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Assam Agricultural University, Jorhat
Assam Agricultural University is the first institution of its kind in the whole of North-Eastern Region of India. The main goal of this institution is to produce globally competitive human resources in farm sectorand to carry out research in both conventional and frontier areas for production optimization as well as to disseminate the generated technologies as public good for benefitting the food growers/produces and traders involved in the sector while emphasizing on sustainability, equity and overall food security at household level.
Genesis of AAU -
The embryo of the agricultural research in the state of Assam was formed as early as 1897 with the establishment of the Upper Shillong Experimental Farm (now in Meghalaya) just after about a decade of creation of the agricultural department in 1882. However, the seeds of agricultural research in today’s Assam were sown in the dawn of the twentieth century with the establishment of two Rice Experimental Stations, one at Karimganj in Barak valley in 1913 and the other at Titabor in Brahmaputra valley in 1923. Subsequent to these research stations, a number of research stations were established to conduct research on important crops, more specifically, jute, pulses, oilseeds etc. The Assam Agricultural University was established on April 1, 1969 under The Assam Agricultural University Act, 1968’ with the mandate of imparting farm education, conduct research in agriculture and allied sciences and to effectively disseminate technologies so generated. Before establishment of the University, there were altogether 17 research schemes/projects in the state under the Department of Agriculture. By July 1973, all the research projects and 10 experimental farms were transferred by the Government of Assam to the AAU which already inherited the College of Agriculture and its farm at Barbheta, Jorhat and College of Veterinary Sciences at Khanapara, Guwahati.
Subsequently, College of Community Science at Jorhat (1969), College of Fisheries at Raha (1988), Biswanath College of Agriculture at Biswanath Chariali (1988) and Lakhimpur College of Veterinary Science at Joyhing, North Lakhimpur (1988) were established. Presently, the University has three more colleges under its jurisdiction, viz., Sarat Chandra Singha College of Agriculture, Chapar, College of Horticulture, Nalbari & College of Sericulture, Titabar. Similarly, few more regional research stations at Shillongani, Diphu, Gossaigaon, Lakhimpur; and commodity research stations at Kahikuchi, Buralikson, Tinsukia, Kharua, Burnihat and Mandira were added to generate location and crop specific agricultural production packages.
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ThesisItem Open Access PEST COMPLEX OF BHUT JOLOKIA AND THEIR MANAGEMENT(AAU, Jorhat, 2017-07) Thangjam, Rojeet; Borah, R.K.Field and laboratory experiment on pest complex and their natural enemies, identification and detection of insect vectors, integrated management of important pest of Bhut Jolokia and cost benefit ratio of different treatment modules were carried out during rabi (2014-15 and 2015-16) at Horticultural Orchard, Department of Entomology and Department of Plant Pathology, Assam Agricultural University, Jorhat (Assam). Altogether 110 species of arthropods were found to be associated with Bhut Jolokia at Jorhat, out of which 19 species were identified as pest, 64 as natural enemies and 27 species as casual visitors. Among the different insect pests recorded, 6 species were identified as “major” and they were Aphis gossypii (Glover), Myzus persicae (Sulzer), Bemisia tabaci (Gennadius), Bactrocera latifrons (Hendel), Scirtothrips dorsalis (Hood) and Polyphagotarsonemus latus (Banks). Among the natural enemies recorded, 44 species of predators, 13 species of parasitoids and one species of entomopathogenic fungus belongings to different orders have been reporting for the first time adding the number of natural enemies in Bhut Jolokia ecosystem. Moreover, among the dipteran predators, Syrphid fly (Lathyrophthalmus arvorum) has been reporting for the first time from Assam. All the genotypes of Bhut Jolokia collected from Assam, Manipur and Nagaland showed susceptible to viral diseases. However, the lowest incidence