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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...

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    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).
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    ThesisItemOpen Access
    ETIOLOGY, EPIDEMIOLOGY AND MANAGEMENT OF CHRYSANTHEMUM FLOWER BLIGHT
    (Acharya N G Ranga Agricultural University, 2023-12-26) A. SNEHALATHA RANI; V. PRASANNA KUMARI
    The present investigation entitled “Etiology, epidemiology and management of chrysanthemum flower blight” was carried out to assess the prevalence of the disease and further characterization. Disease dynamics during 2019-21 revealed that it is an important emerging disease both under protected and open filed conditions of Andhra Pradesh. Maximum per cent disease incidence (48.40 %) and severity (28.28 %) was recorded in East Godavari followed by Chittoor and Visakhapatnam districts. Predominant pathogen was Ectophoma multirostrata along with occurrence of Stemphylium lycopersici, Botrytis cinerea, Alternaria alternata, Colletotrichum gloeosporoides and Lasiodiplodia theobroame. Pathogenicity of the six pathogens was proved on chrysanthemum cultivar New Man and twelve isolates of Ectophoma were characterized morphologically and molecularly. Ectophoma culture was greenish grey initially with floccose to felty appearance and later became dark brown or black with appressed texture on potato dextrose agar. It produced dark brown to black, globose or irregular, solitary or aggregated pycnidia that were partly or fully submerged in the media. Conidia were hyaline, single celled, mostly oblong to ellipsoid and guttulate. Pycnidial length and width of population varied between 89.67 and 132.98 μm and from 60.56 to 89.68 μm respectively. Mean conidial length of population was 4.00±0.24 μm and conidial width of population ranged between 1.00 and 2.90 μm. Pathological and morphological characters contributed significantly to study the divergence of isolates when compared to cultural characters. Incubation period (5.33 to 8.33 days) and lesion length (7.67 to 38.33 mm) among the isolates in detached xix leaf assay correlated with the incubation period and disease severity in pot experiment (1.00 to 2.67 days and 17.67 to 65.67 PDI respectively). Based on different characters studied, the multivariate analysis revealed grouping the twelve isolates in to four clusters. Simple sequence repeat (SSR) primer based diversity analysis showed that the Ectophoma isolates, VSPPM3 and VSPPM4 from Visakhapatnam were closely related with 96 per cent similarity whereas VSPPM3 from Visakhapatnam and EGPM3 from East Godavari were distantly related with only fifty per cent similarity. Isolates were grouped irrespective of their geographical region based on clustering by Tocher’s and SSR analysis. The most virulent isolate, EGPM1 was characterized molecularly by sequencing and Phylogenetic trees constructed based on ITS region and actin gene sequences showed 92 to 100 per cent similarity with Ectophoma multirostrata. The ITS sequence of EGPM1 (EGPM19-1) was submitted and obtained NCBI unique accession number, ON819852. Correlation studies between disease parameters of chrysanthemum and weather parameters during 2019-20 and 2020-21 revealed that disease incidence and severity were significantly and negatively correlated with maximum temperature, minimum temperature, morning relative humidity and evaporation during first and second dates of planting. In vitro fungicide assays were conducted with selected fungicides, against the six pathogens isolated where complete inhibition of E. multirostrata, B. cinerea, A. alternata and C. gloeosporoides was observed with difenoconazole while mancozeb completely inhibited S. lycopersici and L. theobromae. Under field conditions two years pooled data revealed that two sprays of difenoconazole @ 0.1 per cent was significantly superior over other treatments with 40.00, 76.67 % disease incidence, 2.17, 7.64 % of disease severity on flowers and 3.52, 4.28 % of disease severity on leaves respectively at five and 15 days after second spray. It was also observed with the highest yield (6.87 kg plot-1; 7.63 t ha-1), highest B: C ratio (2.06) and highest shelf life period of flowers (4.83 days, 10.33 days at room temperature and 4 0C respectively).
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    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.
