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Open 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.
Open 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.
Open 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).
Open Access
EFFICACY OF SILVER NANOPARTICLES ON THE MANAGEMENT OF ROOT-KNOT NEMATODE, Meloidogyne incognita IN GREENGRAM
(AAU, Jorhat, 2017-07) Kumari, Suman; Mahanta, Bornali
Open Access
IDENTIFICATION AND MASS PRODUCTION OF ENTOMOPATHOGENIC NEMATODES
(AAU, Jorhat, 2017-07) KALITA, RINKI MANI
An experiment entitled “Identification and mass production of entomopathogenic nematodes” was conducted in the laboratory of Department of Nematology, Assam Agricultural University, Jorhat. A systematic survey was undertaken in Assam Agricultural University, Jorhat Campus for the occurrence of entomopathogenic nematodes during the year 2015-16. A total of 200 soil samples were collected randomly during the period November, 2015 to March, 2016 from four habitats (vegetation type) viz., Instructional-cum-Research (ICR) Farm, Experimental farm of Department of Horticulture, Experimental farm for plantation crops and Fallow land. From each habitat 50 numbers of samples were collected. Survey data revealed that out of 200 soil samples, eight samples were positive for entomopathogenic nematodes (4%), with containing 4 isolates were assigned the genus Steinernema (2%), 2 isolates were assigned to the genus Heterorhabditis (1%) and 2 isolates were assigned to the genus Oscheius (1%). Steinernematid isolates were designated as EPN-S-J-1, EPN-S-J-2, EPN-S-J-3. The isolates were found from rhizosphere of mung bean, arahar and cowpea respectively from ICR Farm, AAU, Jorhat. Another isolate of steinernematid (designated as EPN-S-J-4) was found from rhizosphere of citrus from the Experimental farm of the Department of Horticulture. One heterorhabditid isolate (designated as EPN-H-J-1) was found from rhizosphere of citrus and one isolate of Oscheius (designated as EPN-O-J-1) was found from rhizosphere of coconut in the Experimental farm of the Department of Horticulture. One heterorhabditid isolate (designated as EPN-H-J-2) and another isolate of Oscheius (designated as EPN-O-J-2) were found from tea garden of Experimental farm for plantation crops of AAU, Jorhat. Entomopathogenic nematodes were not recovered from the fallow land. EPN species were identified as Heterorhabditis bacteriophora, Steinernema aciari, Oscheius chongmingensis based on their morphological and morphometrical study of different life stages (infective juveniles, adults of both generations). The mass multiplication of three isolates Heterorhabditis bacteriophora, Steinernema aciari, Oscheius chongmingensis were done on different artificial media (plant and animal origin media). In plant origin media consisted of nine treatments including a control with three replications were laid out in a Completely Randomized Designs. The treatments were T1 (Wheat flour and sunflower oil), T2 (Wheat flour and soya oil), T3 (Wheat flour and coconut oil), T4 (Soya flour and sunflower oil), T5 (Soya flour and soya oil), T6 (Soya flour and coconut oil), T7 (Green gram flour and sunflower oil), T8 (Green gram flour and soya oil), T9 (Green gram flour and coconut oil) and control (Soya flour and corn oil). Among these treatments, T9 containing green gram flour and coconut oil which was found to be highest multiplication rate in all EPN specis viz., Heterorhabditis bacteriophora, Steinernema aciari, Oscheius chongmingensis 97.92 x 105, 114.17 x 105, 104.10 x 105 IJs/flask, respectively. Out of these EPNs spp. Steinernema aciari was found to be more yield (114.17x105) in T9. The medium containing wheat flour and sunflower oil (T1) recorded lowest multiplication rate for Oscheius chongmingensis (3.68 x105) and the medium containing wheat flour, soya oil (T2) recorded lowest multiplication rate for Heterorhabditis bacteriophora (5.19x105) and Steinernema aciari (2.67 x105). In animal origin media comprising of varied sources of proteins and lipids of animal origin and consisted of three treatments including a control with five replications were laid out in a Completely Randomized Designs. Treatments were T1 (Dog biscuit), T2 (Goat waste homogenate), T3 (Pork homogenate) and control (Chicken offal homogenate). Among these treatment, T3 containing pork homogenate which was found to be highest yield in three isolates viz., Heterorhabditis bacteriophora, Steinernema aciari, Oscheius chongmingensis were 6.54x105, 17.24x105, 5.99x105 IJs/100 flask respectively and more yield was found Steinernema aciari. T2 containing goat waste homogenate recorded the least multiplication rate of all three isolates viz., Heterorhabditis bacteriophora, Steinernema aciari, Oscheius chongmingensis were 3.67x105, 6.75x105, 3.47x105 IJs/100 flask, respectively.
Open Access
INTEGRATED MANAGEMENT OF Meloidogyne incognita AND Sclerotinia sclerotiorum DISEASE COMPLEX ON FRENCH BEAN (Phaseolus vulgaris L.)
