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
DYNAMICS OF NITROGEN AND PHOSPHORUS UNDER MAIZE - BLACKGRAM - GROUNDNUT CROPPING SEQUENCE IN RED LOAMY SOILS
(Acharya N G Ranga Agricultural University, 2024-05-23) BELLARY USHASRI; Dr. T. GIRIDHARA KRISHNA
A field experiment entitled “Dynamics of nitrogen and phosphorus under maize - blackgram - groundnut cropping sequence in red loamy soils” was conducted (2019-2020) at S.V. Agricultural College, wet land farm, Tirupati. The experimental soil was sandy loam in texture, slightly acidic in reaction, low in organic carbon and available nitrogen, high in available phosphorus, medium in available potassium. All the micro-nutrients (Mn, Zn and Cu) were above the critical limits, except Fe. The experiment was laid out in a randomized block design and replicated thrice. Ten treatments viz., control, fertilizers applied at 50, 75 and 100% of the recommended dose (N240P80K80), N240 only, P80 only, FYM (@ 5 t ha-1) applied alone, and in combination with100%,75% and 50% recommended NPK were applied to maize. These treatments were compared with no-fertilizer and manure control. Blackgram was grown following maize without any fertilizer or manure application. It was allowed to grow till maturity, and after two pickings, the stover was incorporated into the soil. On the same field where blackgram was grown, each main plot treatment of RBD was split into three sub plot treatments with three levels of recommended dose of fertilizers viz., S1 (control), S2 (75% RDF) and S3 (50% RDF) resulting in ninety treatment combinations replicated three times in split plot design and groundnut grown as test crop in kharif. Application of organic manures and inorganic fertilizer showed the influence on physico-chemical properties of soil at harvest in maize, the highest organic carbon (0.56%), available nitrogen (110 kg ha-1) and phosphorus (35.1 kg ha-1) in soil were recorded with application of 100% RDF (T3) and this was on par with 100 % RDF+ FYM @ 5 t ha-1 (T8) and 75 % RDF + FYM @ 5 t ha-1 (T9) in case of organic carbon and phosphorus. Among subplots, S2 is significantly superior over S3 and S1 pertaining to available nitrogen (112 kg ha-1) and phosphorus (24.0 kg ha-1). The highest blackgram haulm yield was obtained in the treatment T3 (6472 kg ha-1) where 100% RDF was added to maize. The higher N, P and K uptake of blackgram at flowering was registered by T9 (212, 71.3 and 214 kg ha-1 , respectively). xviii Among the treatments applied to maize T8 (100 % RDF+ FYM @5 t ha-1) resulted in higher groundnut pod, haulm yield and total dry matter of 2426, 2363 and 4789 kg ha-1 respectively. While S2 (75% of recommended dose for groundnut) recorded the highest pod, haulm yield of 2256 and 2443 kg ha-1 and total dry matter of 4699 kg ha-1 and it was superior to the S3 and Sl . The highest available N, NH4-N and NO3-N content of 131, 17.2 and 38.5 mg kg-1 soil were maintained under the treatment T3, where optimum dose of NPK was applied. The values of total, available, NH4-N and NO3-N further decreased, T3 (100% RDF) recorded the highest as 110, 9.5 and 27.3 mg kg-1 at maize harvest. The treatments T6 (17.8 mg kg-1) and T3 (27.2 mg kg-l) showed substantial increase in the NH4-N and NO3-N content of the soil at 50 % flowering of groundnut and decreased at harvest. Among the organic N fractions viz., hydrolysable organic amino sugar N (ASN), amino acid N (AAN) and ammonia N (NHN) were significantly higher with application of 100 % RDF (T3), however, it was on par with that of application of 100% RDF + FYM @ 5 t ha−1 (T8), 75 % RDF + FYM @ 5 t ha−1 (T9), 75 % RDF (T4) and 100% N (T6) under all the crops throughout the cropping period. The subplot treatment S2 (75% of recommended dose) was superior to S3 and S1 in influencing the Olsen P content of the soil. These treatments also maintained higher values of the inorganic P fractions (LB - P, Al - P, Fe - P, RS- P, Occl - P and Ca - P). Among all, calcium bound P (Ca-P) was the most dominant P fraction in the experimental soil, comprising about 15-33% of the total inorganic P, next dominant fraction was the reductant soluble P (RSP), constituting 14 to 22% of inorganic P. Residual P content of the soil was highly variable, with values ranging from 4.5 to 36.5%. Total-N, available N, NH4-N and NO3-N content of the soil at silking stage of maize positively affected maize yield and N uptake