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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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  • ThesisItemOpen Access
    NUTRITIONAL PROFILING OF SOME EDIBLE SERICIGENOUS INSECTS OF MANIPUR
    (2023) Singha, Th. Aruna; Bhattacharyya, Badal
    Laboratory experiments were carried out to assess the nutritive value of four edible sericigenous insect species viz., Bombyx mori L., Anthrerea proylei J., Antherea frithi M. and Cricula trifenestrata H. based on their proximate & elemental content, amino & fatty acid profiles, antioxidant & anti-nutritional properties as well as their microbial aspects in the Soil Arthropod Pests Laboratory, Department of Entomology, Post Graduate Laboratory, Department of Biochemistry and Agricultural Chemistry, Department of Plant Pathology, Assam Agricultural University, Jorhat during 2019-2022. Edible sericigenous insect species cocoons were collected from various locations covering five districts of Manipur. The powdered samples of the pupae were considered for biochemical and microbial analysis. The proximate analysis of four edible sericigenous insect species had significant variation. The moisture content ranged from 2.038-6.075 per cent and the highest moisture content was observed in A. proylei (6.075%) and A. frithi registered the least moisture content (2.038%) indicating that suitability of sericigenous pupal powder for preservation for a reasonable period of time without any probable risk of any microbial deterioration. The carbohydrate content of the studied species was found maximum (12.130%) in C. trifenestrata and the lowest (2.250%) was recorded in A. proylei. Appreciable amounts of crude protein content were estimated in all the studied species which ranged from 59.315- 69.418 per cent. The highest (69.418%) crude protein was registered in A. frithi and it was found to be significantly superior over the rest of the species. The estimated crude protein content of A. proylei, C. trifenestrata and B. mori were 65.383, 61.463 and 59.315 per cent, respectively. Crude fat content registered in the studied species varied significantly and ranged from 19.213-30.725 per cent. The highest (30.725%) crude fat content was recorded in B. mori followed by A. proylei (29.750%) and C. trifenestrata (28.738%), whereas A. frithi recorded the lowest (19.213%) amount of crude fat content. The crude fibre content varied from 2.213-8.450 per cent and C. trifenestrata registered a significantly high amount of crude fibre (8.450%), whereas the lowest was found in B. mori (2.213%). The highest (5.275%) ash content was observed in A. proylei, whereas the lowest (4.175%) was registered in C. trifenestrata. The ash content of mulberry silkworm B. mori (5.150%) was statistically at par with the A. frithi (5.150%). While analyzing the energy content (kcal/100 g) of all the four species, the maximum energy content (560.205) was estimated in A. proylei followed by C. trifenestrata (556.035) and B. mori (534.885), whereas A. frithi detected the lowest energy content of 465.453 kcal/100 g. Altogether 9 minerals as elemental composition were estimated in all the studied species. The mineral analysis indicated that the concentration of macro elements viz., potassium, calcium and magnesium were significantly higher in A. frithi (70.295, 13.993 & 25.889 mg/100 g), whereas the lowest amount (65.663, 8.790 & 23.526 mg/100 g) potassium, calcium and magnesium were observed in C. trifenestrata. However, the highest sodium and phosphorus content (36.026 & 22.429 mg/100 g) were recorded in B. mori and the least amount of sodium (26.489 mg/100 g) and phosphorus (16.062 mg/100 g) were found in C. trifenestrata. Considerable amounts of micro elements like iron was recorded the highest (26.639 mg/100 g) in B. mori. The lowest iron content was observed in A. proylei (8.315 mg/100 g). Zinc, manganese and copper content (mg/100 g) was estimated to be the highest (21.709, 5.445 and 3.123) in A. frithi which showed statistical superiority over other species whereas C. trifenestrata registered with the lowest zinc (15.381 mg/100 g), manganese (1.209 mg/100 g) and copper (0.997 mg/100 g) content. Among all the amino acids 19 common amino acids, 8 were found essential. Glutamic acid was found to be the most abundant (8.88-7.25%) in all the four species followed by aspartic acid (7.83-5.95%). Among the species, the concentration of glutamic and aspartic content was found to be highest in the A. frithi (8.88 & 7.83%). The range of Essential Amino Acids (EAAs) viz., leucine (3.95-5.76%), valine (3.11-4.22%), isoleucine (2.29-3.29%), lysine (3.65-4.40%), threonine (2.63-3.71%) and phenylalanine (2.90-4.40%) are found in significant amounts. Both the sulphur containing amino acids (methionine and cysteine) were found in relatively low amounts and varied from 1.27-1.95 and 0.35-0.48 per cent. Glycine, alanine and serine were also available in appreciable amounts with values ranging from 3.09-5.87, 3.87-5.48 and 4.52-4.99 per cent, respectively. In case of sweet amino acids (i.e., alanine & glycine), the highest amount was recorded in B. mori (5.48 & 5.87%) but lowest (3.87 & 3.09%) in A. frithi. Most of the amino acid concentration was found to be the highest in A. frithi followed by A. proylei, C. trifenetrata and B. mori, respectively. Total fatty acid analysis revealed that the highest amount of Saturated Fatty Acids (SFA) and Monounsaturated Fatty Acids (MUFA) were recorded in C. trifenestrata (6.69 & 5.26%) followed by A. proylei (4.43 & 4.28%), B. mori (2.38 & 2.70%) while the lowest SFA and MUFA was registered in A. frithi (0.80 & 0.35%). On the contrary, the highest (8.36%) Polyunsaturated Fatty Acids (PUFA) was evaluated in A. proylei followed by C. trifenestrata (7.90%), B. mori (4.36%) and the least amount (0.39%) was recorded in A. frithi. Altogether, 18 fatty acids were registered in A. frithi which was followed by A. proylei and C. trifenestrata (9 nos.) and B. mori (6 nos.). Linoleic and alpha linolenic acid content (2.48 & 5.88%) were found maximum in the A. proylei followed by C. trifenestrata (2.07 & 5.83%) and B. mori (0.78 & 3.58%) while the least linoleic and alpha linoleic acid (0.25 & 0.14%) was observed in A. frithi. In regards of antioxidant properties, phenol (mg catechol equivalent/g), flavonoid (mg quercetin equivalent/100 g) and antioxidant activity (% DPPH inhibition) were found in all the species and varied from 37.261-92.400, 27.223-35.489 and 35.914-74.587, respectively. Cricula trifenestrata showed the highest phenol and flavonoid content (92.400 mg catechol equivalent/g & 35.489 mg quercetin equivalent/100 g) and which was found to be significantly superior over rest of the species. Antioxidant activity was observed to be the highest in A. frithi (74.587% DPPH inhibition) and least in the C. trifenestrata (35.914% DPPH inhibition). The variability in the concentration of tannin, phytic acid and oxalic acid were ranged from 3.280-6.201 mg tannic acid equivalent/100 g, 2.780-5.238 mg/100 g, 1.762-4.138 mg/100 g, respectively. As regards to anti-nutritional compounds, the highest tannin (mg tannic acid equivalent/100 g), phytic acid (mg/100 g) and oxalic acid (mg/100 g) were observed in B. mori (6.201, 5.238 & 4.138) followed by A. proylei (5.702, 4.510 & 3.572), C. trifenestrata (5.468, 3.304 & 2.819) and A. frithi (3.280, 2.780 & 1.762), respectively. However, the presence of anti-nutritional properties in all four edible insect species were detected much more below the recommended range of 250-500 mg/100 g. Microbial enumeration revealed that total viable counts of B. mori, A. proylei and A. frithi silkworm pupal powders stored under ambient temperature (28 to 32°C) had higher bacterial population (3.331, 3.073 & 3.095 log cfu/g), whereas the least bacterial counts (2.639, 2.520 and 2.564 log cfu/g) of B. mori, A. proylei and A. frithi silkworm were observed when they stored under temperature (-16 to -21°C). Cricula trifenestrata recorded the highest population of bacteria (2.870 log cfu/g) under the temperature (15 to 20°C) and least (2.075 log cfu/g) under the temperature (-16 to -21°C). The highest yeast and mould population (3.102, 3.069, 2.855 & 2.714 log cfu/g) was observed when B. mori, A. proylei A. frithi and C. trifenestrata pupal powder were stored at -16 to -21°C. Microbial enumeration showed that B. mori pupal powder had the highest microbial contamination among the other studied sample. Total viable counts were under the advised limit of fresh minced meat (< 6 log cfu/g, TAC). Through microbial test kits, it was further confirmed the absence of two most common food borne pathogens i.e., Escherichia coli and Salmonella sp. in all the studied sericigenous insect samples.