was observed in KCM2 (33.33%) and KCN1 (33.33%). Among the insect pests, 3 species viz., B. tabaci, A. gossypii and M. persicae have also been identified as a vector of Chilli Leaf Curl Virus (ChLCV), Cucumber Mosaic Virus (CMV) and Potato Virus Y (PVY), respectively during the investigation and they were confirmed through DAS-ELISA and PCR technique. Among the different treatment modules, module M2 that includes seedling root dip treatment with imidacloprid 17.8 SL @ 40g a.i./ha for 30 minute just before transplanting + growing of border crop (okra) + spraying of imidacloprid 17.8 SL @ 40g a.i./ha at 20 days after transplanting at 15 days interval (4 sprays) was found to the best performer in suppressing the population of aphid and whitefly followed by module M4 that includes seedling root dip treatment with imidacloprid 17.8 SL @ 40g a.i./ha for 30 minute just before transplanting + growing of border crop (maize) + spraying of lambda cyhalothrin 5 EC @ 25g a.i./ha starting from 20 days after transplanting (4 sprays) which were significantly superior over untreated control module M6. All the treatment modules had also significantly reduced the viral disease incidence as compared to untreated control. But the module M2 was the most effective in reducing the viral disease incidence followed by module M4 in both the seasons. However, these two modules greatly affect the population of coccinellids and spiders. The insecticidal treatment modules had significant effect in reducing the insect pest population and also the incidence of viral diseases thereby increasing the yield of Bhut Jolokia during the investigation. The highest yield was obtained in module M2 (3564.44kg/ha) followed by M4, M1, M3 and M5 (2687.94, 2303.98, 2100.15 and 1511.41kg/ha, respectively). The results on cost benefit ratio revealed that the highest was recorded in module M2 (1: 4.85) followed by M4 (1: 3.37) and M1 (1: 2.13).ThesisItem Open Access BIOECOLOGY ON Lepidiota sp. Indet. (COLEOPTERA: SCARABAEIDAE)(AAU, Jorhat, 2017-07) Gogoi, Dhanalakhi; Baruah, A.A.L.H.Field and laboratory experiments were carried out at Ramie Research Station, Sorbhog and nearby areas and at Soil Arthropod Laboratory of the Department of Entomology, Assam Agricultural University, Jorhat during 2013 - 2017 to engender comprehensive information on the bioecology of Lepidiota albistigma Burmeister, (Coleoptera: Scarabaeidae), a major white grub species endemic to Lower Brahmaputra Valley of Assam. Experimental results confirmed the annual life cycle of L. albistigma with a mean duration of 336.30 ± 14.25 days. The pre-ovippositional, ovipositional and post-ovipositional period were 8.83 ± 0.75, 3.03 ± 0.76 and 9.13 ± 0.73 days, respectively. The mean fecundity was 22.20 ± 1.1 numbers. Eggs were creamywhite, opaque and elongated in shape with mean length and breadth of 5.61 ± 0.40 mm and 4.32 ± 0.36 mm, respectively. Mean incubation period was found to be10.73 ± 2.02 days. There were three larval instars with the duration of third instar (237.11 ±4.86 days) being significantly longer than the first (22.29 ± 1.10 days) and second (39.65 ± 2.90 days) instar. Mean pupal duration was recorded to be 23.36 ± 1.18 days. The mean length and width of first (16.12 ± 0.77 and 4.37 ± 0.54 mm), second (37.60 ± 1.30 and 9.16 ± 0.46) and third (80.28 ± 2.61 and 13.68 ± 0.63 mm) instar grubs were significantly different from each other.The mean length and width of pupae were recorded to be 43.76 ± 1.32 and 16.53 ± 0.60 mm, respectively. Sexual dimorphism based on adult morphometrics revealed that females (61.58 ± 1.64 mm) were significantly longer than males (57.34 ± 0.85 mm). The length of head plus thorax and abdomen were significantly longer in females (27.23 ± 0.55 mm and 24.36 ± 1.30 mm) than in males (23.88 ± 0.41 mm and 23.80 ± 1.30 mm). The mean length of forelegs (31.20 ± 0.79 mm), mid legs (32.77 ± 0.30 mm) and hind legs (42.42 ± 0.97 mm) were significantly longer in females than the males (Foreleg: 28.244 ± 0.61, Mid legs: 30.42 ± 0.18 mm; Hind leg: 41.32 ± 1.41 mm) but the claws in males were strongly bifid. The female alimentary canal (324.94 ± 7.05 mm) was significantly longer than males (315.80 ± 8.74 mm). Both male and female reproductive system exhibited synchronous attainment of sexual maturity. Distinct sexual dimorphism