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    ThesisItemOpen Access
    EVALUATION OF DAMAGE CAUSED BY ROOT KNOT NEMATODE AND ITS SURVIVAL IN TUBEROSE DURING STORAGE OF BULB
    (2023) Arandhara, Babyshree; Gogoi, B. B.
    In the present investigation on evaluation of damage caused by root knot nematode and its survival in tuberose during storage of bulbs, it was observed that all growth parameters of tuberose were affected with corresponding increase in inoculum levels. Plant showed gradual increase in number of galls, egg masses and final nematode population in the soil with increase in population levels of root knot nematode from 20 to 10,000 nematode per pot. Reproductive rate was found to be maximum at lowest inoculum and minimum at highest inoculum of 10,000 M. incognita per kg soil. In the investigation on survival of root knot nematode during storage of bulb, the study of stored planting material (bulbs of tuberose) reveled that all the stages of root knot nematode were present within the bulbs. J2 were found within the bulb and also in between the layers of bulbs. J3, J4 and adult females were found in the bulb tissue. Some adults were also found to be aggregate in between the layers of bulb tissue. There was a reduction in nematode population (56.91%) during the storage period of 6 months. Egg masses within the bulb were brownish in colours, protected by gelatinous matrix and the bulb tissue. The egg masses attached to the basal portion of the bulbs were deep orange colour. The change in colour of egg masses attached to the basal portion of the bulbs during the storage period might be due to drying and tanning of the gelatinous matrix may be due to low moisture for an extended period of time. Germination percentage of the stored bulb was recorded to be 70%. There was 30% reduction in germination of stored bulb due to heavy nematode infestation and drying of bulbs in storage. When infected stored bulbs were replanted in pots with sterilized soil, survival and transmission of nematode to the new crop was confirmed by the developed symptoms (gall and egg mass formation) on roots.
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    ThesisItemOpen Access
    EXPLORATION AND EVALUATION OF BIOPROTECTIVE RHIZOSPHERIC MICROORGANISMS AGAINST MELOIDOGYNE GRAMINICOLA
    (2022) Jena, Rupak; Choudhury, B. N.
    Eighteen bacterial strains and eleven fungal strains were isolated from rhizosphere of different crops like rice, okra, ash gourd, chili, beans, cucumber from diverse conditions and soil types in and around Jorhat. The biochemical characterization of the isolated bacterial strains disclosed that six bacterial isolates tested negative for KOH test while twelve tested positive. All the bacterial strains exhibited positivity for gelatin hydrolysis and catalase test. Seven bacteria showed positive while eleven showed negative reaction to citrate test. Morphological findings stated that six bacterial strains were gram positive while twelve stained negatively, fifteen bacteria were rod shaped, two were coccus and one diplococcus in shape and all the bacterial isolates exhibited motility. The study of in vitro efficacy of the twenty nine bacterial and fungal isolates tested against second stage juveniles of M. graminicola revealed that all the bacterial and fungal isolates potentially impacted the test organism and caused significant mortality over sterile water treatment. The promising bacterial and fungal isolates were identified as BSH8, BTS4, BTS5, BJA15, FJB 11 and FSH5. The best result on mortality was exhibited by BSH8 with 80.79% mortality over J2 of M. graminicola. The effective and promising bio agents were identified using the 16 S rRNA sequencing and the organisms were Bacillis subtils (BSH8), Bacillus velezensis (BTS4), Alcaligenes faecalis (BTS5), Rhizobium pusense (BJA15), Talaromyces allahabadensis (FSH5) and Trichoderma asperellum (FJB11). In the pot experiment seventeen treatments were formulated using five potential isolates (3 bacteria, 2 fungi) either alone or in various compatible combinations. All the treatments showed significant results over the untreated control. The isolates improved the overall plant biomass and reduced the nematode reproduction and final population over control. The combined application of B. subtilis as seedling root dip + B. velezensis as soil treatment + T. asperellum as soil treatment @ 1x108 cfu/ml exhibited the maximum impact on plant morphological parameters viz., root length, shoot length, fresh and dry weight of root and shoot and inhibited the nematode population by decreasing the number of galls, egg masses and eggs/egg masses. The next best treatment was seedling root dip with B. subtilis+ soil treatment with T. asperellum and seedling root dip with B. velezensis + soil treatment with T. asperellum @ 1x108 cfu/ml.
