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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Open Access
STUDIES ON THE VARIABILITY OF Rhizoctonia solani Kühn. INCITANT OF RICE SHEATH BLIGHT DISEASE AND ITS MANAGEMENT
(ACHARYA N G RANGA AGRICULTURAL UNIVERSITY, 2024-05-16) YERRAGURAVAGARI SANDHYA; Dr. M. REDDIKUMAR
The present investigation was carried out to study the variability of Rhizoctonia solani Kühn . incitant of rice sheath blight disease and its management. Survey for occurrence and distribution of rice sheath blight disease was conducted in West Godavari, East Godavari, SPSR Nellore, YSR Kadapa and Chittoor districts of Andhra Pradesh during Kharif 2019. Among all the villages surveyed, the highest per cent disease incidence was observed at Penumanchili village (45.66 %) of West Godavari district and the lowest disease incidence was recorded at Koppolu (11.31%) in YSR Kadapa district. A total of thirty pathogen isolates were isolated from the disease samples collected during survey and their pathogenicity was proved in pot culture studies by following typha bit inoculation method. Sheaths from healthy plants in disease- infected field were collected during the survey and thirty bacterial endophytes were isolated from the samples. The cultural variability among the 30 isolates of test pathogen, R. solani was studied on PDA medium. Based on the growth after 72h incubation, ten isolates were categorized into fast growers (65-69 mm growth) and twenty moderate growers (60-64mm growth). Based on the pigmentation of the colony the cultures were assigned to five groups. i.e, ten isolates (Group I- white), three isolates (Group II-Yellowish white), seven isolates (Group III-pale brown), six isolates (Group IV – brown) and four isolates (Group V - dark brown). There was a significant variation among the isolates in the time taken for initiation of sclerotia, which ranged from 5- 9 days, hyphal width varied from the lowest 13.59 μm to the highest 31.66 μm. The colour of sclerotia produced by different isolates was white initially and became dark brown with maturity. Number of sclerotia produced ranged from the lowest 3 to the highest 89. Based on the sclerotia location in the fungal colony, the R. solani isolates were divided into three groups. xx The first group with sclerotia formed in the aerial surface, the second group with sclerotia embedded in the fungal mycelium. The third group with both aerially formed and embedded sclerotia. Pattern of the sclerotia formation was also varied among isolates. Size of the sclerotia ranged from 0.8 to 2.8 mm. Based on texture of sclerotia, isolates were categorized into two groups i.e, smooth and rough. Three rice varieties with varying degree of tolerance to sheath blight disease, viz. NLR-34449 (susceptible), IR-64 (moderately susceptible), Tetep (moderately resistant) was selected for pathogenic variability studies of R. solani isolates. Relative lesion height (RLH) per centage was recorded 10 days after inoculation with pathogen. On NLR- 34449 variety, isolates WAK, NNA, NPC showed highly virulent reaction. WAP, NPP, YVP, YVV, YPL, YPD, YPS and CSS were moderately virulent, however WAA, WTJ, WTM, WTT, ERR, ERV, ERG, EAA, EAM, EAD, NNK, NNN, NPK, YVK, CSA, CSM, CYY, CYK and CYP isolates showed less virulent reaction. On IR- 64 variety, isolate WAK, NNA showed highly virulent reaction. NPC showed moderately virulent response and rest of all the isolates showed less virulent reaction. On Tetep variety, WAK and NNA showed moderately virulent reaction and rest of the isolates showed less virulent reaction. Considering the reaction on all the three rice varieties, isolate WAK showed the highest RLH i.e., 54.66%, 49.03%, and 39.46% on NLR 34449, IR64 and Tetep respectively. WAK isolate was used for further in vitro and field management studies. RAPD analysis was conducted to know the molecular variability among R. solani isolates. Among 20 primers used, eight primers namely; OPA-07, OPA 10, OPB-17, OPC-11, OPC-19, OPE-06, OPF-14 and OPG-11, gave reproducible polymorphism among the 30 isolates. The observed polymorphism among the isolates was 100 per cent in all eight primers. The PIC (Polymorphic Information Content) values were ranged from 0.36 (OPC-11) to 0.49 (OPG-11) with an average PIC value of 0.44 wherein all the primers studied had showed very high variation among the isolates. Genetic relatedness among the R. solani isolates was showed through UPGMA cluster analysis dendrogram. The grouping pattern of the isolates in different clusters indicated that there was less variability among the isolates of the same mandal of one district as they were grouped under same sub cluster except few isolates YVK, YVV, CSM, CYY, YPL, EAD, YVP, NPC and ERR which have separated from their respective mandal isolates and grouped with different sub clusters indicating more variability thus they might had undergone more evolution than others. Hypergeometric probability was calculated among the ten isolates of test pathogen R. solani. Highly virulent to moderately virulent isolates were selected for this studies. WAK, NNA, NPC are highly virulent WAP, NPP, YVP, YVV, YPL, YPD, YPS, CSS are moderately virulent. When the isolates were studied through hypergeometric probability pattern of accidental matching bands gave least probability value (0.014286) between NPC×YVP isolates indicating their accidental similarity is less and they are very close each other and represented in single cluster in dendrogram. Similarly, the next least probability value 0.0833333 was observed between YPS and YPD isolates which are isolated from YSR Kadapa district indicating their close relationship. The highest probability value was between WAK and CSS isolates xxi i.e., 0.978571 indicating that their accidental similarity is more. This means that they have very little association or they are totally different isolates. Eight different fungicides were tested at different concentrations against R. solani were significantly superior over control in checking the mycelial growth. At tested concentrations, 100 % inhibition was observed in all the fungicide treatments except pencycuron. Pencycuron showed decreased inhibition with decreased concentration, 94.77% inhibition at 1500 ppm followed by 93.84 % at 1000 ppm and 92.11% at 500 ppm. Bacterial endophytes were tested against R. solani by dual culture test. NBE-4 bacterial isolate showed highest inhibition of 54.28%. Hence it was selected for