was also observed in the antennal segments and in antenna sensilla types. Scanning electron microscopic studies revealed 14 different types of sensilla in male and 9 types in female. Lamellae were significantly longer in males. Field surveys revealed that mango, guava, mussaenda, ixora, Assam lemon, arecanut, periwinkle, pomelo, betelvine, thuja, croton and black pepper were the primary hosts for adults. Feeding status of adults was further confirmed by presence of food materials in their dissected alimentary canals. Further, sterozoom microscopic images of mandibles and maxillae of both sexes exhibit dentations which indicated that mandibles and maxillae were fitted for phytophagy with probable application in digging of soil for burrowing. Host specificity test revealed that potato, colocassia, green gram and sugarcane to be the most preferred hosts of grubs. Studies on habitat selection by grubs of L. albistigma at five different ecosystems revealed thatgrubs were significantly more abundantat grasslands which were located near water sources. Grubs of L. albistigma were more abundant at soil depths of 0 - 10 cm and 11 - 20 cm in grassland and cultivated lands. In grasslands, grubs showed significant preference for soil depths of 0 - 10 cm (3.79 ± 3.34) and 11 -20 cm (2.31 ± 2.09). In cultivated fields, the highest population was recorded at the depth of 11 - 20 cm (2.78 ± 1.54) which significantly differed with other depths. There is no significant difference in abundance of grubs at 0 - 10 cm (1.40 ± 1.22), 21- 30 cm (1.40 ± 1.22) and 31- 40 cm (0.57 ± 1.22). The mechanism of survival of grubs were examined by means of a simulation model which displayed that the grubs were atleast able to survive upto 3 days under water whereas, under simulated conditions they survived upto 15 days. SEM results indicated presence of one pair of thoracic and eight pair of abdominal fictional spiracles which denoted that the respiratory system of the grub is peripneustic. The spiracles are characterized by external structures consisting of a central bulla which is surrounded by a smooth cresent shaped sieve/spiracular plate with numerous aeropyles. Absence of a conventional spiraclular opening, presence of a convex projecting central bulla in place of the opening, sclerotized and smooth sieve plate with ultramicroscopic (< 3 micron wide) aeropyles might have provided protection against entry of water into the tracheoles, allowing only gaseous exchange Observations on relative abundance of L. albistigma indicated that the highest population of grubs were recorded during the month of August whereas lowest was recorded during December, 2014 - 15. Correlation studies between L. albistigma grubs and soil physico-chemical parameters revealed that among all physical parameters, sand (r = -0.693) and silt content (r = -0.845) had significant negative correlations whereas, clay (r = 0.839) recorded a significant positive correlation. Among the chemical parameters, soil organic matter content (r = 0.901) and available nitrogen (r = 0.963) had significant positive correlation with grub population. Microbial investigation on the gut content of third instar grubs of L. albistigma revealed 20 different bacterial cultures of which 5 bacterial cultures designated as B2, B5, B11, B14 and B17 had the highest colony forming unit/ml. Bacterial flora considerably varied in size, colour, pigmentation, margins and elevation and as well as in utilization of carbohydrates and their response to various enzymes.ThesisItem Open Access ECOLOGY AND MANAGEMENT OF MOUND BUILDING TERMITES(AAU, Jorhat, 2017-07) Himangshu Mishra; Bhattacharyya, BadalStudy on ecology and management of mound building termites were carried out in Jorhat and Golaghat district of Assam. Ecological studies were conducted at four different habitats viz., forest, agriculture, rural and urban habitat of both the districts during 2015 and 2016 while management of termites in tea ecosystem was conducted in experimental plot under department of tea husbandry and technology, AAU. Sampling in different habitats revealed 8 species of termites from both the districts. Among the 8 different species, 5 species were belonged to Macrotermitinae subfamily, whereas other 3 species belonged to Nasutitermitinae, Kalotermitinae and Amitermitinae subfamily. The