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ThesisItem 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).ThesisItem Open Access Evaluation of Antagonistic Potential of Certain Plants Against Root-knot Nematode, Meloidogyne incognita(AAU, Jorhat, 2019-07) Goswami, Kasturi; Gogoi, Bina B.In the present investigation, an effort was made to evaluate antagonistic potential of some plants against root-knot nematode Meloidogyne incognita. In a screening trial, nine different antagonistic plants viz. Marigold, Garlic, Mustard, Chrysanthemum, Strawberry, Periwinkle, Sesame, Broccoli and Castor were tested against M. incognita. All these antagonistic plants produce very low number of galls, resulting low root-knot index compared to the susceptible control. Among these plants, Marigold, Periwinkle, Garlic were found to be in the resistant category, while Broccoli was found to be moderately resistant. In a root-knot infested field, these four plants were intercropped with root-knot susceptible tomato to see the antagonistic effect of these plants on root-knot nematode. All the treatments with these four intercrops were found to be effective in reducing number of galls, egg masses and final nematode population in soil subsequently increasing plant growth parameters. The treatment with Periwinkle was found to be most effective in increasing the growth parameters viz. shoot length, shoot weight, root length and root weight of Tomato with corresponding decrease in number of galls, egg masses, final nematode population in soil. The increase in yield of Tomato per ha was maximum when tomato was intercropped with periwinkle, followed by Marigold.ThesisItem Open Access MANAGEMENT OF ROOT KNOT NEMATODE (Meloidogyne incognita) IN TOMATO BY BACTERIAL BIOAGENT(AAU, Jorhat, 2019-09) Nyodu, Karter; Das, DebanandInvestigations were carried out to evaluate the efficacy of bacterial bioagents viz., Bacillus subtilis, Bacillus megaterium, Bacillus pumilus and Pseudomonas fluorescens as seed as well as soil treatment against root knot nematode, Meloidogyne incognita on tomato (var. Pusa Ruby). Seed treatment experiment was conducted with thirteen treatments viz., T1: B. subtilis (1×109cfu/gm of talc formulation) @ 10gm/kg of seed, T2: B. subtilis (1×109cfu/gm of talc formulation) @ 20gm/kg of seed; T3: B. subtilis (1×109 cfu/gm of vermi formulation) @ 10 gm/kg of seed; T4: B. subtilis (1×109 cfu/gm of vermi formulation @ 20 gm/kg of seed; T5: B. pumilus (1×109cfu/gm of talc formulation) @ 10gm/kg of seed; T6: B. pumilus (1×109cfu/gm of talc formulation) @ 20gm/kg of seed; T7: B. megaterium (1×109cfu/gm of talc formulation) @ 10gm/kg of seed; T8: B. megaterium (1×109cfu/gm of talc formulation) @ 20gm/kg of seed; T9: B. megaterium (1×109 cfu/gm of vermi formulation) @10gm/kg of seed; T10: B. megaterium (1×109 cfu/gm of vermi formulation) @ 20gm/kg of seed; T11: Pseudomonas fluorescens (1×109cfu/gm of talc formulation) @ 10gm/kg of seed; T12: P. fluorescense (1×109cfu/gm of talc formulation) @20/kg of seed and T13: untreated control. Results revealed that there were a significant increase in plant growth parameters and significant decrease in galls, eggmass and soil nematode population in all treatments over untreated control. However, seed treated with Pseudomonas fluorescens @ 20g/kg seed recorded the best result in increasing the plant growth parameters of tomato and reducing the root knot nematode multiplication followed by Bacillus subtilis (vermi formulation) @ 20g/kg seed. Pot experiment was conducted to evaluate the efficacy of bacterial bioagents as soil application with thirteen treatments viz., T1: Bacillus subtilis (1×109cfu/gm of talc formulation) @ 2%(w/w); T2: B. subtilis (1×109cfu/gm of talc formulation) @ 3%(w/w); T3: B. subtilis (1×109 cfu/gm of vermi formulation) @ 2%(w/w); T4: B. subtilis (1×109 cfu/gm of vermi formulation @ 3% (w/w); T5: B. pumilus (1×109cfu/gm of talc formulation) @ 2%(w/w); T6: B. pumilus (1×109cfu/gm of talc formulation) @ 2% (w/w); T7: B. megaterium (1×109cfu/gm of talc formulation) @ 3% (w/w); T8: B. megaterium (1×109cfu/gm of talc formulation) @ 2% (w/w); T9: B. megaterium (1×109 cfu/gm of vermi formulation) @ 3% (w/w); T10: B. megaterium (1×109 cfu/gm of vermin formulation) @ 3% (w/w); T11: Pseudomonas fluorescens (1×109cfu/gm of talc formulation) @ 2% (w/w); T12: Pseudomonas fluorescens (1×109cfu/gm of talc formulation) @3% (w/w) and T13: Untreated control; The result revealed that all the treatments significantly increased plant growth parameters and significantly decreased gall per root system, eggmass per root system and final root knot nematode population in soil over untreated control. However, maximum plant growth parameters and reduction in root knot nematode multiplication were recorded in soil treated with Pseudomonas fluorescens @ 3% (w/w) followed