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    ThesisItemOpen Access
    Biomanagement of disease complex of Meloidogyne incognita and Fusarium oxysporum f.sp ciceri on chickpea (Cicer arientinum., Butler 1918)
    (2021) Roy, Pallabi; Borah, A.
    In the present study on the interaction of Meloidogyne incognita and Fusarium oxysporum f.sp ciceri on chickpea, the result indicated that dual inoculation treatments significantly decreased plant growth parameters over the treatment with M. incognita @1000 J2/kg soil and F. oxysporum @ 2% (w/w). The treatment with M. incognita @1000 J2/kg soil + F. oxysporum @ 2% (w/w) after 15 days of inoculation was statistically superior in decreasing the plant growth parameters of chickpea. However, number of galls, eggmasses, final nematode population was found maximum in single inoculation treatment than dual inoculation treatments. The highest number of galls, eggmasses, final nematode population were observed in the treatment with M. incognita @1000 J2/kg soil. The maximum disease incidence was recorded in the treatment with M. incognita @1000 J2/kg soil and F. oxysporum @ 2% (w/w) after 15 days of inoculation. Studies on the management of disease complex of Meloidogyne incognita and Fusarium oxysporum on chickpea with microbial consortia, vermicompost and Glomus fasiculatum alone or in combination under microplot condition showed that all the treatments differed significantly over untreated control in respect of increaseing plant growth parameters and yield of chickpea. The seed treatment with microbial consortia @ 5ml/l + soil application of vermicompost enriched microbial consortia @ 2t/ha + seed treatment with microbial consortia @ 5ml/l + soil application of Glomus fasciculatum spores/m2 was found to be most effective in increasing plant growth parameters, yield, N,P, and K content in soil. All the treatment significantly decreased the number of galls, eggmasses, nematode population and fungal population in soil and percent disease incidence. In the pilot field trial, conducted at farmers field with the best treatment combination found under microplot trial for the management of disease complex of Meloidogyne incognita and Fusarium oxysporum on chickpea showed that the seed treatment with microbial consortia @ 5ml/l + soil application of vermicompost enriched microbial consortia @ 2t/ha + seed treatment with microbial consortia @ 5ml/l + soil application of Glomus fasciculatum spores/m2 effective in increasing plant growth characters, yield and reducing in number of galls, final nematode population in soil and percent disease incidence over untreated control.
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    ThesisItemOpen Access
    GRAFTING FOR THE MANAGEMENT OF ROOT KNOT NEMATODE, Meloidogyne incognita IN BRINJAL
    (AAU, Jorhat, 2021) Prasanth, Polimera; Bhagawati, B.
    An attempt was made for the management of root knot nematode, Meloidogyne incognitain brinjal through grafting. Thirteen Solanum species were screened against M. incognita. Of these, S. torvum and S. khasianum showed resistant and moderately resistant reactions against M. incognita and remaining species showed highly susceptible reactions against M. incognita. S. torvum and S. khasianum were taken as rootstocks. Liliya and Kokila were taken as scions. Highly susceptible and cultivated hybrids, Liliya and Kokila were grafted on resistant rootstock S. torvum and onmoderately resistant rootstock S. khasianum. Cleft graftingmethod was adopted for grafting. The highest success rate of grafting was recorded on S. torvum× Liliya, followed by S. torvum× Kokila. Liliya and Kokila grafted on S. torvum showed maximum reduction in number of galls, egg masses per root system, final nematode population and rate of reproduction with increased number of fruits per plant, fruit weight, fruit yield per plot and total fruit yield per ha followed by Liliya and Kokila grafted on S. khasianum. Delayed flowering and fruiting was observed in grafted plants as compared to non grafted plants.