characterization studies and in vivo studies like compatibility. NBE4 was rod shaped when observed under compound microscope (1000X) and gram positive in Gram staining test. 16Sr DNA region of potential endophyte NBE4 was amplified using primers 27F and 1492R. 16SrDNA gene sequence of the potential endophyte was compared with gene sequences available at NCBI database through BLASTn search. The gene sequence of the strain NBE4 endophytic bacteria exhibited highest identity of 99.46% with Bacillus sp. strain MR-1/2 (MG548383.1) and its species name was not identified yet. The sequence of the endophyte was submitted to NCBI gene bank and got accession number OK655750. The molecular identity of the strain was confirmed as genus Bacillus species, hence given name as Bacillus sp. NBE4 and it formed a cluster with B. toyonensis, B. mobilis, B. pacificus and B.cereus when a phylogenetic tree was constructed with type strains of genus Bacillus using MEGA (ver. 7) software, which depicts that its sequence was more similar with these species. Eight different fungicides evaluated using poisoned food technique were used to test their compatibility with NBE4 endophyte by using Agar well Diffusion method. Among the tested fungicides, pencycuron 250 SC, azoxystrobin 18.2% + difenoconazole 11.4% SC, iprobenfos 48% EC, showed 0% inhibition of endophytic bacteria i.e., on par at all the concentrations with control (0% inhibition). Among these three, azoxystrobin18.2% +difenoconazole 11.4% SC was selected for field trials because pencycuron showed less per cent inhibition against the R. solani when compared to azoxystrobin18.2% +difenoconazole 11.4% SC. In addition, azoxystrobin18.2% + difenoconazole 11.4% SC not only effective against sheath blight but also against other major rice diseases when compared to iprobenfos 48% EC. Efficacy of certain resistance inducing chemicals salicylic acid, benzoic acid, naphthalene acetic acid, jasmonic acid @ 50, 100, 150 ppm against R. solani were tested in pot culture. Plants treated with salicylic acid showed less disease severity of 20.80% and 20.76% at 100 and 150 ppm concentration, respectively, and both are statistically at par, whereas at 50 ppm concentration disease severity was 22.80% which was significantly higher than the other two concentrations. Induction of defense-related enzymes like PAL (Phenylalanine Ammonia Lyase), Peroxidases and Polyphenol oxidases due to application of resistance -inducing chemicals were estimated at 2,4,6 and 8 days after inoculation. There was significant change in production of these enzymes before application to after application indicating that these chemicals have ability to xxii increase defense enzyme activity in rice plants and activity was increased up-to 6 days and there after decreased gradually. The highest and significant activity of enzymes was found in salicylic acid (SA) treatment and the disease severity also recorded less in this treatment. To know the efficacy of chemicals and bioagent under field conditions an experiment was conducted in both Kharif 2020 and Rabi 2020-21 on NLR-34449 (Susceptible variety) in Randomized Block Design (RBD). In the Kharif, Per cent disease incidence in all the treatments were significantly less as compared to control 63.28% at 70 DAT. Among all the treatments, the lowest per cent disease incidence was recorded in treatment T9 (seed treatment with carbendazim 1g l-1 + seed treatment with bacterial antagonist + root dipping with bacterial antagonist before transplanting + foliar spray with azoxystrobin 18.2% + difenoconazole 11.4% SC @ 1000 ppm + foliar spray of salicylic acid @ 100 ppm) 26.45% and T7 (seed treatment with carbendazim 1g l-1 + seed treatment with bacterial antagonist + root dipping with bacterial antagonist before transplanting + foliar spray with azoxystrobin 18.2% + difenoconazole 11.4% SC@ 1000 ppm) 26.50% which are at par each other and their disease reduction over control was 58.20% and 58.12% respectively. In the Rabi season, per cent disease incidence in all the treatments were significantly less as compared to control 65.99% at 70 DAT. Among all the treatments, the lowest per cent disease incidence 27.73%, 28.00% was recorded in treatment T9 and treatment T7 respectively and both were at par, their disease reduction over control was 57.97 and 57.56% respectively
Open Access
STUDIES ON STEM ROT DISEAS STEM ROT (Sclerotium oryzae Catt.) DISEASEE OF RICE
(ACHARYA N G RANGA AGRICULTURAL UNIVERSITY, 2024-05-16) PICHIGUNTLA RAMANJINEYULU; Dr. T. SRINIVAS
Rice (Oryza sativa) is an important food crop and it is the staple diet of over three billion people around the world, particularly in Asia. Rice diseases caused by fungi are considered the main constraint in rice production and cause both qualitative and quantitative losses. Stem rot disease caused by Sclerotium oryzae Catt. which was considered as a minor disease earlier has now become one of the major limiting factors in rice cultivation. A roving survey on incidence of stem rot of rice in major growing regions of Andhra Pradesh, Telangana and Tamil Nadu states of southern India was conducted during Kharif- 2019. Disease incidence was varied among the locations. The highest mean incidence (5.97%) was recorded in Andhra Pradesh with a range of 3.20 to 9.83, followed by Telangana (2.34) ranged from 1.02 to 3.97 and the lowest mean per cent incidence (2.08%) was recorded in Tamil Nadu with a range of 0.00 to 3.51. Among all the areas surveyed the highest mean per cent incidence (12.92%) was recorded in Karapa mandal with a range of 12.53 to 13.30 and the lowest incidence (0.00%) was recorded in Devakottai block, Sivagangai district of Tamil Nadu. Incidence was observed among all the prominent cultivars of particular region. A total of 36 S. oryzae isolates were isolated from 60 diseased samples. Koch postulated were proved on susceptible rice cultivar Prabhat (MTU3626). Among the isolates, So15 has produced the highest mean per cent disease index (PDI) (39.51) with maximum AUDPC (489.52 units2 ) and an infection rate of 0.065 units day-1. There was no correlation between the virulence nature of S. oryzae isolates with their geographical regions from where they have been collected. Based on the above observation So15 was considered as virulent isolate and used for the subsequent studies. The variability in cultural characteristics among thirty-six isolates of S. oryzae was carried out. There was difference in cultural characteristics