by Bacillus subtilis (vermi formulation) @ 3% (w/w) whereas minimum was recorded in untreated controlThesisItem Open Access EFFICACY OF ENTOMOPATHOGENIC NEMATODES (EPNs) AGAINST MAJOR INSECT PESTS OF TEA(AAU, Jorhat, 2019-07) BHARATH, AMURI; Devi, GitanjaliA total 200 soil samples were collected from tea plantation areas of district, Jorhat, Assam and were assessed for entomopathogenic nematodes using the Galleria baiting technique. Out of 200 soil samples, EPNs were found in 2 soil samples with 1% frequency of occurrence. One isolate of Oscheius sp. (0.5%), was isolated from Experimental farm for plantation crops, Section-4, 10, 19 AAU, Jorhat and another Heterorhabditis sp. (0.5%) was isolated from Chetiagoan, Jorhat. Morphological and morphometrical characters were used in the identification of nematode isolates. The identified species were Heterorhabditis bacteriophora, and Oscheius chongmingensis. In infectivity study, indigenous isolates of EPNs, Heterorhabditis bacteriophora and Oscheius chongmingensis tested in the laboratory bioassay, caused mortality of tea mosquito bug, Helopeltis theivora and bunch caterpillar,Andraca bipunctata. Fifty, 60 and 70 per cent mortality of Helopeltis theivora by H. bacteriophora at 150 IJs/insect was observed at 48 h, 72 h and 96h respectively. With the increase in the exposure period to 96 h, H. bacteriophora could induce up to 90% mortality of the tested insect at the dose of 250 IJs. Similarly, mortality of Helopeltis theivora increased with increase in the dosage of O. chongmingensis and recorded 50, 60 and 70 per cent mortality at 200 IJs/insect at 48 h, 72 h and 96h. Bioassay of H. bacteriophora and O. chongmingensis against the 3rd instar larvae of Andraca bipunctata indicated that at 250 IJs/larva recorded 70 and 60% mortality in 48 hours of exposure, while 100 and 90% mortality of Andraca bipunctata was recorded at 96h. H. bacteriophora was more pathogenic than Oscheius chongmingensis against Helopeltis theivora and Andraca bipunctata based on LD50 values at 48 h, 72 h and 96 h.ThesisItem Open Access MECHANISM OF LANTANA CAMARA LEAF EXTRACTS IN THE MANAGEMENT OF MELOIDOGYNE INCOGNITA ON TOMATO(AAU, Jorhat, 2019-07) Bordoloi, Kankana; Bhagawati, B.An experiment was carried out on the mechanism of Lantana camara leaf extract in the management of Meloidogyne incognita on tomato. For this, leaf extract of L. camara (25gm/75ml w/v) were evaluated at 25, 50, 75 and 100 percent concentration through egg hatch inhibition and larval mortality test. The result of the in-vitro efficacy test showed that maximum egg hatch inhibition of M.incognita was recorded in the 100 percent concentration of L. camara leaf extract where as minimum was recorded in the 25percnet concentration after 7 days of exposure time. The maximum mortality of M. incognita J2was recorded in the 100 per cent concentration of L. camara leaf extract where as minimum was recorded in the 25 per cent concentration after 24, 48, 72 and 96 hours of exposure time. No mortality was recorded in the control treatment i.e. sterile distilled water. It was observed that there was an increasing trend in the mortality of J2 with increase in the concentration and time of exposure. Similarly, egg hatch inhibition was also found to be more with increase in the concentration. A pot experiment was conducted to explore the biochemical mechanism of leaf extracts of L. camara in the management of M. incognita on tomato. For this the activity of defence related enzymes viz., peroxidase (PO), polyphenoloxidase (PPO) and total phenol content were observed at 25,50,75 and 100 percent concentration of L. camara leaf extract after 35and 45 DAI of M .incognita in tomato. Among the different concentrations, highest activity of peroxidase (PO), polyphenoloxidase (PPO) and total phenol content was observed at 100 percent concentration while the minimum activity was recorded in the 25 percent concentration both after 35and 45 DAI. However, maximum activity of the biochemical compounds was recorded at 35 DAI while the same declined at45 DAI. The lower concentration of L. camara leaf extract viz., 25 and 50 percent showed stimulatory effect on plant growth parameter whereas higher concentrations viz., 75 and 100 percent concentration of L. camara leaf extract showed inhibitory effect on plant growth. The maximum plant growth parameter like shoot height, shoot weight (fresh) and root length and root weight (fresh), dry shoot weight were recorded in the 50 percent concentration of L. camara leaf extract where as the minimum was recorded in the nematode alone treatment. The minimum nematode multiplication like number of galls, number of eggmasses and final nematode population in soil were recorded in the 100 percent concentration of L. camara leaf extract followed by 75, 50 and 25 percent concentration.