genus Odontotermes were found dominant and consisted of four species viz., Odontotermes obesus (Rambur), O. feae (Wasmann), O. parvidens (Holmg. and Holmg.) and O. kapuri (Roonwal and Chhotani) while the remaining 4 species were belonged to different genera and these were Microtermes mycophagous (Desneux), Trinervitermes biformis (Wasmann), Neotermes buxensis (Roonwal and Sen-sarma) and Speculitermes chadaensis (Chatterjee and Thapa). Four different feeding groups of termites were recorded among which soil, litter and fungus feeder were dominantly found. Moreover, out all eight species two termites (O. obesus and O. feae) were dominantly distributed in different habitats of both the district. Morphometric studies of some termite species under Macrotermitinae subfamily revealed that O. feae were comparatively bigger than O. parvidens, M. mycophagous, O. obesus and O. kapuri. Collection of termites from different habitats revealed that higher population of the termite species were recorded from forest habitats than rural, agriculture and urban habitats of both the district. In addition it was also observed that forest habitats had highest mound density per ha (4.42 & 4.35 and 4.50 & 4.40) than rural (3.85 & 3.55 and 3.40 & 3.20), agricultural (3.25 & 3.05 and 3.30 & 3.15) and urban (3.15 & 3.00 and 3.25 & 3.10) sites of Jorhat and Golaghat district respectively. Ecology of mounds were studied through proper observation on nesting patterns of O. obesus and O. feae mounds in different habitats of both the district. Nesting pattern observed in mounds of forest habitats recorded comparatively higher sizes of basal diameter, height, incubation cavities, nursey cell, diameter and depth of the royal chamber from the ground level, moreover the mounds noticed in forest habitats also had higher sizes of length and width of the fungal comb than rural, agriculture and urban habitat of Jorhat and Golaghat. Caste composition recorded in the mounds of different habitats confirmed that higher numbers of worker, soldiers were collected from the mounds of forest habitats. Termite population of O. obesus and O. feae also recorded in the Assam Agricultural University, Campus and the study found fluctuating trend of termite castes in different months during March, 2015 to February, 2016. Correlation of population with mound dimension and weight of the fungal comb revealed that both O. obesus and O. feae showed positively significant correlation with basal diameter [0.982*(0.001) & 0.956*(0.001)], height [0.975*(0.001) & 0.925*(0.001)] and weight of the fungal comb [0.921*(0.002) & 0.925*(0.001)] respectively. Observation on termitophiles and inquilines associated with the mounds of O. obesus and O. feae, stated that scarabaeids and carabids were highly dominant where as staphylids, elaterids, formicids, arachnids and diplopods were moderately dominant termitophiles. Out of different types of inquilines recorded, annelids were highly dominant whereas molluscs and squamets were found moderately and less dominant inquilines. Study on fungal and bacterial colony in the mounds soils of different habitats revealed that, mound soils of forest habitat exhibited higher numbers of bacterial and fungal population than rural, agricultural and urban habitats of both the district. Physicochemical properties of mound soils of different habitat exhibited higher amount of silt (%), clay (%), soil moisture (%), organic carbon (%), available nitrogen (g/kg) and soil microbial biomass (g/kg) than the surrounding mound soil collected from different habitats of both the district. Management of the termites in tea ecosystem revealed that Metarhizium anisopliae registered least number and portion of infestation (13.86 & 12.04% and 14.11 & 12.04%) and showed statistical parity with Heterorhabditis indica treated plant (14.49 & 13.73 and 15.60 & 14.26%) after 30 and 60 days of treatment. The tea plants treated with Jatropha oil 50 EC and Neem oil 30 EC exhibited number of infestation (15.52 & 16.56%) and portion of infestation of (14.60 and 15.36%) while the untreated control plants recorded 38.44 & 37.35 and 40.32 & 39.48 per cent of infestation after 30 and 60 days of treatment respectively.ThesisItem Open Access NEUROENDOCRINE REGULATION OF LIPID METABOLISM IN Periplaneta americana(AAU, Jorhat, 