at maturity. Organic N content of soil at maize harvest stage could significantly relate with grain yield and stover yield (r = 0.730*, 0.637*), grain, stover N uptake (r = 0.716*, 0.745*) and total N uptake (r = 0.753*). Particularly AAN, ASN and NHN hydrolysable N fractions positively influenced the maize yield, N uptake of grain and stover during all the stages. Among the hydrolysable N fractions AAN, ASN and NHN exhibited significant correlation with total yield and N uptake, at flowering stage (r values were 0.788** and 0.855**, respectively in case of AAN, 0.880**, 0.926** and 0.728*, 0.812**, respectively in case of ASN and NHN). Hyd.N fractions determined at flowering and harvest stages of groundnut influenced yield and N uptake, with UIN exhibiting negative values of 'r'. Inorganic P content of soil at silking stage of maize correlated significantly with total yield (r = 0.707*) and total P uptake (r = 0.772*). The total yield (r = 0.644*) and P uptake (r = 0.664*) by maize were found to be significantly correlated with LB-P fraction at the harvest. Phosphorus uptake by both grain and haulm was significantly influenced by all fractions except Res-P at flowering stage as well as before incorporation of blackgram. Both yield and P uptake by groundnut were direct functions of total, inorganic and Olsen P at before sowing, 50% flowering and at harvesting of groundnut. LB-P during all the growth stages of groundnut was found to influence both yield and P uptake. xix Ammonical-N (NH4-N), ASN and UIN contents of soil at silking stage of maize could explain the variation in maize yield to the extent of 63.1% and at the harvest stage, NO3-N fraction of soil inorganic N could predict the grain yield to the extent of 56.4 %. While pod yield of groundnut was predicted to an extent of 88.0% with the help of UIN, NH4-N, ASN, NO3-N and NH3 - N fractions of soil N. The soil inorganic fractions of P, viz., Org-P, LB-P, Al-P, RS-P and Occ-P determined before sowing of groundnut were found to explain the variability in pod and total yield at maturity to an extent of 98.8 and 98.1%.
Open Access
DETAILED SOIL RESOURCE INVENTORY OF VARATHURU WATERSHED IN CHITTOOR DISTRICT OF ANDHRA PRADESH USING REMOTE SENSING AND GIS
(Acharya N G Ranga Agricultural University, 2024-05-23) G.P. LEELAVATHY; Dr. M.V.S. NAIDU
The present investigation entitled ''Detailed soil resource inventory of Varathuru watershed in Chittoor district of Andhra Pradesh using remote sensing and GIS'' involves study of twentyone (21) typical pedons for morphological, physical, physico-chemical and chemical properties in the Varathuru watershed. Inaddition, two hundred and fifty six (256) surface soil samples (0-15 cm) were collected with GPS coordinates and were analyzed for pH, EC, organic carbon, macronutrients (N, P2O5, K2O and S) and micronutrients (Zn, Cu, Fe and Mn) and were mapped by using ArcGIS v 10.3. The study area was characterized by semiarid monsoon climate with distinct summer, winter and rainy seasons. The pedons occurs in plains (P7 and P8), very gently sloping (P1, P2, P5, P11, P14 and P18), gently sloping (P3, P4, P15 and P17), moderately sloping (P6, P9, P10, P12, P13 and P16), Very strongly sloping (P19 and P20) and moderately steep sloping (P21) topography. All the pedons in watershed were developed from granite-gneiss. The morphological features indicated the presence of AC/AR (P3, P15, P19 and P21), ABC (P1, P2, P5, P7, P8, P9, P11, P13, P14, P17, P18 and P20), A-AB/BA C (P4, P6, P10 and P16) and A-A/B-C (P12) profiles. The soils were shallow to deep in depth, dark reddish brown to light yellowish brown in colour, gravelly sandy loam to sandy clay loam in texture and exhibited single grain, granular and sub-angular blocky structures. The clay content in P3, P9, P12, P13, P16 and P20 exhibited an increasing trend with depth whereas no specific trend with depth was observed in the remaining xvii pedons. Physical constants like water holding capacity and volume expansion followed the trend of clay content. The soils of Varathuru watershed were slightly acidic to moderately alkaline (6.03 to 8.35) in reaction (pH), non-saline (0.02 to 0.40 dS m-1 ) and low to medium (0.04 to 0.74%) in organic carbon. The CaCO3 content was ranged from 0.60 to 8.68 per cent and ESP was low (0.39 to 10.80 %). The CEC values were ranged from 4.68 to 33.49 cmol (p+ ) kg-1 and the exchange complex was