such as radial growth of the colony, margin, colour, zonations and sclerotial characters like time taken for initiation, maturation, colour, position and pattern of sclerotia formation (whorls). The highest significant negative correlation was observed between radial growth - sclerotia initiation and radial growth- sclerotia maturation (r2 = -0.52, n=36, p<0.05). There was no correlation between cultural characters and virulence nature of S. oryzae. Cultural variability was evaluated in all the 36 isolates by cluster analysis and dendrogram generated using R (Version 3.4.0) statistical tool. Three major groups (I, II and III) were xviii formed. The group I included seven isolates, group II included a total of nine isolates and group III consists the remaining twenty isolates. ITS region of all the isolates were amplified with ITS1 and ITS4 universal primers. All the isolates were appeared as identical at amplified fragment of 750bp. The genetic diversity of S. oryzae isolates was studied using a total of 27 ISSR primers which given repeated results out of 50 primers screened. A total of 424 alleles and among them 4 monomorphic bands were identified. The percentage of polymorphic loci ranged from 85.70 to 100 with an average 99.03 suggesting high diversity within S. oryzae populations. Cluster analysis based on the UPGMA method using pooled ISSR data (27 primers, 424 loci, 6206 bands) grouped thirty-six S. oryzae isolates into five main clusters (I–V) based on their geographical origin at the Jaccard similarity coefficient of 0.55. The effect of mineral nutrition on the stem rot incidence was assessed under pot culture. The PDI at the initial disease development (52DAS) was the highest in treatments received recommended dose of N, P, Zn, Fe without K (T5) (14.40) and recommended dose of N, K, Fe, Zn without P (T4) (12.35) denoting role of potassium and phosphorus in disease incidence. At 66 days of crop age,the highest PDI (39.51) was recorded in the treatment which received no potassium fertilization with 429.22 AUDPC units2 . There was no significant difference between treatments viz., double the recommended dose of NPK (T2) (24.69; 288.06AUDPC units2 ), recommended dose of N, P, K, Fe without zinc (T6) (24.69; 259.26AUDPC units2 ), recommended dose of N, P, K, Zn without Fe (T7) (23.46; 257.82AUDPC units2 ) and double the recommended dose of N, P, K, Zn, Fe (T9) (23.46; 283.75AUDPC units2 ) which shows that, there was no significant role of Zn and Fe in disease development. The lowest PDI was recorded in recommended dose of N, P, K, Zn, Fe (T8) (18.52; 237.66 AUDPC units2 ) with the highest per cent disease reduction (55.88%) over control. Hence there was a need for balanced fertilization. In the experimentation of effect of abiotic stress on stem rot incidence, the highest PDI(24.69) was recorded under water stagnation conditions with a maximum of 273.66 AUDPC units2 besides, high initial disease development (10.29) and was on par with control (21.60, 190.84 AUDPC units2 ). The lowest PDI(9.26; 90.04 AUDPC units2 ) was recorded in drought and alkalinity conditions. Twenty six rhizosphere bacteria were evaluated for their inhibitory effect on mycelial growth of virulent S. oryzae isolate (So15) in vitro. Among them, RB17 showed the highest per cent inhibition (58.15%) and was considered as potential bioagent and used for further studies. The preliminary cultural and biochemical studies showed RB17 belongs to Bacillus sp. Sequencing of 16s rRNA (1560bp bp PCR product) exhibited 93.15 per cent identity with reference B. subtilis strain ZW (Accession no. CP092369.1) in NCBI database and was named as Bacillus subtilis strain BsIIRR (Accession no. ON024393.1). In vitro evaluation of efficacy of six organic amendments (OAMs) against the virulent isolate of S. oryzae (So15) was carried out. Karanja cake have shown cent per cent mycelial growth inhibition followed by vermicompost (76.67%) and poultry manure (74.44%) at 5 per cent concentration. In evaluation of OAMs on sclerotial germination, none of them were inhibited after 6hr of dipping period. Neem cake have recorded the highest per cent inhibition (73.33%) which was on par with karanja cake (70.00%) after 24hr of dipping period. Even though some organic amendments inhibited mycelial growth failed to suppress sclerotial germination. xix The bio efficacy of twelve fungicides were evaluated against the virulent isolate of S. oryzae (So15) in vitro. All fungicides at all five concentrations inhibited the mycelial growth when compared to control except Validamycin 3% L at 250ppm. Among the fungicides tested, Tebuconazole 250 EC (25.9% w/w) had completely (100%) inhibited the mycelial growth of the pathogen at all five concentrations. In evaluation of fungicides on sclerotial germination, none of them were inhibited after 6hr of dipping period. There is a significant difference between treatments after 24hr of dipping period. Hexaconazole 4% + Zineb 68% WP, Hexaconazole 5% EC, Tebuconazole 250 EC (25.9% w/w) and Difenconazole 25% EC fungicides inhibited one hundred per cent followed by Metiram 55% + Pyraclostrobin (5%) WG, Propiconazole 25% EC and Azoxystrobin 18.2% + Difenconazole 11.4% SC (86.67%). The effective fungicide i.e., Tebuconazole 250 EC (25.9% w/w) and organic amendment i.e., karanja oil cake were tested for their compatibility with the bacterial biocontrol agent, Bacillus subtilis strain BsIIRR (Accession no. ON024393.1) in vitro. The turbidity increased with increase in incubation time as in control which showed compatibility of bacteria with fungicide and organic amendment. The in vitro studies had revealed, Bacillus subtilis strain BsIIRR (Accession no. ON024393.1), karanja cake and Tebuconazole 250 EC (25.9% w/w) as effective against virulent S. oryzae isolate (So15)and were used for in vivo studies. A biointensive management study for control of stem rot was conducted in farmer field at Kaikaram village, Unguturu mandal of West Godavari district of Andhra Pradesh during Kharif- 2020 and Kharif- 2021 on susceptible cultivar MTU1121. Among the treatments, root dipping of seedlings with Bacilluss subtilis strain BsIIRR (ON024393) at 10% + soil application of karanja cake @ 125 kg ha-1 + spraying of Tebuconazole 250 EC (25.9% w/w) @ 1ml/L at 45 and 60 days of crop age (T7) recorded the lowest PDI (15.74) and the highest yield (6.26 t/ha) over all other treatments including control with B:C ratio of 1.76. Hence for the cost-effective management of stem rot, root dipping of seedlings with Bacilluss subtilis strain BsIIRR (ON024393) at 10% + soil application of karanja cake @ 125 kg ha-1 + spraying of Tebuconazole 250 EC (25.9% w/w) @ 1ml/L at 45 and 60 days of crop age proved to be the best