  • ThesisItemOpen Access
    DIVERSITY, POPULATION DYNAMICS AND MANAGEMENT OF INSECT PESTS OF TEA
    (2023) Rabha, Himadri; Dutta, B. C.
    Diversity study of insect pest complex of tea was carried out at three agroclimatic zones of Assam viz.,Upper Brahmaputra Valley Zone (Jorhat) North Bank Plain Zone (Udalguri) and Lower Brahmaputra Valley Zone (Kokrajhar) during 2019-20, 2020-21 and 2021-22, respectively. Laboratory experiments were carried out at Biocontrol laboratory, Department of Entomology, Assam Agricultural University and at laboratory of Krishi Vigyan Kendra, Udalguri. The field experiment was conducted in the tea garden of Udalguri district during 2021-22. Survey results revealed that a total of 4 mites and 22 different insect species belonging to 7 orders and 19 families were found to be associated with tea as recorded from different locations of Assam. In addition, 7 species of insects were found to be as visitors of the tea ecosystem in different period of time. Moreover, 11 different types of natural enemies were also observed. Among the sucking insect pests, per cent infestation of tea mosquito bug was recorded maximum (43.22 per cent) in Jorhat district. Among defoliator pests, per cent infestation of looper caterpillar was recorded maximum (34.23 per cent) in Udalguri district. Among all the insect and mite pests, tea mosquito bug showed highest degree of infestation in Jorhat i.e., 46.21 per cent whereas in case of red spider mite and looper caterpillar, highest degree of infestation was recorded 54.80 and 46.32 per cent in Udalguri district, respectively. Among all the insect and mite pests recorded during the study, tea mosquito bug, red spider mite and looper caterpillar showed moderate (34-66 per cent) degree of infestation, so they are considered as major pests. During 2019-20, the species richness in Jorhat showed maximum value of 1.50 in defoliator pests. The variation of species richness indices indicated a highest value of 1.54 and 1.50 in Udalguri during 2020-21 and 2021-22 in defoliator pests, respectively. Whereas, in Kokrajhar, the highest value was 1.55 in sucking pests (2020-21) and 1.59 in defoliator pests (2021-22). Shannon- Wiener index revealed that the highest value of 2.21 in defoliator pests in Jorhat (2019-20). During 2020-21, in Udalguri, it was found to be highest in sucking pests with value 2.10 and 2.21 in Kokrajhar, respectively. During 2021-22, Shannon- Wiener index showed highest value of 2.10 in Udalguri district and 2.12 in Kokrajhar district in defoliator insect pests. In terms of Simpson’s diversity index, highest value of 0.87 was recorded in defoliator insect pests in Jorhat district (2019-20). Likewise, during 2020-21, in Udalguri and Kokrajhar district, the highest diversity value of 0.82 and 0.87 were recorded in sucking pests, respectively. During 2021-22, the highest diversity values of 0.86 and 0.87 were recorded in defoliator pests in Udalguri and Kokrajhar, respectively. In Jorhat (2019-20), the maximum number of tea mosquito bug was observed to be 5.9 per bush during the first week of September. The highest population indices record of 20.27 mites per leaf was recorded during third week of November. The maximum number of looper caterpillar was observed to be 4.26 per bush during fourth week of February. Correlation studies between weather parameters and population indices of tea mosquito bug showed significant positive correlation with maximum temperature, minimum temperature, evening relative humidity and rainfall whereas, red spider mite showed significant positive correlation with maximum temperature and negative correlation with morning relative humidity, evening relative humidity and total rainfall. The population indices of looper showed significant positive correlation with morning relative humidity. In Udalguri (2020-21), the maximum population indices of tea mosquito bug, red spider mite and looper caterpillar were recorded as 5.12 per bush during the last week of August, 14.78 per leaf during March to April and 5.02 per bush during second week of March, respectively. Correlation studies between weather parameters and population indices of tea mosquito bug showed significant positive correlation with maximum temperature, minimum temperature and evening relative humidity. The population indices of red spider mite showed significant positive correlation with maximum temperature, whereas, it showed negative correlation with morning relative humidity, evening relative humidity and total rainfall. The looper caterpillar population showed negative correlation with maximum temperature, minimum temperature, evening relative humidity and total rainfall. During 2021-22, the maximum population indices of tea mosquito bug, red spider mite and looper caterpillar were recorded to be 5.79 per bush, 28.12 per leaf, 5.23 per bush, respectively. Correlation studies between weather parameters and population