dominated by Ca2+ followed by Mg2+, Na+ and K+ . The Varathuru watershed soils were low (25.10 to 262.50 kg ha-1 ) in available nitrogen, low to high (8.91 to 94.05 kg P2O5 ha-1 soil) in available phosphorous and potassium (116.45 to 551.60 kg K2O ha-1 ) and deficient to sufficient (1.75 to 52.56 mg kg-1 ) in available sulphur. The soils were sufficient in DTPA extractable Cu and Mn and deficient to sufficient in DTPA extractable Zn and Fe. The mineralogy class for all these was mixed based on CEC / clay ratio. Based on the morphological, physical, physico-chemical, mineralogical and meteorological data, the soils were classified as Entisols, Inceptisols and Alfisols and these soils were further classified at family level as: Pedons 1, 4, 6, 7, 10, 12, 16 and 20 : Fine loamy, mixed, isohyperthermic, Typic Haplustepts Pedon 3 and 15 : Fine loamy, mixed, isohyperthermic, Typic Ustorthents Pedons 2, 5, 9, 11, 13, 14 and 18 : Fine loamy, mixed, isohyperthermic, Typic Hapustalfs Pedon 8 : Fine loamy, mixed, isohyperthermic, Ultic Haplustalfs Pedon 17 : Coarse loamy, mixed, isohyperthermic, Typic Haplustepts Pedons 19 and 21 : Skeletal, mixed, isohyperthermic, Typic Ustorthents Fifteen (15) soil mapping units at phase level were identified in Varathuru watershed and were mapped into ten (10) soil series. These ten soil series were classified into four land capability sub-classes such as IIIs (VRT3), IVs (VRT2, VRT5, VRT6 and VRT7), IVes (VRT1, VRT4 and VRT8) and VIIes (VRT9 and VRT10). Similarly, the soils of Varathuru watershed were grouped into four land irrigability sub-classes namely, 3s (VRT2 and VRT6), 4s (VRT1, VRT3, VRT4, VRT5, VRT7 and VRT8), 5s (VRT9) and 6s (VRT10). The soil series viz., VRT1, VRT4, VRT5 and VRT8 were moderately suitable (S2) for growing groundnut, redgram and sugarcane and not suitable (N) for growing rice crop whereas the soil series namely VRT2 was marginally suitable (S3) for xviii growing redgram and sugarcane and not suitable (N) for growing groundnut and rice crop. The soil series such as VRT3 was highly suitable (S1) for growing groundnut, moderately suitable (S2) for redgram and sugarcane and not suitable for rice crop. The soil series namely VRT6 was moderately suitable (S2) for growing redgram, marginally suitable (S3) for growing groundnut and sugarcane and not suitable (N) for rice. The soil series of VRT7 was moderately suitable (S2) for growing redgram, marginally suitable (S3) for sugarcane and not suitable (N) for growing groundnut and rice. However, the soil series VRT9 was marginally suitable (S3) for growing redgram and not suitable (N) for growing groundnut, sugarcane and rice crops whereas the soil series of VRT10 was not suitable for growing groundnut, redgram, sugarcane and rice crops Production potential revealed that, actual productivity of soil series were poor, average and good whereas potential productivity of soil series were average, good and excellent. The coefficient of improvement (Ci) varied from 1.43 to 4.46 indicating the implementation of judicious soil and water management practices to sustain soil productivity. Soil fertility maps were also prepared for watershed for various parameters such as pH, EC, organic carbon, available macronutrients (N, P2O5, K2O and S) and micronutrients (Zn, Fe, Cu and Mn) under GIS technology using ArcGIS 10.3 version
Open Access
SYNTHESIS, CHARACTERIZATION AND EVALUATION OF THE EFFICACY OF BIOCHAR BASED NANO-PHOSPHORUS FERTILIZER ON GROUNDNUT PRODUCTIVITY IN ALFISOLS
(Acharya N G Ranga Agricultural University, 2024-05-23) M. KAVITHA; Dr. T.N.V.K.V. PRASAD
The present investigation entitled “Synthesis, characterization and evaluation of the efficacy of biochar based nano-phosphorus fertilizer on groundnut productivity in Alfisols” was carried out involving three experiments during 2020 and 2021 at S.V. Agricultural College, Tirupati campus of Acharya N.G. Ranga Agricultural University of Andhra Pradesh. Nanoscale phosphorus particles were prepared by the biological method by using Stevia leaf extract as reducing and stabilizing agent. Surface modification of biochar was done through acid wash and gum acacia was used as a binding agent for loading of nano-phosphorous particles. The techniques such as, UV-VIS spectroscopy, Fourier transform infrared spectroscopy (FT IR), Dynamic light scattering (DLS), Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to characterize