Open Access
STUDIES ON Rizoctronia Bataticola Butler causing Dry Root Rot Desease in Grounbdnut
(Acharya N G Ranga Agricultural University, 2024-05-06) PAMALA PRINCE JAYA SIMHA; Dr.R.SARADA JAYALAKSHMI DEVI
Open Access
“VARIABILITY STUDIES ON Pyricularia grisea [(Cooke) Sacc.] INCITANT OF BLAST DISEASE IN FINGER MILLET AND ITS MANAGEMENT”
(Acharya N G Ranga Agricultural University, 2024-05-06) PADMA ANGADI; Dr. R. SARADA JAYALAKSHMI DEVI
The study was under taken with an aim to know the variability among isolates of Pyricularia grisea causing blast disease in finger millet. Studies were carried out on survey of blast disease to identify the hotspots in major finger millet growing areas of Andhra Pradesh, variability of isolates using cultural, morphological and molecular characteristics and evaluating the bacterial bio-control agents and fungicides against pathogen under in vitro. Efforts were made to identify the promising lines for leaf, neck and finger blasts and knowing suitable weather conditions for occurrence of disease. Attempts were also made to manage the disease with biocontrol agent P. fluorescence, fungicides and their integration. Survey was conducted during Kharif 2020 and Kharif 2021 in seven major finger millet growing districts of Andhra Pradesh. The highest mean blast disease incidence of 56.06% was recorded in Vizianagaram district. The lowest mean disease incidence of 7.85% was recorded in Prakasam district. Regarding mandals, the highest mean blast incidence of 56.59% was recorded in Salur mandal of Vizianagaram district in the range of 53.86 to 59.20% during 2020 and 52.35 to 59.65% during 2021 and lowest incidence of 7.36% with the range of 5.02 to 9.01% and 4.65 to 9.78% was noticed in Racherla mandal of Prakasam district during 2020 and 2021 respectively. The blast samples were collected from different locations of Andhra Pradesh and a total of 20 monoconidial isolates of Pyricularia grisea were isolated. The variability in cultural characteristics viz., colony colour, growth pattern, elevation (flat/elevated growth), sectored or non-sectored, zonations and wrinkle formation were studied among the isolates of P. grisea isolates on Oat Meal Agar medium. Efforts were made to study radial growth sporulation of virulent P. grisea isolate (VIZ-1) in different cultural conditions viz., different media and light conditions. Good amount of sporulation was observed in observed in Finger millet Leaf extract Agar (FLA) medium with 1.81 × 105 ml at 5 days after inocultion followed by OMA with 1.68 × 105 ml at 7 days after inoculation. No significant difference was observed among three light conditions i.e. light (1.07 × 105 ), dark (0.87 × 105 ) and light+dark (0.73 × 105 ). Morphological variability among P. grisea was studied through conidial xvii morphology. Among the isolates, the overall size of the conidia was in the range of 20.74-23.01 μm × 7.00-9.16 μm (Length × Width). The molecular variability of P. grisea isolates was studied using 25 SSR markers, of which seven were polymorphic. The genetic diversity was ranged from 0.180 (MGM 437) to 0.742 (Pyrms 63) with an average of 0.491. Dendrogram using Neighbor Joining (NJ) resulted in formation of three mega clusters in which cluster I was further sub grouped into sub-cluster IA, which includes eight isolates and sub cluster IB contains one. Cluster II was further sub grouped into sub-cluster IIA, which includes six isolates and sub-cluster IIB includes only one isolate. However, cluster III was further divided into sub cluster IIIA which includes three and IIIB includes only one isolate. The RAPD analysis revealed that, out of 8 RAPD primers, 7 primers produced polymorphic alleles which were selected for genetic diversity analysis. A total of 84 reproducible alleles with an average of 12 fragments per primer were produced using 7 RAPD primers. All the markers displayed polymorphic alleles. Of the total alleles (84), one allele (OPA-07) was monomorphic with 15.38% monomorphism and 84.61% polymorphism which contains two monomorphic bond with PIC value of 0.2874. Whereas 6 primers produced 100% polymorphism with PIC value ranged from 0.1769 to 0.3429 and total number of polymorphic bands were ranged from 8 to 14. Dendrogram constructed to reveal the pattern of relatedness among twenty P. grisea isolates using DARwin 6 software on the basis of RAPD polymorphism. Cluster I is further divided into sub-cluster IA which consisting of nine isolates Sub-cluster IB of with two isolates. Cluster II further divided into cluster IIA which consisting of four isolates and sub-cluster IIB contains only one isolate. However, cluster III further divided into sub-cluster IIIA which contains three isolates and sub-cluster IIIB contains only one isolate. A total of 23 bacterial bio-control agents were isolated from rhizospheric soil of healthy finger millet plants and three isolates were collected from ARS, Vizianagaram for in vitro studies. Bacterial bio-control agents were evaluated for their antagonistic effect on P. grisea under in vitro conditions. Results revealed that, maximum inhibition of mycelium growth (79.54%) was noticed in BVP-1isolate and least mycelial inhibition was noticed in BJR (11.30%) isolate. Studies on In vitro evaluation fungicides against the pathogen revealed that Tricyclazole 75% WP, Carbendazim 50% WP and Tebuconazole 50% + Trifloxystrobin 25% WG inhibited the mycelial growth completely. Compatibility studies of fungicide and bio-agent revealed that Tebuconazole 50% + Trifloxystrbin 25% WG and Carbendazim 50% WP at all concentrations were found to be compatible with zero per cent inhibition of bacterial bio-control agent. 74 lines of finger millet including local check VR 708 were screened for their resistance against blast in field conditions. Results showed that for leaf blast five lines were found as highly resistant, 31 lines found as resistant, 23 lines were recorded as moderately resistant and 15 lines were found to be susceptible. For neck blast, 30 lines were recorded as resistant, 29 lines shown moderately resistant, 15 lines were reacted as susceptible. Out of 75 lines screened, 20 lines showed moderate resistance, 41 lines with susceptible reaction and 14 lines including VR 708 showed highly susceptible reaction to finger blast incidence. xviii Correlation and regression analysis of weather parameters with disease development revealed that blast disease severity was shown to be higher during the early planting window, possibly due to comparatively high relative humidity, rainfall and a greater number of rainy days, all of which favor disease development. The effective fungicides and potential bacterial bio-control agent were used in integrated disease management of finger millet blast at S.V. Agricultural College, Tirupati and ARS, Vizianagaram during Kharif 2021, the treatment T7 and T8 were found effective for leaf, neck and finger blast with yield.
