma isolate KT-3 recorded significantly high per cent of inhibition (76.67%) and least mycelial growth of S.rolfsii (2.10cm). Observations on sixth day of incubation revealed that, Trichoderma isolate NT-3 (80.37%) showed highest per cent of inhibition and lowest mycelial growth of A.niger (1.77cm) and appeared to be significantly superior among the 20 isolates followed by Trichoderma isolate- KT-1 (78.15%) and AT-1(76.30%) against A.niger. Against R. bataticola observations on sixth day of incubation revealed that the inhibition per cent ranged from (75.56% - 52.96%) Trichoderma isolate AT-6 showed least mycelial growth (2.33cm) and maximum inhibition (75.56%) of growth of R. bataticola. Selection of potential isolates of Trichoderma spp. against soil-borne pathogens, is done based on per cent inhibition (Bell’s scale method). Among the 20 isolates tested it appeared that five isolates of Trichoderma xiv spp. (AT-1, AT-6, NT-3, KT-1 and KT-3) were showing highest per cent inhibition against three pathogens on an average and falling under the category of Group 2. Selected isolates were further evaluated to test screen their lytic enzyme ability, volatile and non-volatile efficacy. Among five Trichoderma isolates tested for the antifungal volatile metabolites production against the pathogens, isolate KT-3 showed high per cent of inhibition (49.63%) and least mycelial growth of S. rolfsii (4.53cm) and differed significantly with other Trichoderma isolate against S. rolfsii. Isolate NT-3 was recorded maximum growth inhibition (80.00%) least mycelial growth of A. niger (1.80cm) and found significantly superior over Trichoderma isolate KT-1 (76.3%), AT-1 (72.22%), AT-6(68.89%) and KT-3(62.59%). Isolate AT-6 showed significantly higher per cent of inhibition (59.62%) and least mycelial growth of R. bataticola (3.67cm) followed by Trichoderma isolate KT-1 (49.26%) and Trichoderma isolate NT-3(40.00%). When cultrate filtrate of Trichoderma isolates tested at different concentrations viz., 10, 30 and 50 per cent concentrations, at 50% concentration highest rate of inhibition was noticed. Among the five isolates at 50 per cent concentrations against S. rolfsii Trichoderma isolate KT-3(78.89%) showed highest per cent of inhibition followed by AT-1(76.67%). On the sixth day maximum inhibition against A. niger was noted on NT-3(85.56%) followed by Trichoderma isolate KT-1(84.81%) which are on par with each other. The least inhibition was observed in the isolate KT-3(75.56%). Against R. bataticola, Trichoderma isolate AT-6 (74.44%) showed highest inhibition followed by Trichoderma isolate KT-3 (73.33%) which are at par with above isolate. Trichoderma isolate were grouped based on the morphological characters likes sporulation type, shape and size of conidia, branching pattern, phialides length AT 1 and KT-3 recognized as T. harzianum, KT-1 as T. viride, NT-3 as T. asperllum, and AT-6 as T.longibrachiatum. When biochemical characterization of five potential isolates were screened, Trichoderma isolate AT-6, NT-3 and KT-1 showed positive results for cellulase test. Isolates KT-1 showed positive for protease test. For amylase test KT-3, NT-3 and AT-1 showed positive with halo zone formation and for siderophore assay all the isolates showed positive results and for HCN assay the Trichoderma isolate KT-1, AT-6 and NT-3 showed positive results. For NH3 assay KT-1, NT-3, AT-6 and KT-3 showed positive. The potential Trichoderma spp. were identified at molecular level using ITS 1 and ITS 4 primers and based on the per cent similarity from the NCBI data base showed that out of five isolates two isolates Trichoderma isolates-AT-1 and KT-3 were identified as Trichoderma harzianum and Trichoderma isolate-AT-6 as Trichoderma longibrachiatum, NT-3 as Trichoderma asperellum and KT-1 as Trichoderma asperellum (Trichoderma viride).