the biochar based phosphorus fertilizer (BBPF), biochar based nano-phosphorus fertilizer (BBNPF) and nano phosphorous (NP). The synthesized BBPF, BBNPF and NP mean size was 110.8, 87.6 and 53.7 nm, respectively. A pot culture experiment was carried out to know the effect of different concentrations of BBPF and BBNPF on groundnut plants. Increased plant height, higher values of dry matter, leaf area, phosphorus content and phosphorus uptake and significantly higher yield parameters (number of pod plant-1 , number of kernels plant-1 , kernel weight plant-1 ) in groundnut were recorded with the application of BBPF and BBNPF. xxi Based on the results obtained from the pot culture experiment, the treatments viz., 100% RDP + BBPF @ 10 kg ha-1 , 75% RDP + BBPF @ 10 kg ha-1 and 75% RDP + BBPF @ 8 kg ha-1 , 100% RDP + BBNPF @ 4 kg ha-1 , 75% RDP + BBNPF @ 4 kg ha-1 and 100% RDP + BBNPF @ 6 kg ha-1 were identified as prominent doses and were taken up for field evaluation. The field experiments were conducted during two seasons viz., kharif 2020-21 and rabi 2020-21 in wetland farm, S.V. Agricultural College, Tirupati. The experiments were laid out in randomized block design (RBD) with three replications and ten treatments (with groundnut cultivar ‘Dharani’). BBPF and BBNPF were applied as per the treatments, while nitrogen and potassium were applied common to all the treatments and gypsum was applied (just before flowering stage) @ 500 kg ha-1 . BBPF and BBNPF levels significantly influenced the growth parameters, yield and yield attributes, phosphorus uptake, and post-harvest soil available phosphorus and overall economic returns of groundnut. Higher leaf area index was recorded with soil application 100% RDP + BBNPF @ 4 kg ha-1 (T7). The next best results were noticed with the 75% RDP + BBNPF @ 4 kg ha-1 (T8). At all the stages of observation, maximum dry matter was recorded with the application of 100% RDP + BBNPF @ 4 kg ha-1 (T7). However, nodule count was not significantly influenced by the treatments at different stages of sampling (30, 60, 90 DAS and harvest) during both seasons of experimentation except at 30 DAS during rabi season. With regard to the yield attributes viz., number of pods plant-1 , 100-pod weight, 100-kernel weight and shelling percentage were higher with the application of 100% RDP + BBNPF @ 4 kg ha-1 (T7). The next best treatment was 75% RDP + BBNPF @ 4 kg ha-1 (T8) and lower number of pods plant-1 , 100-pod weight, 100-kernel weight and shelling percentage of groundnut were recorded with the control, during both the instances of study. The pod yield and haulm yields of groundnut were significantly influenced by the soil application of BBPF and BBNPF. The higher pod yield was recorded with the application of 100% RDP + BBNPF @ 4 kg ha-1 (T7). The haulm yield of groundnut increased significantly with 100% RDP + Soil application of BBNPF @ 4 kg ha-1 (T7) which was however at par with 75% RDP + Soil application of BBNPF @ 4 kg ha-1 (T8) and statistically comparable with 100% RDP + BBPF @ 10 kg ha-1 (T6). Lower pod yield and haulm yields were noticed with the no application of fertilizers (T1). Similar trend was noticed during both the seasons of investigation. Soil application of biochar based phosphorus and nano-phosphorus significantly influenced phosphorus content and phosphorus uptake of groundnut at different stages during both seasons of study. The phosphorus content and phosphorus uptake were higher with the soil application of 100% RDP + BBNPF @ 4 kg ha-1 (T7). The lower phosphorus content and phosphorus uptake by groundnut were recorded with the control (T1). xxii BBPF and BBNPF levels failed to exert significant influence on the post harvest soil physical (soil texture, bulk density, porosity and maximum water holding capacity) and soil physico-chemical (soil pH, EC and OC) properties during both the seasons of study. Post-harvest available nitrogen and phosphorus status (soil) were significantly influenced by the applied levels of BBP and BBNP during both the seasons of the investigation. The higher available nitrogen and phosphorus were recorded with the application of 100% RDP + soil application of BBNPF @ 4 kg ha-1 (T7). The lower levels of available nitrogen and phosphorus were noticed with the control (T1), whereas, the effect on available potassium was not statistically significant by the imposed treatments. Post