Open 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).
Open Access
EPIDEMIOLOGY AND MANAGEMENT OF YELLOW MOSAIC DISEASE INFECTING BLACKGRAM (Vigna mungo (L.) HEPPER)
(Acharya N G Ranga Agricultural University, 2023-12-07) VALLABHANENI TILAK CHOWDARY; V. MANOJ KUMAR
In the present investigation on “Epidemiology and management of yellow mosaic disease infecting blackgram (Vigna mungo (L.) Hepper)”, four major blackgram growing districts viz., Krishna, Guntur, West Godavari and Prakasam of Andhra Pradesh were surveyed for the incidence of yellow mosaic disease (YMD). Disease incidence among various districts ranged from 14.58% to 23.04% indicating the impact of disease. Fifteen weed species, showing typical mosaic symptoms were collected out of which six weeds viz., Abelmoschus moschatus, Ageratum conyzoides, Amaranthus viridis, Desmodium laxiflorum, Parthenium hysterophorus and Vigna trilobata, were found positive for Mungbean yellow mosaic India virus (MYMIV). First time, A. moschatus and D. laxiflorum were reported to have infected with Mungbean yellow mosaic India virus when confirmed using PCR detection. Association of betasatellite ( ̴1.3 kb) and MYMIV in A. moschatus was also reported for the first time, which defines the movement of MYMIV into new hosts and association with the already existing betasatellites. Molecular characterization based on coat protein revealed that the test isolates viz., YMV-KR from Krishna district (MZ475993), YMV-GN from Guntur district (MZ475994), YMV-WG from West Godavari district (MZ475996), YMV-PR from Prakasam district (MZ475995), YMV-ABEL from A. moschatus (MZ475997) and YMV-DES from D. laxiflorum (MZ475998) belong to MYMIV and none of them showed positive to MYMV. Hence it was concluded that YMD isolates of blackgram in surveyed areas of Andhra Pradesh were closely related to MYMIV (old world geminiviruses) than MYMV (New world geminiviruses). The sequence analysis of six isolates using SDTv1.2 revealed that YMV-GN and YMV-DES shared 99.58% homology, which was the highest among test isolates xv whereas, least homology of 94.85% was found between YMV-PR and YMV-WG. Isolates of the two weed species YMV-DES and YMV-ABEL shared an identity of 99.30% at nucleotide level. The isolates collected from crop species i.e., YMV-KR, YMV-GN, YMV-WG, YMV-PR shared a nucleotide similarity of 94.85-97.77%. Phylogenic analysis based on coat protein revealed that two isolates from Krishna district and West Godavari district varied with isolates collected from Guntur and Prakasam. The whole genome characterization of causal organism of YMD revealed a novel recombinant isolate (YMV-BG-BPT) from blackgram in Andhra Pradesh. The association of a bipartite begomovirus with the disease was confirmed by sequence analyses of the cloned full-length genome. The sequence analysis of DNA-A (MZ235792) of YMV-BG-BPT showed maximum of 99.12% similarity at nucleotide level with Mungbean yellow mosaic India virus (MYMIV) isolate reported from Tamil Nadu, India (KC911719), which was also confirmed by clustering pattern in phylogenic analysis. The sequence analysis of DNA-B (MZ356197) showed 95.79% with Mungbean yellow mosaic virus (MYMV) isolate reported from Tamil Nadu (KP319016) and 95.05% with Mungbean yellow mosaic India virus (MYMIV) isolate reported from Karnataka (MT027037). The huge variation in DNA-B, was further confirmed by detecting a recombinant event in the intergenic region (IR), region coding for nuclear shuttle protein and movement protein in which MYMV-BG-AP-IND (KF928962) and MYMIV-GG-CH-IND (MN020536) have been identified as major and minor parents, respectively. To the best of our knowledge, this was the first molecular confirmation and characterization of blackgram infecting MYMIV with a recombinant DNA-B in Andhra Pradesh, India. During epidemiological studies (2019-2021), among the three sowings, Min T had showed negative correlation with both whitefly population and disease severity during first and second sowing. However, in the third sowing negative correlation with Min T was taken over by RHE in terms of whitefly population while the same was taken over by RHM in terms of disease severity. During the entire study, whitefly population had shown positive correlation with disease severity. The epidemiological studies conducted during present investigation indicated that first sowing of blackgram (2nd fortnight of October) had lesser YMD severity while late sowings favoured development of disease due to favourable weather conditions for buildup of whitefly and thereby the disease. Management studies with different insecticides and botanicals revealed that flonicamid 50 WG @ 0.4 g l-1 was effective in reducing whitefly population with a mean reduction of 67.52% and 61.01% at first and second spray, respectively over control, while among the botanicals cotton seed extract 5% (Gossypium herbaceum) was found effective with a mean whitefly reduction of 22.83% and 22.09% at first and second spray respectively over control. Among chemicals, flonicamid 50 WG @ 0.4 g l-1 treatment recorded least disease incidence (72.33%) and severity (68.24%), while the botanical ramaphal leaf extract 5% (Annona reticulata) has recorded with least disease incidence (85.02%) and severity (55.44%). Among all the treatments, AUDPC was highest in the control (1313.27) while least was recorded in flonicamid 50 WG @ 0.4 g l-1 (653.04). Among the botanicals, ramaphal leaf extract 5% showed least AUDPC (1006.83) when compared to turmeric corm extract 5% (1091.40) and cotton seed extract 5% (1096.44). Highest yield was recorded in flonicamid treated plots (537.39 kg ha-1) followed by acetamiprid (453.33 kg ha-1) whereas, among the botanicals ramaphal leaf extract treated plots recorded a yield of 340 kg ha-1.