  • Thumbnail Image
    ThesisItemOpen Access
    STUDIES ON IDENTIFICATION, CHARACTERIZATION AND EFFECTIVENESS OF Trichoderma spp. AGAINST CHICKPEA SOIL BORNE PATHOGENIC FUNGI
    (Acharya N G Ranga Agricultural University, 2023-12-26) MADDI SANDHYA; S. KHAYUM AHAMMED
    In the present investigation on “Studies on identification, characterization and effectiveness of Trichoderma spp. against chickpea soil borne pathogenic fungi”, three soil borne pathogenic fungi i.e., Sclerotium rolfsii, Rhizoctonia bataticola and Fusarium oxysporum f. sp. ciceri symptoms were collected from the infected fields of chickpea and were isolated. Thirteen Trichoderma isolates were collected from the Department of Plant Pathology, Agricultural College, Bapatla. Of all the 13 Trichoderma isolates, four isolates were considered as potential isolates and further assessment was made to study their variability in morphological, cultural, biochemical and molecular characters. They were also tested for their sensitivity towards various fungicides and insecticides. Variability studies of thirteen Trichoderma isolates collected were performed using cultural characters such as colony texture, elevation, growth habit, colony margin and mycelial nature. All Trichoderma isolates were grown on PDA to study their morphological and cultural variability and grouped into four categories i.e., very fast, fast, medium and slow based on radial growth. Isolate T 19002 showed fast growth (4.1-6.0 cm) and remaining 12 isolates with medium growth of 2.1 to 4.0 cm range at 1 day after incubation (DAI). At 3 DAI, T 19001 and citrus isolates showed fast growth and remaining 11 isolates showed very fast growth (>6.1 cm) and considered to be having better proliferation and all isolates showed very fast growth by 5 DAI. Observations at 3 DAI indicated that most of the isolates recorded growth rate between 0.5 to 1.0 mm/hr. xvii Based on bioefficacy studies in vitro using dual culture technique against S. rolfsii, R. bataticola and Foc. The present investigation revealed that incubation up to five days was insufficient to categorize an isolate as potential. Hence, based on other qualitative parameters such as zone of inhibition, overgrowth potential, lysis, sporulation in Trichoderma were also considered for screening and selection of potential isolates. Isolates (T 19006, T 19015, T 19002, T 19026) with fast growth, lysing and overgrowing with good sporulation over test pathogen at zone of inhibition (zi), pigmentation were considered as potential isolates against all three test pathogens i.e., S. rolfsii, R. bataticola, Foc and used for further studies. The four potential Trichoderma isolates were assessed for their variabililty in morphological, cultural, biochemical, molecular characterization and their sensitivity in radial growth and spore germination. Based on morphology of conidiophore branching, phialides shapes, the 4 Trichoderma isolates were identified as T. harzianum (T 19006, T 19015), T. asperellum (T 19002), T. aureoviride (T 19026). The four potential Trichoderma isolates were assessed for their variabililty in morphological, cultural, biochemical, molecular characterization and their sensitivity in radial growth and spore germination. Based on morphology of conidiophore branching, phialides shapes, the 4 Trichoderma isolates were identified as T. harzianum (T 19006, T 19015), T. asperellum (T 19002), T. aureoviride (T 19026). Assessment of molecular variability using SSR primers for 4 potential Trichoderma isolates was performed which resulted in 60 bands with polymorphism having band size from 100 to 2000 bp. Where, some of the primer sequence was used to identify Trichoderma genus upto species level and confirmed them as T. asperellum, T. aureoviride and T. harzianum. Dendrogram obtained had 2 clusters (I and II). Cluster I consists of 3 isolates and cluster II contain I isolate (T19002), had a similarity of 53 per cent with each other cluster. Biochemical studies were performed to test their chitinase and β-1,3-glucanase activity, where banana isolate have high enzyme production i.e., 181.54 mg ml-1 and 122.06 μmol min-1 ml-1 respectively. Among six insecticides tested for their sensitivity by poison food technique, spinosad completely inhibited the radial growth of all four Trichoderma isolates at all the three concentrations (R/2, R and 2R respectively). Indoxacarb showed mycelial growth only at R/2 concentration and complete inhibition was observed both at R and 2R concentrations in all Trichoderma isolates. Among six fungicides tested for their sensitivity by using slide germination technique, metalaxyl + mancozeb, azoxystrobin + tebuconazole, carbendazim + mancozeb, azoxystrobin + difenconzole, carboxin + thiram complete inhibition of spore germination in four potential Trichoderma isolates at all the three concentrations (R/2, R and 2R) was observed and tebuconazole+trifloxystrobin showed spore germination with significant difference when compared to control. Among six insecticides tested for their sensitivity, spinosad completely inhibited the spore germination of all Trichoderma isolates followed by profenophos and rynaxypyr at all the three concentrations (R/2, R and 2R respectively).