harvest available secondary (Ca, Mg and S) and micronutrients (Fe, Mn, Cu and Zn) in soil were found to be non-significant with the soil application of BBPF and BBNPF, during both the years of study. Among the different treatments, the higher gross returns, net returns and benefit-cost ratio were realized with the soil application of 100% RDP + BBNPF @ 4 kg ha-1 (T7) which was comparable with 75% RDP + soil application of BBNPF @ 4 kg ha-1 (T8). However, lower economic returns were recorded with the crop that has not received any application of nutrients (T1), during both seasons of experimentation. In conclusion, the results of the present study revealed that the soil application of 100% RDP + BBNPF @ 4 kg ha-1 recorded higher pod yield and economic returns in groundnut grown in red sandy loam soils. Further, loading of nano-phosphorus with biochar and the consequent application to the soil enhance the phosphorus availability with an extended period of time due to slow-release activity and thereby sustain the groundnut productivity
Open Access
CHARACTERIZATION, CLASSIFICATION AND EVALUATION OF SOILS OF PALAMANER DIVISION IN CHITTOOR DISTRICT OF ANDHRA PRADESH FOR SUSTAINABLE LAND USE PLANNING
(Acharya N G Ranga Agricultural University, 2024-05-23) B. JAYASREE; Dr. M.V.S. NAIDU
The present investigation entitled "Characterization, classification, and evaluation of soils of Palamaner division in Chittoor district of Andhra Pradesh for sustainable land use planning," involved 18 master profiles in three transects with 6 pedons each. The morphological, physical, physico-chemical, chemical, elemental composition, and available and total macro and micronutrients of these pedons were examined. The study area had a semi-arid monsoonic environment with distinct summer, winter, and rainy seasons. The three transects that make up the Palamaner division's research area are transect-I, transect-II and transect-III. Pedons 1 and 2 were situated on top slopes (3-5%), pedons 3 and 4 on middle slopes (1-3%), and pedons 5 and 6 on lower slopes (0-1%) in transect-I. In a similar fashion, in transect -II, pedons 7 and 8 were found on upper slopes (3-5%), pedons 9 and 10 on middle slopes (1-3%), and pedons 11 and 12 on lower slopes (0-1%). In contrast, pedons 13 and 14 in transect III were situated on higher slopes (5–10%), pedons 15 and 16 in the centre of the slope range (3-5%), and pedons 17 and 18 in the lower slope range (1-3%). According to 30 years of meteorological data, the distribution of rainfall was essentially symmetric. Rainfall has strong abnormalities, which symbolises the dry land agriculture in the research region, according to the precipitation concentration index (PCI), which was determined. The seasonality index was above 1.2 in some years, indicating that the study area's rainfall was cyclical with brief dry seasons. The research region comes under the isohyperthermic soil temperature regime and ustic soil moisture regime based on mean air and soil temperatures, with a growing season of 90 to 150 days, supporting a single crop. xxiii The morphological characteristics of the soils (Transect-I) revealed that the upper slopes (Kanalillu, P1 and Kummaragunta, P2) had Ap-Bw and Ap-Bt horizons, while the middle slopes (Chellargunta, P3 and Settipalle, P4) include Ap-AC and Ap-Bt horizon sequences, and the lower slopes' soils display Ap-Bt and Ap-B/A-BA-Bt horizon sequences (Gorreladoddi P5, Chinnapuram P6). These soils have a matrix that ranges from extremely light brown (2.5 YR 8/3) to dark reddish brown (2.5 YR 3/4), however they were sandy loam to clay loam texture. Transect-II soils were made up of Atukurallapalle (P7) and Samalagadda (P8) on the upper slopes, Gangavaram (P9) and Kongavaripalli (P10) on the middle slopes, Maredupalli (P11) and Jidimakulapalli (P12) on the lower slopes. The soils on the upper slopes have horizon sequences of Ap-BA-Bt and Ap-A/B-B/A-Bw1- Bss1, respectively, while the soils on the lower slopes have horizon sequences of Ap-AB-Bw and Ap-Bw1-Bw2-Bw3-Bw4, and the soils on the middle slopes have Ap-Bt1-C1-2Bt1 and Ap-Bt1-C1-Bt2. The soils are fairly deep to deep, sandy loam to clay loam in texture, and dark reddish brown (2.5 YR 3/4) to light grey (10YR 7/2) in colour. Transect-III soils included Zararipalli (P13), Kilapatla (P14), Gandhinagar (P15), Mogili (P16), Gourishankarapuram (P17), and Mittur (P18), and the pedons showed