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    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
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    ThesisItemOpen Access
    STUDIES ON DIVERSITY OF Rhizoctonia solani Kuhn INFECTING RICE IN GODAVARI ZONE OF ANDHRA PRADESH AND ITS MANAGEMENT
    (Acharya N G Ranga Agricultural University, 2023-12-26) VUNDAVALLI SWETHA BINDU; M. RAMABHADRA RAJU
    In the present study, on “Studies on diversity of Rhizoctonia solani Kuhn infecting rice in Godavari zone of Andhra Pradesh and its management” survey during kharif 2021 in ten villages from each district of West and East Godavari district. Survey revealed that the sheath blight disease severity was recorded highest in Maruteru (45%) and lowest in Seethanagaram (34%). Studies on cultural and morphological variability of twenty Rhizoctonia spp. isolates obtained from West and East Godavari districts of A.P. indicated that maximum radial growth was observed in WSB21-1 (9.00 cm) with high growth rate of (1.25 mm h-1). Colony colour varied from White (8/1 7.5YR), light brown (6/3 7.5YR), pale brown (6/3 10YR), brownish yellow (6/6 10YR), light yellowish brown (6/3 2.5Y). Six types of growth patterns were observed. Variation in sclerotia colour was observed viz., light brown, dark brown, brown and black brown. Different patterns of sclerotia were observed. Three different types of sclerotia distribution was observed i.e., aerial, surface and surface and aerial. Two types of sclerotia texture were observed i.e., rough and smooth. Time taken for sclerotial formation varied from three to seven days. Sclerotia number varied from 0 to 60. xiv Sclerotial width among isolates ranged from 1.56 to 2.63 mm (ESB21-3). Hyphal width varied from 3.82 (ESB21-4) to 14.68 μm (ESB21-3). Molecular variability was done for all twenty isolates by using ITS and Rhizoctonia specific primers. Among twenty isolates, twelve isolates amplified for Rs2.1 primer indicating that the isolates belong to AG2-1 and AG-8. One isolate was amplified using RoGr-1 primer indicating that isolate as R. oryzae. One isolate amplified by Rs8 primer indicating WSB21-2 belongs to AG-8. In vitro studies of fungicides revealed that Hexaconazole 5% SC, Thifluzamide 24% SC and Carbendazim 50%WP were found superior in inhibiting the R. solani at all concentrations i.e., upto R/5 (200 ppm). In vitro studies of organic extracts revealed that vitex leaf extract was effective against both mycelial growth and sclerotial production of R. solani, whereas, Dried ginger buttermilk extract was effective against only on sclerotial production of R. solani, however, Cow dung + Urine + Asafoetida was found effective against only on mycelial growth of R. solani. Jeevamrutham was found effective at lower concentrations viz., R/4 (2500 ppm) and R/5 (2000 ppm), whereas Bael leaf extract was found siginificantly superior upto R/2 (5000 ppm) in case of filter sterilized extracts on mycelial growth of R. solani. Pot culture studies of fungicides revealed that azoxystrobin 11%+ tebuconazole 18.3% found effective against sheath blight followed by thifluzamide 24% SC and hexaconazole 5% SC. Among the organic extracts, Sour buttermilk followed by Beejamruth, Cow dung + Urine + Asafoetida whereas, treated check carbendazim 75% WP also found effective with highest per cent inhibition.