(AAU, Jorhat, 2017-07) Dutta, Ananya; Borah, A.
In the present study on the interaction of Meloidogyne incognita and Sclerotinia sclerotiorum on French bean, the results indicated that the dual inoculation treatments significantly decreased plant growth parameters over the treatments with S. sclerotiorum @ 0.2% w/w and M. incognita @ 1000 J2/kg of soil. The treatment with M. incognita @ 1000 J2/kg of soil and S. sclerotiorum @ 0.2 % w/w simultaneous inoculation was statistically superior in decreasing the plant growth parameters of French bean. However, the number of galls, eggmasses and final nematode population in soil were found maximum in single inoculation treatment than dual inoculation treatments. The highest number of galls, eggmasses and nematode population were observed in the treatment with M. incognita @ 1000 J2/kg of soil. Maximum disease incidence was recorded in the treatment with M. incognita @ 1000 J2/kg soil + S. sclerotiorum @ 0.2% w/w after 15 days inoculation. Studies on the efficacy of biocontrol agent and chemicals against M. incognita and S. sclerotiorum disease complex on French bean under net house condition showed that all the treatments differed significantly over control in respect of increasing plant growth parameters. The seed treatments with T. harzianum @ 5ml/ kg + seed treatment with carbendazim 0.05% w/w + soil application with carbofuran @ 0.5 kg a.i/ha was found to be most effective in increasing plant growth parameters of French bean. All the treatments significantly decreased the number of galls, eggmasses and final nematode population in soil except control and the treatment with carbendazim @ 0.3% w/w. However, the treatment with carbofuran @ 1 kg a.i/ha was found to be best in suppressing the number of galls, eggmasses and final nematode population in soil. Maximum reduction in disease incidence was recorded in the seed treatment with T. harzianum @ 5ml/ kg + seed treatment with carbendazim 0.05% w/w + soil application with carbofuran @ 0.5 kg a.i/ha.
Open Access
Morphological and morphometric variations of Hoplolaimus and Helicotylenchus
(AAU, Jorhat, 2020-08) Venkadesh, G; Das, Debanand
Investigations were carried out to study the morphological and morphometric variations of genera Hoplolaimus and Helicotylenchus in relation to host plants and geographical locations of Assam. Total of 163 soil samples were collected from Rice, Maize, Banana, Mango, Jackfruit, Citrus, Pea and Tea, and from different geographical locations viz., Jorhat, Kokrajhar, Sivasagar, Kamrup, Lakhimpur, Dhemaji, Nagaon and KarbiAnglong district of Assam. The populations of both genera under survey were identified as Hoplolaimus columbus, Hoplolaimus indicus, Helicotylenchus crenacauda and Helicotylenchus dihystera. In the study no morphological variations have been observed in genera Hoplolaimus and Helicotylenchus in relation to both host plants and geographical locations. Results of morphometric characters showed that body length, a ratio, oesophagus length, b ratio, oesophageal gland overlapping length, bʹ ratio, ABW, MB, V, Vʹ, stylet length, SE and Pp (only in Hoplolaimus) were regards as least variable characters and considered highly stable in relation to host plants for genera Hoplolaimus and Helicotylenchus. The c ratio, number of tail annules and Pa of females were least variable characters; while, tail length and cʹ ratio were moderately variable characters in Hoplolaimus columbus. The c ratio, cʹ ratio, number of tail annules and Pa of females were regarded as moderately variable characters; while, tail length of females was regarded as highly variable character in Hoplolaimus indicus. In males of H. indicus, tail length, c ratio, cʹ ratio and Pa were regarded as least variable characters; while, bursa of males was regarded as moderately variable character. The tail length, c ratio, cʹ ratio and O of females were regarded as moderately variable characters in relation to host plants of Helicotylenchus dihystera. Influence of geographical locations on morphometric characters revealed that the body length, a ratio, oesophagus length, b ratio, oesophageal gland overlapping length, ABW, MB, V, Vʹ, stylet length and Pp (only in Hoplolaimus) were least variable characters and considered highly stable characters in relation to geographical locations for genera Hoplolaimus and Helicotylenchus. The bʹ ratio, c ratio, cʹ ratio, SE and number of tail annules were least variable characters; while, tail length and Pa of females were moderately variable characters in Hoplolaimus columbus. The bʹ ratio, c ratio, cʹ ratio, SE, number of tail annules and Pa of females were moderately variable characters; while, tail length of was highly variable character in females of Hoplolaimus indicus. In males of H. indicus, bʹ ratio, tail length, SE, Pp, spicule length and gubernaculum length were least variable characters; while, c ratio, cʹ ratio, Pa and bursa of males were moderately variable characters. In case of Helicotylenchus crenacauda the bʹ ratio and SE of females were regarded as least variable characters; while, tail length, c ratio, cʹ ratio and O of females were moderately variable characters. The bʹ ratio, tail length, c ratio and SE of females were regarded as least variable characters; while, cʹ ratio and O of females were regarded as moderately variable characters in relation to geographical locations of Helicotylenchus dihystera.