Open Access
ROLE OF MINERAL NUTRITION IN GROUNDNUT LATE LEAF SPOT DISEASE DEVELOPMENT
(Acharya N G Ranga Agricultural University, 2023-12-07) DASU RAMA SRI VINEELA; P. ANIL KUMAR
The present investigation on "Role of mineral nutrition in groundnut late leaf spot disease management" was carried out at the Department of Plant Pathology and College farm, Agricultural College, Bapatla during 2019-20 and 2020-21. In the present investigation, plant and pathogen traits governing groundnut late leaf spot disease were assessed by growing susceptible cultivar (K-6) and tolerant cultivar (Kadiri Harithandhra) in sand culture and artificially inoculated with P. personata. The data obtained indicated that prolonged latent period (17 days) and less number of lesions (28.6/leaf), smaller lesion size (1.7 mm) and increased anti-oxidant enzyme activity (SOD, POD and CAT) might have resulted in decrease in turn chlorophyll senescence/ loss (28.80%) due to pathogen which accounted for tolerance in Kadiri Harithandhra compared to susceptible K-6 (latent period:14 days, lesion number: 57/leaf, lesion diameter: 2.5mm, decrease in chlorophyll content: 39.63%). Thus, these pathogenic and plant traits were used to assess role of mineral nutrition in incorporating tolerance to LLS susceptible variety i.e., K-6. Direct effect of nutrients on P. personata conidia revealed that lack of majority of nutrients except P and Ca had no direct effect on P. personata conidial germination (61.73% and 66.20%) and number of germ tubes (1.22) respectively. However, germ tube length was greatly enhanced in K and Mg deficient solutions while in Zn and N deficient solution, the same was decreased. Deficiency of nutrients especially K, Mg, S, Cu aggravated the disease by encouraging pathogen through decreased incubation (4,4,5 and 7 days respectively) and latent periods (8, 8, 7.33 and 11 days respectively), increased lesion number (22.00, 21.67, 22.33, 14.67/leaf respectively) and lesion diameter (2.83, 2.73, 3.03 and 2.70 mm) thus higher AUDPC values (19.33, 24.67, 32.00 and 10.67) compared to control (7 days incubation period, 11 days latent period, 8.33 lesions/leaf with xvi lesion diameter 2.70 mm and AUDPC value 6.67) which further impaired chlorophyll content (0.98, 0.73, 0.66, 0.74mg/g against 0.97 mg/g in control) and anti-oxidant enzyme activity which act as primary defence mechanism in scavenging reactive oxygen species during hemibiotropic pathogen infection. Visual deficiency symptoms and nutrient content in leaves further confirmed the role of nutrient deficiencies in aggravating LLS disease and hence effect of supplementation of these nutrients K, Mg, Cu and S in managing LLS were studied. CuSO4 twice the strength had similar affect as fungicidal check (6.33 and 9.67 days) in delaying incubation (6.33 days) and latent periods (8.67 days) while KNO3 thrice the strength, MgSO4 thrice the strength has similar effect as fungicidal check (2.00/ leaf and 1.00 mm) with respect to lesion number (3.00/leaf) and lesion diameter (1.00 mm) resulting in lesser AUDPC values as fungicidal check compared to absolute control (4 days incubation period, 7.33 days latent period, 10.33 lesions/leaf, 2.50 mm diameter). SOD and POD enzyme activities showed similar trend corresponding to incubation period and latent period when comparing antioxidant enzyme activity of nutrient supplemented treatments and fungicidal check with tolerant cultivar indicating that adequate amount of nutrient supplementation to plants offers tolerance to fungal infection through altered antioxidant enzyme activity. Supplementation of CuSO4 and MgSO4 were effective in reducing disease when applied through soil during initial stages by prolonging incubation (13.67 days and 13.33 days) and latent period (8.33 and 8.67 days) but with increase in age of the crop, foliar sprays were found more effective in reducing lesion number (2.67/ leaf, 4.00/leaf) with lesser diameter and AUDPC as fungicidal check (13.67 days incubation period, 9.67 days latent period, 2.00 lesions/leaf with 1.00 mm diameter). CuSO4 and combination of four nutrients were effective in delaying incubation (11.67 days, 12.33 days) and latent period (16.67 days, 17.00 days) while MgSO4 followed by combination of four nutrients were effective in reducing lesion number (17.65/leaf, 22.15/leaf) and diameter (0.20 and 0.27 mm) thereby reduction in AUDPC values. Nutrient supplementation, though inferior to fungicidal check (14 days, 18.33 days, 1.95 lesions/leaf with 0.22), was significantly superior than absolute control in reducing disease (10.33 days incubation period, 13.67 days latent period, 70.15 lesions/leaf with 0.33mm diameter). Nutrient solutions of S at 0.5%, K2SO4 at 0.5% and CuSO4 at 0.2% had inhibitory effect on conidial germination while combination of nutrients reduced germination percentage (4.53%) and germ tube length. Pooled analysis of the field experiments conducted during rabi and summer 2020-21 revealed that Cu+S and K+Cu+Mg+S were effective with least LLS incidence (54.58% and 54.97%) and were on par with fungicidal check (47.77%). Further, Cu+S supplementation results in higher pod yield (1766.67 kg/ha) with highest rate of returns (3.16) and found superior to fungicidal check (1572.22 kg/ha and 2.60).