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    ThesisItemOpen Access
    VARIABILITY IN RICE BLAST PATHOGEN (Pyricularia oryzae B.C. Couch) AND MOLECULAR PROFILING OF BLAST RESISTANCE GENES IN RICE GENOTYPES
    (Acharya N G Ranga Agricultural University, 2023-12-26) NARRA NEERAJA; V. Bhuvaneswari
    The present investigation was undertaken with an aim to know the variability between leaf blast and neck blast pathogen populations. Studies carried out on the variability of isolates using morphological and molecular characteristics. In another study efforts were made to identify the blast resistance genes in rice genotypes. Survey was conducted during rabi, 2021-22 in five different mandals of West Godavari district of Andhra Pradesh for the collection of blast diseased samples and to assess the severity of the disease. The highest mean leaf blast Per cent Disease Index (PDI) 38.48% was recorded in Bhimadolu mandal and the lowest was recorded in Palakollu mandal (18.31%). Among the five mandals, highest neck blast incidence was recorded in Bhimadolu (8.74%). A total of 10 monoconidial isolates of Pyricularia oryzae were established. Out of ten isolates, five were leaf blast (WLB-1 to WLB-5) and five were neck blast isolates (WNB-1 to WNB-5.) The variability in radial growth, colony colour, growth pattern, elevation was studied among the isolates of P. oryzae. Variation existed among the isolates in their conidial dimensions. The longest conidia were observed in the isolate WNB-4 (24.44±0.90) and the shortest conidia in the isolate WLB-1 (18.04±1.58). The broadest conidia were observed in WNB-4 (8.50±1.06) and the narrowest in WNB-5 (6.70±0.96). Molecular identification of P. oryzae isolates with ITS4 and ITS5 universal primers were used in order to support the morphological identification of P. oryzae isolates. All the isolates were appeared as identical by producing the amplified fragment of 560 bp. These results further confirmed the identification of the isolates as P. oryzae. The genetic diversity of P. oryzae isolates was studied using a total of 5 SSR markers. The PIC values ranged from 0.68 to 0.84 with average of 0.78 per marker. The SSR analysis formed two main clusters (I–II) at the Dice similarity coefficient of 0.63. This grouping revealed that, all the isolates were clustered in accordance of leaf blast and neck blast isolates, but not in the specificity of geographical location. A set of 48 genotypes were screened against leaf blast and neck blast during rabi, 2021-22. The same set of genotypes were also profiled for blast resistance genes by using 10 SSR markers. From the phenotypic data 14 genotypes were found as resistant genotypes for both diseases. Eight genotypes viz., LRP 276, Pusa 1882-12-111-7, Pusa Basmati -1, Pusa 1886-13-91-26-9, CR 4156-1-506-2-24, RYT 3437, NLR 20104 and NLR 145 with major R genes i.e., Pi1, Pi2, Pi54, Pita and Pikh combinations were identified as promising lines for rice blast resistance.
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    ThesisItemOpen Access
    STUDIES ON PROGRESS AND MANAGEMENT OF CORYNESPORA LEAF SPOT OF COTTON UNDER HIGH DENSITY PLANTING SYSTEM
    (Acharya N G Ranga Agricultural University, 2023-12-18) PULLURI MOUNIKA; B. SREE LAKSHMI
    The present investigation was undertaken to study the progress and management of C orynespora leaf spot of cotton under High Density Planting System. On infected cotton leaves initially, minute pinhead size light orange to brick red minute spots appeared that gradually enlarged and became circular to oval or irregular concentric spots with tan to light brown centre with yellow halo around the margin. These spots enlarged and concentric zonations were formed resulting in target board symptom. When a roving survey was conducted in cotton growing areas of Guntur district at square initiation stage, boll initiation stage and boll maturity stage for occurrence of C orynespora leaf spot mean PDI was recorded as 13.33 at square initiation stage, 20.23 at boll initiation stage and 25.25 at boll maturity stage. At RARS, Lam, Guntur highest PDI was noticed in cotton cultivar L 1060 at boll formation and boll development stage i.e., 41.25. Multiple regression analysis of Corynespora leaf spot PDI data with weather parameters during kharif 2020-21 revealed that in all the four different spacings of HDPS tested, significant negative correlation was observed between disease severity and RH II, WS and Evap. Area under disease progress curve (AUDPC) was assessed for different spacings. Among the four spacings highest AUDPC was found in 60 cm X 30 cm (645) while the least AUDPC was observed in 75 cm X 45 cm spacing at boll maturity and bursting stage (585). When 150 cotton germplasm lines were screened for resistance against Corynespora leaf spot, 69 entries scoring less than 10% at boll formation and boll development stage were considered resistant. Among the eleven fungicides tested in vitro, the fungicides hexaconazole @ 0.2%, carbendazim @ 0.1%, fluxapyroxad + pyraclostrobin @ 0.06% and metiram + pyraclostrobin @ 0.3% completely inhibited the growth of the pathogen with maximum inhibition of mycelial growth (100%) and significantly superior over all other treatments. Propiconazole @ 0.1% also significantly reduced the radial growth (0.9 cm). Under field conditions all the test fungicides significantly reduced the disease in all spacings when compared to control. After final spray maximum reduction of disease was recorded with fluxapyroxad + pyraclostrobin @ 0.06% (14.3 mean PDI) when compared to control (34.1 PDI) while highest mean PDI was recorded in carbendazim @ 0.1% (22.3). Highest benefit:cost ratio was obtained with propiconazole @ 0.1% i.e., 3.00.