  • Thumbnail Image
    ThesisItemOpen Access
    CHARACTERIZATION OF MUNGBEAN GENOTYPES WITH VARIABLE REACTIONS TO MUNGBEAN YELLOW MOSAIC VIRUS INFECTION
    (Acharya N G Ranga Agricultural University, 2023-12-26) CHALLA SRI PRIYA; G. BINDU MADHAVI
    The present investigation on “Characterization of mungbean genotypes with variable reactions to mungbean yellow mosaic virus infection” was carried out at the Regional Agricultural Research Station (RARS), Lam, Guntur, Andhra Pradesh during rabi 2021-22. Mungbean [Vigna radiata (L.) Wilczek] is an important short duration grain legume because of its low water requirement, and as a crop suitable for rotation and nutritional security being a rich dietary source of protein. Biotic stress produced by viruses especially mungbean yellow mosaic virus (MYMV) is the major constraint in its cultivation causing substantial yield losses. Total twenty five mungbean genotypes along with LGG 450 as susceptible check were screened against Mungbean yellow mosaic virus disease under field conditions. Symptoms of MYMV first appeared on young leaves in the form of yellow, diffused, round spots scattered on the leaf lamina. The infected leaves later turned necrotic. The diseased plants matured later and had relatively few flowers with shriveled pods. Disease symptoms first appeared in genotypes LGG 673, LGG 677, LGG 460 and LGG 450 by 20 DAS while in genotypes, LGG 610, LGG 604, LGG 606, LGG 625, LGG 645, IPM 2-14 and Pusa 9072 disease occurred at 60DAS. The data on incidence and severity of yellow mosaic virus was recorded at different intervals i.e., 20, 40 and 60 DAS. The per cent disease incidence of MYMV among 26 mungbean genotypes was varied from 4.25 to 51.76% and disease severity (PDI) ranged from 1.58 to 76.49 % during 60 DAS. Further, tested genotypes were grouped into different categories based on 0-9 disease scale given by AICRP and MULLaRP. Among the 26 genotypes of mungbean, seven were found resistant, 15 genotypes xv were moderately resistant, two were moderately susceptible, three genotypes were susceptible and the check LGG 450 showed highly susceptible reaction to yellow mosaic virus of mungbean. Morphological characters viz., trichome density, leaf thickness, stomatal frequency, leaf epicuticular wax content and leaf colour intensity were evaluated in all 26 mungbean genotypes during 40 and 60 DAS. It was observed that trichome density, leaf epicuticular wax content and leaf colour intensity in MYMV resistant mungbean genotypes were comparatively high to that of susceptible genotypes. Similarly, leaves of MYMV resistant mungbean genotypes were thicker when compared to susceptible genotypes and highly susceptible check. However, stomatal frequency was found maximum in susceptible genotypes than the resistant genotypes. The biochemical parameters viz., total sugars, reducing sugars, total phenols, total protein and total chlorophyll content were studied both at 40 and 60 DAS in all mungbean genotypes. Decreased total sugar content was observed in susceptible entries compared to resistant ones during both periods of observations i.e., 40 and 60 DAS.It was found that total reducing sugar content was maximum in MYMV resistant genotypes followed by moderately resistant genotypes and then susceptible genotypes. The similar trend was followed in total phenols, total proteins and total chlorophyll content in all tested mungbean genotypes. The molecular characterization of yellow mosaic virus (YMV) in infected mungbean genotypes was done by using the coat protein (CP) and movement protein (MP) gene specific primers from isolates collected at RARS, Lam farm to confirm their strain as MYMV or MYMIV.PCR based characterization of strains (MYMV/MYMIV) were carried out using their gene specific primers respectively.Distinct viral gene specific PCR products corresponding to CP ~648 bp, ~704 bp and ~920 bp were obtained for MYMV and MYMIV respectively. The movement protein gene sequence was also successfully amplified with a fragment size of 900 bp using MYMIV- MP gene specific primer.The samples were further confirmed by CP and MP gene sequencing.The obtained sequences were compared with the other selected begomovirus sequences from the NCBI blast database. The full length coat protein and movement protein gene sequences of MYMV and MYMIV isolates along with available corresponding DNA-A and DNA-B sequences of yellow mosaic virus (YMV‟s) infecting mungbean genotypes when subjected to phylogenetic analysis formed two major clusters. Results were found to show more sequence homology with MYMIV isolates from South India confirming that the begomovirus causing yellow mosaic disease in mungbean is explored to be as strain of MYMIV and not as MYMV.