Open Access
CHARACTERIZATION AND MANAGEMENT OF EMERGING PATHOGEN, CORYNESPORA IN COTTON
(Acharya N G Ranga Agricultural University, 2023-12-07) BANDI MOHAN VENKATA SIVAPRASAD; B. SREE LAKSHMI
In the present investigation on “Characterization and management of emerging pathogen, Corynespora on cotton”, during kharif, 2019-20 & 2020-21 survey in five major cotton growing districts of A.P. revealed PDI of Corynespora target spot ranged from 26.8% to 50.9% and 19.6% to 37.5% in kharif, 2019-2020 and 2020-2021, respectively. Pure cultures of 21 isolates showed considerable variation in cultural characters such as texture, shape of the colony, colony elevation, growth habit, nature of mycelium, number of concentric rings, pigmentation on top of culture plate, pigmentation at bottom of culture plate and morphological characters such as conidial length, width and number of pseudo septa. Based on the characters studied, 21 test isolates were categorized into different groups. The incubation period varied from 4 to 6 days. Among all the isolates, CPIK-1909 isolate was found highly virulent with low incubation period (4 days) resulting in more lesions (42.40±3.34) and highest PDI (50.50). Multivariate analysis used for cultural, morphological and pathogenic characters revealed formation of six clusters based on Euclidean distance values. Characterization of 21 Corynespora cassiicola isolates was performed using ITS 1 and ITS 4 primers. PCR amplification using ITS region resulted in an amplicon of 550 bp. Sequences of six isolates (CGGL-19001, CGGG-19004, CPIK-19009, CKGV-19011, CYPP-19016 and CKDR-19018) were deposited in NCBI (MZ314930, 29, 28, 27, 25 and 26). Molecular variability was determined for the 21 test isolates using four RAPD primers which resulted in a total of 47 bands with polymorphism having band size ranged from 300 to 2500bp. Dendrogram obtained had two clusters (PL1 and PL2), PL1 consisted of single isolate (CYPG-19017) and PL2 consisted remaining 20 isolates. xx Pooled analysis of two seasons (kharif, 2019-2020 and 2020-2021) showed that PDI of Corynespora target spot was significantly and positively correlated with Tmax, Tmin, RF and WS and expressed negative correlation with SSH and Evap. Regression studies revealed that Tmax, Tmin, RHII and Rd influenced the Corynespora target spot in cotton upto 96.5%. Step up and step down regression analysis indicated that individually Tmax, Tmin, RF, SSH, WS and Evap. influenced up to 56.0, 51.6, 25.1, 48.0, 42.5 and 35.0% respectively. Pooled analysis for yield loss estimation (kharif, 2019-2020 and 2020-2021) revealed 26% of yield loss if management practices were unattended. Minimum of four sprays of propiconazole @ 0.1% were required to nullify the loss in yield (24%) due to cotton Corynespora target spot depending on weather conditions. PDC and yield showed positive correlation with number of sprays whereas PDI was negatively correlated with number of sprays. Yield and avoidable yield loss negatively correlated with number of sprays. The test pathogen, Corynespora was found to be both externally and internally seed borne. Among the externally seed borne mycoflora, Corynespora and Aspergillus spp. were associated with cotton seeds. In case of internally seed borne association, Corynespora ranged from 2 to 18% and showed higher association than other fungi. The seed mycoflora of cotton exhibited different distribution pattern among which, Corynespora and Aspergillus exhibited highest colonizing frequency (CF) and Isolation recovery (IR) in case of externally seed borne infection. In case of internally seed borne infection, CF and IR of Corynespora was found to be the highest among all the fungi observed. For externally seed borne mycoflora, the highest Simpson’s diversity index (DI=0.826), Shannon – Wiener diversity index (H’=1.846), species richness (1.219) and Species evenness (0.949) were recorded in samples of Jaadoo BG II. For internally seed borne fungi, highest DI of 0.794 was in LHDP-1 followed by NDLA-2463 (DI=0.792) having highest H’ (1.657) with Species richness (1.429) and Species evenness (0.851). Based on in vitro poisoned food technique, dual culture and detached leaf technique studies, propiconazole, carbendazim+mancozeb, four biocontrol agents (T18001, PF1, BS2 and ACT1) and salicylic acid @ 5 mM were utilized for field studies. Pooled data for management studies (kharif, 2019 and 2020) showed lowest disease severity in foliar spray with propiconazole at 0.1% (12.4 PDI), highest yield (2931.7 kg ha-1) and BC ratio 1.46 was found on par with carbendazim+mancozeb at 0.1% (13.9 PDI, 2851.1 kg ha-1 and 1.42) and significantly superior to other treatments as against control (27.3 PDI, 2265.6 kg ha-1 and 1.13) respectively.