2017-07) Borah, Nirmali; Hazarika, L. K.The present investigation on Neuroendocrine regulation of lipid metabolism in Periplaneta americana was conducted during 2013-2017 in the Physiology laboratory of Department of Entomology, Assam Agricultural University, Jorhat. A total of six instars were recorded during the biology study of P. americana. The pre oviposition period, incubation period, nymphal period, adult longevity and total life cycle period of P. americana during the present investigation were 8.4±1.40, 40.66±4.43, 326.83±76.30, 272.76±57.40 and 367.50±74.95 days, respectively. The duration of each nymphal instar from first to last were 40.70±4.41, 44.96±2.66, 56.20±1.16, 58.60±1.28, 61.11±3.44 and 65.26±1.47 days, respectively. The mean ootheca length, width and weight recorded were 10.53±1.48 mm, 5.23±0.45 mm and 125.73±16.35 mg, respectively. The mean number of oothecae produced by a female were 13.86±1.56 with 14.93±1.89 eggs per ootheca. The number of eggs hatched per ootheca was 12.76±2.20 with a hatching percentage of 90.63±5.57 per cent. The body length of each instar increased significantly from the first (3.26±0.60 mm) to the sixth (39.33±2.04) and attained its peak in adult stage, exhibiting sexual dimorphism, the male was comparatively longer (43.30±6.38 mm) than the female (39.43±2.03 mm). The antennae length recorded from first instar to sixth instar were 5.01±0.13, 14.41±0.61, 15.17±0.30, 23.62±0.98, 25.01±0.13 and 45.02±0.25 mm, respectively. The adult male and female antennae length recorded were 50.08±1.61 and 43.03±3.85 mm. The head width from first instar to sixth instar were 1.04±0.04, 1.51±0.08, 2.59±0.32, 3.00±0.28, 4.00±0.09 and 4.02±0.08 mm, respectively. The head width of adult male and female were 5.00±0.10 and 4.11±0.18 mm. The pronotum size (length width) recorded from first instar to sixth instar were (1.06±0.06) (1.07±0.70) mm, (1.15±0.08) (1.17±0.09) mm, (3.05±0.22) (3.71±0.37) mm, (4.86±0.16) (6.94±0.19) mm, (6.92±0.11) (8.87±0.15) mm, (7.96±0.06) (9.03±0.10) mm respectively. The pronotum size (length width) of adult male and female were (9.45±0.57) (10.96±0.71) and (9.14±0.46) (10.80±0.71) mm, respectively. A positive and significant correlation was observed between female weight and ootheca number (r = 0.743) and weight (r = 0.747). The weight of males increased after adult ecdysis till first mating on day 5 (1.11±0.03 g), and then decreased to day 30 (0.87±0.03 g) after emergence, then again increased from day 40 onwards, however, subsequently it maintained fairly a constant weight (1.22±0.11 g). The weight of females began to increase steadily during its adulthood (1.27±0.04 g) and peaked (1.40±0.08 g) on day 30. The highest weight was recorded on day 75 (1.43±0.07 g). A decrease in body weight was observed on day 80 (1.32±0.15 g) and day 85 (1.31±0.06 g), which were coincide with ootheca deposition. The lipid content of the adult male P. americana increased from day 1 (103.70±0.67 mg) to day 50 (281.93±1.94 mg) and reached its peak on day 65 (283.40±2.72 mg) after which it starts declining. The lipid content of the older males stayed fairly constant. The lipid content of adult female increased significantly in a similar trend with that of male and reached peak from day 60 (326.66±1.25 mg) to day 70 (326.23±1.11 mg) after that it remained fairly constant. A significant drop in the lipid content was observed on day 80 (217.16±2.98 mg). The correlation study revealed that the body weight was positively correlated with lipid content (mg) of both male and female P. americana. The exposure of adults to growth hormones suppressed adult emergence and caused morphological abnormalities producing either nymphoids or giant nymphs and adultoids. Among the different concentration of growth hormones tested 5 ppm methoprene and 5 ppm JH III were found to be effective in lowering the body weight and lipid content of P. americana when applied either topically or by injection. An adult male and female P. americana imbibed 62.66±7.18 ml and 66.33±8.32 ml of water per day when they were deprived of water for 24 hours, but after 48 hours of starvation water consumption was 70.63±9.44 and 80.07±9.51 ml per day for adult male and female, the latter were significantly higher than the former. Very low impact was observed at short deprivation periods and it