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    ThesisItemOpen Access
    Approaches for management of Meloidogyne incognita in Pulse crops
    (AAU, Jorhat, 2022) Zonunpuii, Maria; Das, Debanand
    Investigation were carried out under Net House condition to evaluate the reaction of eight chickpea germplasm, ten pea germplasm and forty six lentil germplasm along with their respective susceptible checks for resistance against Meloidogyne incognita. All eight germplasm of chickpea screened were found to be either susceptible or highly susceptible to M. incognita. None of the germplasm were found to be resistant to M. incognita. Among ten germplasm of pea, two germplasm viz., IPFD-99-13 and IPFD-12-2 were found to be resistant, two germplasm were found to be moderately resistant, and the rest six germplasm were found to be either susceptible or highly susceptible. Out of forty six lentil germplasm screened, only one germplasm (IPL 81) was found to be resistant, seven germplasm were found to be moderately resistant, while the rest thirty eight germplasm were found to be either susceptible or highly susceptible to M. incognita. Study on the bio-intensive management of M. incognita on black gram with bio-agents viz., Bacillus marisflavi, Bacillus altitudinis, Bacillus subtilis, Trichoderma viride, Verticillium lecanii and Pseudomonas fluorescens showed significant increase in plant growth parameters including root nodulation with corresponding decrease in number of galls per root system, egg masses per root system, and final nematode population over untreated control. The treatment with soil application of Pseudomonas fluorescens @ 1x108 cfu/ml enriched in vermicompost @ 20 g/m2 was found to be the most effective in enhancing plant growth parameters, number of nodules per root system and reducing number of galls per root system, egg masses per root system and final root-knot nematode population in soil. Nonetheless, all the treatments significantly decreased number of galls, egg masses and final nematode population in soil.
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    ThesisItemOpen Access
    ISOLATION AND FORMULATION OF ENTOMOPATHOGENIC NEMATODES
    (AAU, Jorhat, 2018) GEORGE, JISNA; Devi, Gitanjali
    An experiment entitled “Isolation and formulation of Entomopathogenic nematodes” was conducted in the laboratory of Department of Nematology, Assam Agricultural University, Jorhat. A random survey was conducted for the natural occurrence of EPNs during 2016-17 from vegetable growing areas. A total of two hundred soil samples were collected from ICR Farm, Experimental farm of Department of Horticulture and Hostel areas, AAU, Jorhat and Allengmora, Jorhat. Survey data revealed that out of 200 soil samples, twelve samples were positive for EPNs with six samples containing Oscheius (3%), five samples containing Heterorhabditis (2.5%) and one sample containing Steinernema (0.5%). Oscheius isolates were designated as EPN-O-J-1, EPN-O-J-2, EPN-O-J-3 and Heterorhabditid isolate designated as EPN-H-J-1, EPN-H-J-2 were found from rhizosphere of chilli, cowpea, bhendi, brinjal and chilli respectively from ICR Farm, AAU, Jorhat. Another isolate of Oscheius designated as EPN-O-J-4, EPN-O-J-5 and Heterorhabditid isolate designated as EPN-H-J-3, EPN-H-J-4, EPN-H-J-5 were found from rhizosphere of bhendi, chilli, cucumber and bhendi respectively from Hostel areas, AAU, Jorhat. One Oscheius isolate designated as EPN-O-J-6 was found from rhizosphere of pumpkin and one steinernematid isolate designated as EPN-S-J-1 was found from rhizosphere of ivy gourd from Allengmora, Jorhat. Morphological and morphometrical characters were used in the identification of nematode isolates. The identified species were Heterorhabditis bacteriophora, Oscheius rugaoensis and Steinernema kushidai. O. rugaoensis was the predominant species followed by H. bacteriophora and S. kushidai. Nematode survival within each formulation was determined after one week up to 6th week. Formulations were stored at 5°C and 300C. Storage stability in all formulations decreased during the storage period. Per cent survival of H. bacteriophora infective juveniles (IJs) was 99.80% in alginate gel, and 98.36% in sawdust during 6th week of storage at 50C, whereas per cent survival was less (98.90% and 98.36% respectively) at 300C up to 6th week of storage. O. rugaoensis showed 98.30% survival in sawdust and 97.30% survival in alginate gel formulation at 50C, whereas per cent survival was less (95.50% and 93.76%, respectively). Per cent survival of S. kushidai infective juveniles (IJs) was 95.56% in alginate gel, and 93.73% in sawdust, respectively during 6th week of storage at 50C, whereas per cent survival was less (93.80% and 91.53%, respectively) at 300C. The quality control measure implemented to determine the virulence of formulated nematodes, using the percentage mortality of G. mellonella as an indicator, was effective. Per cent infectivity to G. mellonella larva was more in H. bacteriophora (93.66%) in alginate gel formulation followed by O. rugaoensis (93.33%) in sawdust formulation and S. kushidai (91.00%) in alginate gel formulation in both bioassay.