Ap-Bt horizon sequences. These soils were loamy sand to clay texture with a dark reddish brown (2.5 YR 3/4) to light brown (7.5 YR 6/4) matrix. All of the pedons in transect-I have more sand in the top soil, whereas the deeper layers have more silt and clay. Subsoil layers that had a sand to silt ratio of less than 1 showed discontinuities that were similar to those found in field descriptions as well as abrupt shifts like those seen in P1, P4, and P5. P9 and P10, which have comparable horizon sequences in the soils of transect-II and referred to as the C1 horizon features abrupt sandy loam horizons interspersed with sandy clay loam horizons. Sand, silt and clay were present in nearly equal amounts on the upper and lower slopes of the soils of transect-III. In transects I, II, and III, the mean bulk densities of the soils were 1.43 Mg m-3 , 1.45 Mg m-3 , and 1.48 Mg m-3 , respectively. The soils' clay content and water holding capacity tended to expand in comparable ways. The soils of transects I, II and III were low to medium in organic carbon, non-saline, and mildly acidic to neutral. The soils had a C:N ratio that ranged from 4.21 to 11.29 and a CEC of 5.23 to 46.23 cmol (p+) kg-1 . The soils were predominately composed of exchangeable Ca and exchangeable bases were in the order of Ca > Mg > K > Na. Regardless of the slopes and transects, the overall nitrogen content was less than 1 per cent. The total phosphorus concentration ranged from 184 to 745 mg kg-1 , the total potassium ranged from 2000 to 5167 mg kg-1 , and the total sulphur ranged from 200 to 960 mg kg-1 in the soils. The total zinc level in the soils ranged from 18.24 to 60.22 mg kg-1 , whereas the total copper content ranged from 17.06 to 52.75 mg kg-1 , the total manganese content from 112.64 to 386.26 mg kg-1 , and the total iron from 0.87 to 6.47 mg kg-1 . However, the soils of transects-I, II and III have low to medium levels of accessible N, high to medium levels of available P and low to medium/high levels of available K and deficient to sufficient in available S. DTPA extractable Cu and Mn were sufficient whereas, the DTPA extractable iron and zinc were deficient to sufficient irrespective of slopes and transects. xxiv Molar ratios and weathering indices were developed from the bulk geochemical data to comprehend the weathering patterns of these soils. All of the transects' predominant elemental compositions were SiO2, Al2O3, and Fe2O3. P2O5, K2O, and Na2O concentrations in all of the soils were less than 1 per cent. The concentrations of CaO and MgO ranged from 0.82 to 2.67 and 0.22 to 1.62, respectively. Clayeness (mAl2O3 / mSiO2) and calcification index (CaO + MgO / Al2O3) were found as two prominent pedogenic processes using molar ratios. The research area's soils were moderately to extremely worn, according to the CIA index of soils, which ranged from 74.95 to 87.70 per cent. The soils' Index-A and B values ranged from 0.82 to 0.91 and 0.11 to 0.21, respectively, while the CIA-K and WI (weathering index) values ranged from 76.58 to 89.31 and 2.35 to 4.05, respectively. The A-CN-K diagram revealed that granite-gneiss samples were situated above the K-feldspar join, in the centre of the A-K and A-CN lines. This tendency might be brought on by the removal of Ca and Na through plagioclase degradation. Illite formation is further aided by the transition of K-feldspar and illite when kaolinite has not yet formed. The retention of Fe(t) and Mg as weathering continues is likewise depicted in the A-CNK-FM graphic. Pedon 3 : Coarse – loamy, mixed, isohyperthermic, Typic Ustorthents Pedons 1, 8 and 11 : Fine – loamy, mixed, isohyperthermic, Typic Haplustepts Pedon 12 : Fine, mixed, isohyperthermic, Vertic Haplustepts Pedons 2, 4, 5, 6, 9, 10, 13, 14, 15, 16 and 17 : Fine – loamy, mixed, isohyperthermic, Typic Haplustalfs Pedon 7 : Fine – loamy, mixed, isohyperthermic, Typic Rhodustalfs Pedon 18 : Fine – loamy, mixed, isohyperthermic, Ultic Haplustalfs The soils of the study area were divided into land capability subclasses viz., IIIs (pedon 6), IIIes (pedon 3, 15 and 18), IVs (pedons 4, 5, 9, 10, 11 and 12), IVes (pedons 1, 2, 7, 8, 13, 14 and 16), and VIes (pedon 17). The study area's soils have been divided into four land irrigability sub-classes such as, 2s (pedon 18), 3s (pedons 2, 3, 4, 5, 6, 10 and 15), 4s (pedons 1, 7, 8, 9, 11, 12, 13, 14 and 16), and 6s (pedon 17). According to