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    ThesisItemOpen Access
    ISOLATION AND EVALUATION OF Bacillus AND Pseudomonas SPECIES FOR PLANT GROWTH PROMOTING AND PATHOGEN SUPPRESSING TRAITS IN SUGARCANE
    (Acharya N G Ranga Agricultural University, 2023-12-18) CHETAN K.K.; P. KISHORE VARMA
    The present study on “Isolation and evaluation of Bacillus and Pseudomonas species for plant growth promoting and pathogen suppressing traits in sugarcane” was conducted at RARS, Anakapalle during 2021-22, where 40 isolates of Bacillus and Pseudomonas species were isolated on specific media with selective supplements from rhizoplane of different sugarcane genotypes. Twenty each of Gram-positive and Gram-negative isolates were further identified as Bacillus and Pseudomonas species respectively by PCR amplification with Bacillus (BCF1 and BCR2) and Pseudomonas (Psmn289 and Psmn1258) specific primers. Morphologically most of the colonies formed by Bacillus isolates were round in shape with even margins, flat, opaque and smooth textured with creamy to milky white pigmentation with few exceptions. In case of Pseudomonas many of the isolates have round or irregular, flat, opaque, smooth textured and creamy to milky whitish colonies with undulated margin with few exceptions. All the 40 isolates were tested for their antagonistic activity against Colletotrichum falcatum and Fusarium sacchari through dual culture assay. Among them six isolates viz., SRB2 (65.74%), SRB4 (54.81%), SRB20 (80.37%), SRP3 (44.26%), SRP19 (80.78%) and SRP20 (69.81%) had significantly inhibited the growth of C. falcatum and five isolates viz., SRB2, SRB20, SRP3, SRP19 and SRP20 have shown inhibition of 52.30, 35.00, 30.93, 46.30 and 39.30% against Fusarium sacchari respectively. The observations at interaction zone revealed variation in growth pattern of the test fungus with hyphal thinning, wrinkling, hyphal tip shearing, protoplasm disintegration, clustering of hyphae and formation of intercellular and terminal chlamydospores. The volatile and non-volatile compounds from the potential isolates substantially reduced the radial growth of C. falcatum and F. sacchari. xvi The highly potential antagonistic isolates (SRB2, SRB20, SRP19 and SRP20) were identified as Bacillus inaquosorum, Bacillus vallismortis, Pseudomonas chlororaphis subsp. aurantiaca and Pseudomonas aeruginosa respectively by partial sequencing of 16S-23S intergenic region amplified by 16F945 and 23R458 primers. All the isolates were qualitatively tested for plant growth promoting and pathogen suppressing traits like, P solubilization (60% of the total isolates), IAA production (30%), protease activity (57.5%), cellulase activity (17.5%), chitinase activity (12.5%), HCN production (10%), siderophore production (27.5%), pyocyanin and fluorescein production (15 and 20% of Pseudomonas isolates respectively) and Antimicrobial peptide (AMP) genes like, fenD (60%), bmyB (50%), spaS (30%) and ituC (30%) for Bacillus isolates and phlD (20%), prnD (20%), phz (15%) and pltC (10%) for Pseudomonas isolates. Sett bacterization had positive impact on sett germination with negligible to very low increase in shoot length and low to higher increase in seedling vigour ranging from 23.85 (SRB1) to 92.91% (SRB11) and 8.80 (SRP14) to 98.73% (SRP17) of increase over control in Bacillus and Pseudomonas treated trays respectively. Sett treatment with potential antagonistic isolates revealed that four (SRB2, SRB20, SRP19 and SRP20) out of six isolates were found effective in controlling pre-emergence and post emergence seedling mortality in C. falcatum and F. sacchari inoculated pots under greenhouse conditions. The isolates SRP19 (Pseudomonas chlororaphis subsp. aurantiaca) and SRB20 (Bacillus vallismortis) were considered to be the most promising isolates in improving plant health as evident by their performance in PGP and disease suppressing activity.