Open Access
ISOLATION, CHARACTERIZATION AND EVALUATION OF ENDOPHYTIC BACTERIA AGAINST ROOT-KNOT NEMATODES
(AAU, Jorhat, 2020-09) Basumatary, Binita; Das, Debanand
Fifteen endophytic bacteria were isolated from leaves and stems of Solanum lycopersicum and S pimpinellifolium. Morphological characterization of these endophytes revealed that 6 bacteria were gram positive and 9 bacteria were gram negative, 10 bacteria were rod shaped, 3 were coccus shaped and 2 were diplococcus in shape. All 15 bacteria were motile in nature. Biochemical characterization of the isolated endophytes revealed that 9 bacteria showed positive reaction to KOH test while, 6 were negative to KOH test, 11 bacteria showed positive reaction to Citrate and 4 were negative to citrate test. All the 15 bacteria were positive for Gelatine hydrolysis and Catalase test. Six endophytic bacteria showed positive reaction and 9 showed negative reactions for Starch hydrolysis test. Four potential isolates were structurally analysed by using scanning electron microscope and revealed that the length and breadth of BETLI, BETL2, BETL4 and BETS2 were 701.70nm × 348.30nm, 954.l0 nm x 303.10 nm, 984.10nm × 332.90nm and 1422.00nm × 742.00 nm, respectively. Five endophytic bacteria showing potentiality against root-knot nematode were identified by using 16S rRNA, and they were Microbacterium arborescens (BETLI), Bacillus marisflavi (BETL2), Bacillus altitudinis (BETL4), Exigobacterium indicum (BETS2) and Bacillus marisflavi (BETL6). Study on in vitro efficacy of bacterial endophytes against second stage juvenile of root-knot nematode (J2) revealed that all the isolates had the potentiality to significantly increase the mortality of nematodes however, the isolate BETL2 showed the best result on mortality rate (81.47%) of 2 stage juvenile (J2) of Meloidogyne incognita, followed by isolates BETL4 (81.43%) and BETLI (79.07%) Dose-response models were used to determine the concentration of bacterial culture filtrates required to kill 50 per cent juveniles of M. incognita. Four potential bacterial endophytes were tested with different methods of applications (seed treatment, seedling root dip treatment, soil application and their combinations) in pot condition against root-knot nematodes in tomato. All the tested endophytic bacteria significantly increased the plant growth parameters of tomato and reduced the nematode multiplication than untreated control. However, maximum increase in plant growth parameters and decrease in number of galls, egg mass and nematode population in soil was observed in combined application of seed treatment + root dip treatment + soil treatment of Bacillus marisflavi (BETL2) @ 1x 10 cfu/ml of crop.
Open Access
OCCURRENCE AND DISTRIBUTION OF ROOT-KNOT NEMATODE Meloidogyne incognita IN PATCHOULI Pogostemon cablin
(AAU, Jorhat, 2016-07) Buragohain, Pallab; Gogoi, B.B.
Patchouli [Pogostemon cablin (Blanco)] is an important aromatic plant belonging to family Lamiaceae, is a native of Philippines (Arpana et al., 2008). It is grown wild in Malaysia, Indonesia, Singapore and few other countries. Owing to high demand of its essential oil many countries have domesticated this crop. It has multiple uses, it is used in cosmetics, breath fresheners, flavouring baked foods, meat, sausages, etc. Patchouli is very susceptible to root -knot nematode and wilt causing pathogens. In moist and wet weather condition root knot infestation is high in plants which may lead to wilting of plant and kill the plant within 2-3 days due to secondary infection by fungal and bacterial pathogens. The study on “Occurrence and distribution of root-knot nematode Meloidogyne incognita in patchouli Pogostemon cablin” was carried out in the year 2014 -2016, in Golaghat, Nagaon, Jorhat and Sonitpur districts by conducting a survey programme. A total of 123 samples were collected randomly from the four districts. Root-knot infestation was recorded in most of the fields covering the four districts. Root and soil samples were found to be heavily infested by root-knot nematode. The maximum frequency was recorded in Nagaon districts i.e. 38.88 per cent whereas minimum frequency of 21.87 per cent was recorded in Golaghat district. Many fungal pathogens were found to be associated with most of the root-knot infested plants. In the present investigation, three fungal pathogens were found to be associated with root-knot infested plants. They are Fusarium sp., Rhizoctonia solani and Cercospora sp. It has been observed that the patchouli plants are also infested by different insect pests like leaf roller and grass hopper. These insect pests are voracious eater and almost eat up the green foliage leading to defoliation and heavy yield loss.

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