was observed that all the females died before the longest deprivation period ended. The hatching percentage was found to be less in case of the ootheca produced by the deprived female than that produced by a normal female P. americana.ThesisItem Open Access MOLECULAR BASIS OF VARIETAL RESISTANCE OF BRINJAL AGAINST Leucinodes orbonalis Gunee (Lepidoptera: Pyralidae) AND ITS ECOFRIENDLY MANAGEMENT(AAU, Jorhat, 2017-07) Choudhury, Kasturi; Borah, R. K.The investigations on “Molecular basis of varietal resistance of brinjal against Leucinodes orbonalis Guenee (Lepidoptera: Pyralidae) and its eco-friendly management” were carried out at College of Agriculture, Assam Agricultural University, Jorhat during 2013-14 and 2014-15. Studies on the varietal screening of brinjal varieties revealed that the minimum shoot as well as fruit infestation on number basis recorded on variety Khorua-1 with 2.96 and 9.31 per cent, respectively. The minimum fruit infestation on weight basis was recorded on variety Brinjal long green (5.54 %). The highest infestation of shoot (17.85 %) and fruit infestation on number basis (36.52 %) and weight basis (36.08 %) noted on variety JC- 1. The remaining varieties viz., Brinjal long green , Khorua-2, White brinjal, Borbengena, Sagalihingia, Tita bengena, Pusa purple cluster and Pusa purple long registered shoot infestation ranged from 3.05 to 13.69 per cent, 9.70 to 21.81 per cent fruit infestation on number basis and 5.54 to 21.84 per cent on weight basis. The highest brinjal fruit yield was recorded on JC-1 (238.69 q/ha) followed by Pusa purple long (177.83 q/ha). The minimum fruit yield was recorded on Khorua-2 (30.69 q/ha). Varieties Brinjal long green, Khorua-1, White brinjal and Khorua-2 were designated as resistant to L. orbonalis as fruit damage recorded between 1.0 to 10.00 per cent. The fairly resistant varieties to L. orbonalis comprised of Pusa purple cluster, Borbengena and Sagalihingia which registered fruit infestation ranged from 11.0 to 20.0 per cent. Two varieties viz., Khorua-3 and Pusa purple long were categorized as tolerant (21.0 to 30.0%) fruit infestation. The varieties viz., Tita bengena and JC-1 were found susceptible to shoot and fruit borer with fruit infestation between 31.0 to 40.0 per cent. The influence of morphological and biochemical factors on the infestation by L. orbonalis revealed that the correlations of shoot diameter (r= 0.646), plant height (r=0.291), leaf thickness (r=0.314), and leaf area (r=0.137) with shoot infestation by L. orbonalis were positive but did not show any significant correlation , however the effect of trichome density (r = -0.140) exhibited negative association with shoot infestation , while length of pedicel (r=0.388), length of calyx (r =0.473) and fruit length (r =0.234) were statistically significant but did not show any significant correlation with fruit infestation. Among biochemical contents in shoots, the total phenol (r= -0.584), peroxidase (r= - 0.796) and polyphenol oxidase (r = -0.734) showed significantly negative correlation with per cent shoot infestation caused by L. orbonalis. In regards to the studies of defense response gene, the relative expression level of Ascorbate Peroxidase1 (AP1) and PR3 gene were significantly higher in resistant Khorua variety than in the susceptible JC-1 variety in response to L. orbonalis regurgitant. The relative expression of AP1 and PR-3 gene in Khorua brinjal were greater than 45 and 40 fold higher than untreated control, respectively. However, the expression of this gene was significantly lower in susceptible brinjal, JC1. Six different modules were tested against L.orbonalis in order to develop an ecofriendly management tactics against this pest. Among the different treatment modules, Module III that includes seedling root dip treatment by Imidacloprid 17.8 SL @ 0.5 ml/lit for 3 hrs + Clean cultivation at 15 days interval +Clipping of infested shoots and destruction of infested fruits +Intercrop with Coriander +Spraying with Spinosad 45 SC @ 0.1ml/lit were found to the best performer in suppressing of shoot infestation (6.04% and 6.95%) in 2013- 14 and 2014-15, respectively as well as fruit infestation on number basis (15.71%) and weight basis (17.16%) by L. orbonalis. All the treatment modules had also significantly reduced the shoot and fruit