the evaluation of the soil-site suitability in the research region, pedons 1, 2, 3, 4, 5, 6, 10, 13, 14, 15, 16, 17 and 18 were not appropriate (N) for rice, marginally suitable (S3) for groundnut and moderately suitable (S2) for maize and finger millet. While pedons 7, 8, 9, and 11 were only moderately suitable (S2) for maize and finger millet, pedons 7, 8 and 12 were only marginally acceptable (S3) for groundnut. Pedon 12 was also only moderately suitable (S2) for rice, groundnut and finger millet. The potential productivity of soils was good to exceptional for most pedons, while actual soil productivity ranged from ordinary to good. The crop improvement factor varied from 1.43 to 1.58, demonstrating the use of wise soil and water management techniques to maintain soil productivity
Open Access
DELINEATION AND MAPPING OF SOIL CONSTRAINTS AND THEIR EFFECTS ON YIELD AND QUALITY OF MANGO (Mangifera indica L.) IN YSR DISTRICT, ANDHRA PRADESH USING REMOTE SENSING AND GEOGRAPHIC INFORMATION SYSTEM
(Acharya N G Ranga Agricultural University, 2024-05-22) M. BALAKRISHNA; Dr. T. GIRIDHARA KRISHNA
The present study on “Delineation and mapping of soil constraints and their effects on yield and quality of mango (Mangifera indica L.) in YSR district, Andhra Pradesh using remote sensing and geographic information system” was undertaken to identify the soil related constraints and delineate the spatial variability of soil fertility status in order to suggest fertilizer recommendation in YSR district of Andhra Pradesh using remote sensing and GIS techniques. Georeferenced samples (250 Nos) were collected from the study area following spatially balanced sampling technique. The soil samples were analyzed for physical properties like texture, colour, bulk density, particle density, percent pore space and water holding capacity, physico-chemical properties viz., pH, EC, OC, CEC, and free CaCO3 and chemical properties viz., available N, P, K, Ca, Mg, S, Fe, Mn, Zn and Cu. Similarly, leaf samples were analyzed for total N, P, K, Ca, Mg, S, Fe, Mn, Zn and Cu and fruit samples were analyzed for per cent juice, juice pH, TSS and vitamin-C. In irrigation water, quality parameters such as pH, EC, cations viz., Na+ , Ca2+, Mg2+, K+ and anions viz., CO3 2- , HCO3 - , Cl- , SO4 2- , RSC and SAR were analyzed. Sixteen pedons were selected based on the total area of mango grown in each mandal and were studied for soil properties to know constraints in sub surface layers of soils. xvi The various soil textural classes identified in surface soils were 42.80 per cent was sandy loam, 38.00 per cent was sandy clay loam, 12.40 per cent was loamy sand, 4.4 per cent was sandy clay and 2.40 per cent was clay loam. Texture of surface horizons and sub-surface horizons in pedons varied from sandy loam to sandy clay loam and gravel nature was seen in subsurface layers of some of the mandals. The colour of the soils in the study area had their Munsell colour notation in the hue of 10 YR / 7.5 YR / 5 YR / 2.5 YR with value of 3 to 6 and chroma of 2 to 8. The colour in all pedons varied from very dark red to dark greyish brown with a hue ranged from 2.5 YR to 10 YR, value ranged from 3 to 6 and chroma varied between 1 and 8. The pH of the study area was neutral to moderately alkaline in reaction. Out of total study area 38.80 per cent was neutral, 41.20 per cent was weakly alkaline, 19.20 per cent was moderately alkaline and 0.80 per cent was strongly alkaline in soil reaction. All the pedons of the study area were neutral to moderately alkaline in reaction. The orchard soils were non-saline in nature as the EC of these soils was far below 1.0 dS m-1 . The study area soils were low to medium in organic carbon at surface and low in sub-surface layers. The organic carbon content decreased with increasing depth. Out of all the surface soils of mango orchards studied, 80.00 per cent were low in available N and 20.00 per cent were medium in available N, 5.60 per cent were low in available P, 92.00 per cent were medium in P and 2.40 per cent were high in P. However, about 32.00 per cent were low in available K, 35.20 per cent were in medium range and 32.80 per cent were in high range. The higher exchangeable calcium and magnesium status was observed in all the orchards. In pedons the available nitrogen was ranged from 59.79 to 273.12 kg ha-1 and were low in available nitrogen. The available nitrogen was