Open Access
STUDIES ON Tobacco streak virus (TSV) CAUSING PEANUT STEM NECROSIS DISEASE (PSND) AND ITS INTERACTION WITH Groundnut bud necrosis virus (GBNV) IN GROUNDNUT (Arachis hypogaea L.)
(guntur, 2022-08-17) SARATBABU, K.; VEMANA, K.
Groundnut is an annual legume crop grown in diverse environment over the world between 40oN and 40oS. Among the viruses infecting groundnut, Tobacco streak virus (TSV) causing peanut stem necrosis disease (PSND) and Groundnut bud necrosis virus (GBNV) causing Peanut bud necrosis disease (PBND) are major constraints for groundnut cultivation in India. Extensive survey was so far not conducted in groundnut growing districts of A.P. and very limited research was carried out regarding screening of groundnut genotypes against PSND in both field and artificial conditions in glass house. Cloning of resistant gene analogues (RGA), morphological and biochemical parameters responsible for resistance against PSND in groundnut genotypes were not attempted. Further, mixed infection of TSV and GBNV, and their combined impact on groundnut cultivation have not been studied to date. In this context, diagnostic surveys were conducted to determine the incidence of viral diseases in groundnut growing districts of Andhra Pradesh (A.P). Studies on identification of resistance sources against TSV in groundnut genotypes through natural infection and artificial sap inoculation, identification of resistance to Tobacco streak virus (TSV) using resistance gene analogue in groundnut genotype and interaction of TSV and GBNV in groundnut was carried out at Agricultural Research Station, Kadiri from 2017 to 2020. Roving survey was conducted for assessing the incidence of viral diseases in 12 districts of A.P. during kharif and rabi 2017-18. Major viral diseases such as PSND and PBND was observed during the survey. Mean PSND incidence was significantly higher in kharif 2017-18 (7.4%) compared to rabi 2017-18 (6.5%) in groundnut growing districts of A.P. The present study recorded PSND incidence for the first time from four coastal A.P. districts (Krishna, Guntur, Sri Pottisriramulu Nellore, Prakasham) with confirmation using DAC-ELISA and RT-PCR. The partial coat protein (CP) gene of TSV-GN-INDVP groundnut isolate shared wide range of nucleotide identities (80.72-98.62 %) with isolates reported globally. Present study isolate shared 97.97-98.51% xiv nucleotide identities with groundnut isolates and 97.51-98.62 % nucleotide identities with other crop TSV isolates from India. Of the 70 fields surveyed, spread over twelve districts of A.P., 66 fields showed infection of GBNV revealing wide spread occurrence of the disease in A.P. Roving survey revealed that PBND incidence was significantly higher in rabi 2017-18 (13.6%) compared to kharif 2017-18 (5.3%) in groundnut growing districts of A.P. Partial nucleocapsid (N) protein gene of GBNV-GN-BPIND groundnut isolate shared high range of nucleotide identity (78.66-98.48 %) with other GBNV isolates reported from different crops and locations. GBNV-GN-BPIND isolate shared 96.67-97.73 per cent nucleotide identity with groundnut isolates and 96.59–98.48 per cent nucleotide identity with GBNV isolates of other crops from India. Sixty-two genotypes (Elite, pre-released and interspecific cross derivatives) screened against PSND for two seasons (kharif 2017-18 and kharif 2018-19) by Parthenium infector border and natural conditions (without infector border). Field screening of genotypes revealed that the genotypes ICGV-06175, ICGV-06145, ICGV-06149 and genotypes viz., K-7 bold, Kadiri Lepakshi, K-9, K-1909 performed consistently highly resistant and resistant reaction respectively in field conditions for two seasons (kharif 2017-18 and 2108-19). Above resistant genotypes along with susceptible genotypes viz., ICGV07120, K-1811, Kadiri Harithandra, Kadiri Amaravathi, K-2269 (E), K-1482K-, ICG14373, K-1628 (HY), K-2270, GPBD-4, 1501 (FDR), 1559 (FDR), Kisan were selected for further studies under glasshouse condition to confirm their resistance against TSV by mechanical sap inoculation at 14 DAS. The per cent disease incidence was recorded 3-10 days’ post inoculation (DPI) ranged from 37.5 to 100% among the genotypes. The minimum incidence was recorded in ICGV-06175 and showed significant difference with other genotypes. The genotypes grouped under highly resistant, resistant categories in field screening became susceptible in glasshouse during TSV sap inoculation. The genotypes which are given highly resistant (ICGV-06175, ICGV-06145, ICGV-06149), resistant (K-7 bold, Kadiri Lepakshi, K-9, K-1909), susceptible (Kisan) reaction under field condition were selected to isolate RGAs using PCR based approach and successfully isolated RGAs from genomic DNA of TSV highly resistant, resistant and susceptible groundnut genotypes. As compared to highly resistant and resistant genotypes, susceptible genotype showed faint band amplification and analysis of derived peptide sequences revealed that deletion of amino acid sequence in P-loop motif and expressed shift of amino acids such as aspartic acid (D) to serine (S) and leucine (L) to valine (V) in non-TIR-NBS LRR sub family when compared to resistant and tolerant genotypes. In highly resistant genotypes RGA clones viz., RGA 12 (ICGV06175) and RGA14 (ICGV06145) in TIR- NBS LRR sub family expressed shift of amino acid leucine (L) to serine (S) when compared to resistant and susceptible genotypes. During simultaneous inoculation no synergism was observed between TSV and GBNV, while a slight antagonism was observed between these viruses. But this antagonism reaction didn’t help the plant in avoiding disease. Based on reaction under high disease pressure (using Parthenium infector border) under field condition and artificial sap inoculation under glasshouse conditions the genotype ICGV06175 was identified as highly resistant against PSND and can be used in breeding program as a resistant source against PSND. The isolated RGAs from groundnut genotypes can be used for characterization of different resistant genes and can be explored in the development of disease resistance molecular markers.

Acharya N G Ranga Agricultural University, Guntur

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