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    ThesisItemOpen Access
    Pathogenicity and Management of Root-knot Nematode (Meloidogyne incognita) on Ivy gourd (Coccinia indica L.)
    (AAU, Jorhat, 2018) Sonowal, Bidisha; Mahanta, B.
    In the present study on pathogenicity of Meloidogyne incognita on Ivy gourd showed that there was a progressive decrease in the growth of Ivy gourd plants as the inoculum level of Meloidogyne incognita increased. An initial inoculum level of 100 juveniles per pot caused significant reduction in plant height, shoot weight and root weight and proved to be pathogenic to Ivy gourd plants. The reproductive rate of nematode was maximum at the initial inoculum level of 10 juveniles per pot and minimum at the highest inoculum level of 10,000 juveniles per pot. Studies on the efficacy of Glomus fasciculatum, Org-Trichojal, vermicompost and carbofuran 3G in the management of Meloidogyne incognita on Ivy gourd under field condition showed that all the treatments were effective in increasing plant growth parameters and yield of Ivy gourd. All the treatments significantly decreased root-knot index and final nematode population in soil. The treatment with Glomus fasciculatum @ 300 spores/ m2 + Org-Trichojal @ 1 l/ha + vermicompost @ 1.25 t/ha was found to be effective in increasing the plant growth parameters and yield of Ivy gourd per plot. The treatment with carbofuran 3G @ 1 kg a.i/ha was found to be effective in suppressing the root-knot index and final nematode population in soil.
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    ThesisItemOpen Access
    HISTOPATHOLOGICAL AND BIOCHEMICAL CHANGES IN TRADITIONAL RICE CULTIVARS DUE TO RICE ROOT-KNOT NEMATODE, Meloidogyne graminicola
    (2019-11) Gogoi, Priyanka; Borgohain, N.
    An investigation was carried out to observe the histopathological and biochemical changes in traditional rice cultivars of Assam. A total of 35 rice cultivars were screened against rice root-knot nematode Meloidogyne graminicola. Out of these, eight cultivars viz., Bongal ahu, Malbhog ahu, Naga ahu, Bahadur sub-1, Shraboni, Disang, Kolong and Jaymati were found to be resistant whereas five cultivars viz., Ahu joha, Bhogali bora, Aghoni bora, Ranjit sub-1 and Kanaklata found to be moderately resistant. The two traditional cultivars viz., Sambha mashuri and Kanaklata were found to be susceptible and the remaining 20 cultivars were found to be highly susceptible. Histopathological studies of resistant cultivars revealed that there is no establishment of feeding cells with hypersensitive like reaction in pericycle areas, whereas in susceptible cultivars multinucleate giant cells with dense cytoplasm and large number of vacuole were observed. The hypertrophied and hyperplasia cell were observed surrounding the body of the nematodes and the giant cells were observed at little distance to the nematode head. While evaluating the chlorophyll content, the highest chlorophyll was found in the cultivar Naga ahu i.e 0.040 μg/ml and lowest in Dhanshree. Similarly lowest phenolic content (0.0004 mg/ml) was recorded in the cultivar Sambha mashuri and the highest in Disang and Jaymati (0.00041 mg/ml). The enzymatic activity of PPO was maximum (0.294 mg/min) in cultivar Jaymati and minimum (0.140 mg/min) in Sambha mashuri at 3min time interval. The activity of PAL was highest in the Malbhog ahu (1.57 m-1 mg-1 protein) followed by Bahadur sub-1 (1.51 m-1 mg-1 protein) and minimum in Sambha mashuri (0.16 m-1 mg-1 protein).
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    ThesisItemOpen Access