significantly and positively correlated (r = +0.514**) with organic carbon. The available phosphorus varied from 5.05 to 45.05 kg ha-1 . All the pedons showed a decreasing trend with depth. The available potassium in different pedons ranged from 49.98 to 512.05 kg ha-1 soil. The lowest value of 49.98 kg ha-1 was observed in pedon 10 and the highest was 512.05 kg ha-1 . Calcium, magnesium and sulphur contents recorded sufficient in all the villages of twelve mandals. All pedons showed an increasing trend with depth for exchangeable calcium and magnesium whereas deceasing trend with available sulphur and available micronutrients. The data on micronutrient status in these twelve mandals of the study area revealed that copper and manganese content in almost all soils was sufficient whereas iron (50%) and zinc content (48%) was deficient in the soils of Veeraballi and T. Sundupalle mandals. Two per cent of the leaf samples were deficient in N, 8 per cent deficient in P and 4 per cent deficit in K. N, P, K, Ca and Mg were 42, 12, 14, 2 and 12 per cent low in leaf samples, respectively while N, P, K, Ca and Mg were 4, 50, 16, 18 and 18 per cent were high in leaf samples, respectively. Zn deficiency in xvii leaf was the most severe among the 10 mineral elements tested and 90 per cent of samples were deficient in Zn, followed by Fe (64%), Mn (36%) and Cu (25%). However, the average leaf content of N, P, Ca and Cu was 1.27, 0.12, 2.39 and 8.9 per cent, respectively, which was within the optimum range. The correlation between fruit yield, soil pH and CaCO3 in soil was found to be negative and significant whereas the correlation between fruit yield and soil EC was found to be negative and non-significant Fruit yield was positively and significantly influenced by soil organic carbon content (r = 0.360), because the organic carbon content of the soil had a significant positive influence on soil N (r = 0.716**). The soil mineral nutrients like N, P and K influenced the fruit weight significantly and positively (r = 0.469*, r = 0.446* and r = 0.415*, respectively). Fruit juice per cent had significant and positive relation with soil N (r = 0.353*) and P (r = 0.364*). Soil P had a significant and positive correlation with TSS (r = 0.438*). The pH of the irrigation water samples collected from mango orchards of study area varied from neutral (6.77) to mildly alkaline (8.05). The EC of the irrigation water varied from 0.82 - 3.87 dS m-1 with a mean value of 1.82 dS m-1 . According to the irrigation water EC classification, 76 per cent of the water samples were high in salinity with C3 class and 24 per cent of the water samples were categorized with high salinity (C4 class). The concentration of major anions of irrigation water collected from all the mango orchards were in the order of HCO3 - > Cl- > SO4 2- > CO3 2- and the cations were in the order of Na+ > Mg2+ > Ca2+ > K+ . The general constraints that were observed in the soils of mango orchards were low organic carbon, low to medium available nitrogen and phosphorus, wide spread deficiency of zinc and iron, low to medium Mn, wide occurrence of soil alkalinity, calcareousness and poor quality of irrigation water i.e., high to very high salinity of the irrigation water. Soil nutrients thematic maps were prepared using remote sensing and GIS techniques and delineated the soil related constraints. On the basis of fertility mapping, suitable recommendations were made in the study area in terms of available nutrients. In conclusion, it can be summarized that the new technologies such as remote sensing, GIS and GPS have opened a new era in generating natural resource database to integrate and assess their potential on spatial basis. Integration of GIS in the present study was highly useful in identification of soil related constraints spatially and in generating the fertilizer recommendation maps and soil suitability assessment. Also, by identifying the soil related constraints in the study area, it made clear that there is a need of adoption of soil test crop response based integrated plant nutrition system (STCR-IPNS) and micronutrient recommendations to mango would enhance the crop productivity, fertilizer use efficiency and alleviate the deficiencies over long run
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.

Acharya N G Ranga Agricultural University, Guntur

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