  • Thumbnail Image
    ThesisItemOpen Access
    ISOLATION OF Pseudomonas fluorescens AND PINK PIGMENTED FACULTATIVE METHYLOTROPHS FOR MANAGEMENT OF URDBEAN FUNGAL FOLIAR DISEASES
    (Acharya N G Ranga Agricultural University, 2023-12-26) DASARI MANIKANTHA; V. MANOJ KUMAR
    A total of 40 isolates, 20 of Pseudomonas fluorescens and 20 methylotrophic bacteria were isolated from the blackgram phyllosphere and their biochemical studies revealed that all the P. fluorescens isolates tested to be positive for Catalase, Amylase, Urease and Protease activity. 17 out of 20 isolates had Siderophore production and only two isolates has HCN production. Only one isolate had shown positive for indole production. All the PPFM isolates were found positive for Catalase and Urease activity and negative for HCN production. Fourteen out of 20 PPFM isolates had shown Amylase activity, only one isolate shown positive for Protease activity and two had shown positive for Siderophore production. Testing for PGP traits revealed that 15 P. fluorescens isolates had shown Psolubilization, six isolate had shown IAA production and five isolates had shown Ksolubilization. Eleven PPFM isolates had shown positive for P- solubilization and only one isolate had shown positive fir IAA production and all the PPFM isolates had shown negative for K- solubilization. In vitro dual culture studies revealed that, among 20 P. fluorescens isolates tested, two isolates viz., CBP- 05 and PPP-01 were found to be the most promising isolates with maximum antagonistic potential against Corynespora cassiicola (66.51% and 64.99%) and Alternaria alternata (60.43% and 60.43%). Two methylotroph isolates viz., PPM-01 and ABM-04 exhibited maximum antagonistic potential against C. cassiicola (68.04% and 54.34%) and A. alternata (34.55% and 34.55%). xvii Intra and inter compatibility studies of four antagonistic bacterial isolates, viz., two Pseudomonas (CBP-05, PPP-01) and two methylotrophs (PPM-01 and ABM-04) revealed that all the isolates were compatible with each other under in vitro conditions which was tested through cross streak method. Based on 16S rRNA gene sequencing the Pseudomonas isolate PPP-01 and CBP-05 was found closely related with Pseudomonas fluorescens. However, the methylotroph PPM-01 grouped with Methylobacterium indicum and ABM-04 grouped with Hyphomicrobium facile. The pathogens Corynespora grouped with Corynespora cassiicola isolate while Alternaria was related with Alternaria alternata isolate. Under field conditions, Fungicidal check had shown lowest PDI and AUDPC against Corynespora leaf spot (28.11% and 501.10 respectively) and Powdery mildew (0.00% and 0.02 respectively) and there was a significant increase in yield (1130.40 kg ha-1), number of pods per plant (20.10), no. of seeds per pod (5.63) and test weight of 3.85g. Among the antagonist treated plots, foliar spray of consortium of CBP-05, PPP- 01, PPP-01 and ABM-04 @ 108 CFU ml-1 has recorded the lowest PDI against Corynespora leaf spot (36.37%) and Powdery mildew (38.17%) and minimum area under disease progress curve for both Corynespora leaf spot (639.03) and Powdery mildew (644.33). It was also observed to significantly increase the number of pods per plant (19.50), No. of seeds per pod (5.43) and the highest test weight of 3.77g, yield of 1080.25 kg ha-1. However, the benefit cost ratio (BCR) of the different treatments varied from 0.99 to 1.70 with the highest BC ratio was recorded with Treatment T7 (CBP-05, PPP- 01, PPP-01 and ABM-04 (FS)) (1.70) and the fungicide treatment having BC ratio of 1.55 which represents, the combination treatment is a potential alternative to fungicides