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    ThesisItemOpen Access
    PREPARATION AND EVALUATION OF MICROBIAL CONSORTIA ANTAGONISTIC TO Sclerotium rolfsii, THE INCITANT OF GROUNDNUT STEM ROT
    (Acharya N G Ranga Agricultural University, 2023-12-18) VANAPALLI VASANTHI; P. KISHORE VARMA
    Present study was undertaken to evaluate antagonistic potential of microbial consortia against groundnut stem rot. A total of sixteen fungal and fourteen bacterial bioagents were collected from Department of Plant Pathology, Agricultural College, Bapatla and Agricultural Research Station, Kadiri. Three fungal bioagents-T19007 (80.00%), T19012 (69.26%), T19015 (82.59%) and, three bacterial bioagents- PGP-1 (60.37%), PGP-2 (58.89%) and PGP-13 (73.33%) were found potential in vitro inhibiting S. rolfsii radial growth. The volatiles and non volatiles produced by six potential bioagents inhibited the radial growth of pathogen to varying extents. Volatile metabolites from isolates, PGP-1 and PGP-2 completely inhibited the radial growth of the pathogen.The nonvolatile metabolites (culture filtrate) of T19015 were found to be effective with 79.81 to 83.33% inhibition when tested at 10-30% concentration against S.rolfsii in vitro. Based on 16S-23S rRNA gene sequencing and their analysis through BLASTn search in NCBI database, the potential isolate PGP-13 was identified as Bacillus subtilis with 99.20% similarity. While the characterization of potential fungal isolates through Internal Transcribed spacer (ITS) region gene sequencing revealed that T19007 and T19012 isolates were closely related to Trichoderma asperellum with 95.67% and 98.37% similarity, whereas T19015 was closest match with Trichoderma spp. with 100% similarity. Biochemical characterization of all 14 bacterial isolates revealed that four isolates were tested positive for IAA production and only one isolate produced HCN and none of the isolates were tested positive to siderophore production, cellulase and chitinase activity. While, eight among sixteen fungal isolates were tested positive for cellulase activity and all the isolates were found negative to chitinase activity. The compatibility studies among three potential bacterial antagonists (PGP-1, PGP-2 and PGP-13) revealed that PGP-2+PGP-13 isolates were compatible with each other and two combinations (T19012+ T19015, T19007+ T19015) among three potential fungal antagonists were compatible. Whereas compatibility between potential fungal and bacterial antagonists revealed that the fungal isolate T19012 isolate was compatible with two bacterial isolates PGP-2 and PGP-13. The most suitable and effective isolates were developed into talc-based formulations, and their comparative biocontrol efficacy was assessed in a greenhouse condition. All of the treatments outperformed the pathogen-inoculated control in terms of preventing disease, promoting plant growth, and germination. When seeds were treated with a combination of bioagents rather than a single inoculant, the maximum levels of plant growth and disease control were attained. Fungal consortia (T19012+T19015), when used as a seed treatment alone or in combination with soil application, were found to be more effective than individual and other consortium treatments, potentially offering an alternative to fungicide treatment.