infestation as compared to untreated control. The maximum total increased in yield over untreated control was recorded in Module III (162.17 q/ha) followed by Module IV (133.91 q/ha), and Module V (95.47 q/ ha) while, minimum total increase in yield (88.18 q/ ha) over untreated control was recorded in ModuleI followed by Module II (92.92 q/ ha). The maximum net profit of Rs. 322790.00/ ha was obtained in Module III followed by Module IV (Rs. 279910.00/ ha), Module II (Rs. 218065.00/ ha) and Module I ( Rs. 205465.00 /ha) and Module V (Rs. 195125.00/ha) while, the minimum net profit of Rs. 97920.00 was obtained in control plot (Module VI). The maximum B:C ratio of 4.06 was obtained in Module III followed by Module IV (3.50), Module II (2.72) and Module I (2.40), Module V (1.82) and Module VI (1.60).ThesisItem Open Access REACTION OF SOME AROMATIC RICE VARIETIES AGAINST MAJOR INSECT PESTS AND THEIR MANAGEMENT(AAU, Jorhat, 2017-07) Singh, Hemam Ramananda; Borah, D.K.Investigation on reaction of some aromatic rice varieties against major insect pests and relationship between morphological and biochemical properties of the rice varieties with insect pest incidence and evaluation of some promising insecticides and neem based insecticides to major insect pests and their natural enemies were carried out at the Assam Agricultural University, Jorhat, during Kharif, 2013 and 2014. From the present investigation, it was found that among the 13 aromatic rice varieties screened during Kharif 2013 and 2014, none of the varieties showed resistance to stemborer. However three varieties viz. Boga Maniki Joha, Koli Joha and Ronga Joha showed Moderately Resistance during vegetative stage and Moderately Susceptible during reproductive stage. In case of case worm and leaf folder, none of the varieties were found to be resistant during the investigation. The morphological characters of the aromatic rice varieties showed non-significant correlation with the incidence of insect pests studied. In case of biochemical properties, carbohydrate showed significant positive correlation with case worm and leaf folder infestation, while non-significant positive correlation with stem borer. Nitrogen showed significant positive correlation with stem borer infestation but non-significant positive correlation to case worm and leaf folder infestation. Chlorophyll, fat and protein showed non-significant positive correlation with the entire insect pest studied. However, phenol showed significant negative correlation with stem borer and leaf folder and non-significant negative correlation with case worm. Investigation on efficacy of some insecticides revealed that Fipronil 80 WG @ 40 g a.i./ha was superior in reducing the infestation by stemborer in terms of both DH and WEH followed by Flubendiamide @ 24g a.i./ha, Lambda-Cyhalothrin @ 25g a.i./ha and Thiamethoxam @ 25g a.i./ha. In case of case worm, the percent reduction over control was highest in Flubendiamide @ 24g a.i./ha (78.31) followed by Fipronil 80WG @40g a.i./ha (75.00), Thiamethoxam @ 25g a.i./ha (69.01) and Lambda-Cyhalothrin @ 25g a.i./ha (66.12) respectively. Similarly in case of leaf folder, the present finding showed that Flubendiamide @ 24g a.i./ha was most effective and it was equally effective statistically with Thiamethoxam @ 25g a.i./ha and Fipronil 80WG @ 40g a.i./ha followed by Lamda-Cyhalothrin @ 25g a.i./ha. The highest yield was recorded in Fipronil 80WG @ 40g a.i./ha followed by Flubendiamide 39.35 SC @ 24g a.i./ha and Thiamethoxam @ 25g a.i./ha however the highest benefit-cost ratio was observed in Thiamethoxam @ 25g a.i./ha. Data on the effect of treatments on natural enemies revealed that Chlorpyriphos @ 500g a.i./ha recorded the least population of odonates and coccinellids followed by Lambda-Cyhalothrin @ 25g a.i./ha and Thiamethoxam @ 25 g a.i./ha respectively while Lambda-Cyhalothrin @ 25g a.i./ha recorded the least population in case of spider followed by Chlorpyriphos @ 500g a.i./ha and Thiamethoxam @ 25g a.i./ha respectively. Neem insecticide @ 3ml/L showed least effect on spider and coccinellids followed by Flubendiamide @ 24g a.i./ha and Spinosad @ 50g a.i./ha respectively. However Flubendiamide 24g a.i./ha showed the least effect on odonates followed by neem insecticide @ 3ml/L and Spinosad @ 50g a.i./ha respectively.