indices of tea mosquito bug showed significant positive correlation with maximum temperature, minimum temperature, evening relative humidity and total rainfall. Red spider mite showed significant positive correlation with maximum temperature and negative correlation with total rainfall whereas, looper caterpillar showed significant negative correlation with maximum temperature, minimum temperature and total rainfall. In Kokrajhar (2020-2021), the maximum population indices of tea mosquito bug, red spider mite and looper caterpillar were recorded to be 4.12 per bush, 27.23 per leaf, 4.12 per bush respectively. Correlation studies between weather parameters and population indices of tea mosquito bug showed significant positive correlation with maximum temperature, minimum temperature, evening relative humidity and rainfall, whereas red spider mite showed non-significant positive correlation with maximum temperature and looper showed significant negative correlation with minimum temperature and total rainfall. During 2021-22, the maximum population indices of tea mosquito bug, red spider mite and looper caterpillar were recorded to be 5.30 per bush, 14.52 per leaf and 10.22 per bush, respectively. Correlation studies between weather parameters and population indices of tea mosquito bug showed a negative correlation with morning relative humidity, evening relative humidity and total rainfall. Red spider mite showed significant positive correlation with maximum temperature and negative correlation with morning relative humidity, evening relative humidity and total rainfall whereas looper caterpillar showed significant negative correlation with maximum temperature, minimum temperature, morning relative humidity, evening relative humidity and total rainfall. Laboratory study on efficacy of different plant extracts against tea mosquito bug showed the highest mortality of 80.00 per cent in case of Pongamia pinata in 120 hours after treatment. The results on efficacy of different plant extracts against adult red spider mite showed that the highest mortality was recorded 93.33 per cent in case of both the treatments of Vitex negundo and Azadirachta indica at 120 HAT. Similarly, bio efficacy of different plant extracts against looper caterpillar showed that the larval mortality was highest with value 86.67 per cent at 120 HAT in case of A. indica. The results on efficacy of plant extracts at field condition reveals that at seven days after spraying, P. pinata recorded the least number of populations of tea mosquito bug with 0.67 number per bush. Again, at seven days after spraying, least number of mites was recorded in case of V. negundo with 7.19 mites per leaf. Moreover, the results showed that the maximum reduction of larval population was found in A. indica with 1.72 looper caterpillar population per bush at seven days after spraying.
  • ThesisItemOpen Access
    Combined effect of entomopathogenic fungus with botanicals and insecticides against Helopeltis theivora Waterhouse (HemipteraMiridae)
    (2023) Ray, Sudeshna; Das, Purnima
    The compatibility of a native entomopathogenic fungus, Cordyceps javanica with three different botanicals viz., neem oil, pongamia oil and jatropha oil and insecticides viz., Clothianidin 50 WDG, Thiamethoxam 25 WG and Profenofos 50 EC at three different concentrations viz., recommended dose (RD), half of the recommended dose and more than the recommended dose during 2022-23 in Physiology Laboratory, Department of Entomology, AAU, Jorhat following poison food technique (Nene & Thapliyal, 1978). Results revealed that among all the tested botanicals and insecticides at three different concentrations, half of the RD of each botanical and insecticide exhibited maximum mycelial growth, conidial density and sporulation than RD and more than the RD. Among the botanicals, at half of the RD (0.5%) neem oil showed the lowest inhibition per cent (31.19) followed by pongamia oil (43.58%). However, among the insecticides, at half of the RD (0.01%) Clothianidin 50 WDG exhibited the lowest inhibition per cent (12.84) followed by Thiamethoxam 25 WG (30.50%). The present study also showed varying levels of compatibility of C. javanica with respect to botanicals and insecticides and their doses which could be proved through T toxicity model classification. Among the botanicals, neem and pongamia oils were found to be compatible at half of the RD, with respect to T values which signify toxicity values above 60. Moreover among the insecticides, Clothianidin 50 WDG was found to be compatible with C. Javanica at all three doses (0.01, 0.02 and 0.04%) based on T values whereas Thiamethoxam 25 WG was found to be compatible only at half of the RD and RD (0.01 and 0,02%). The four best compatible combinations i.e. C. javanica (1x 107 conidia ml -1) +Clothianidin 50 WDG (0.01%), C. javanica (1x 107 conidia ml -1) + Thiamethoxam 25 WG (0.01%), C. javanica (1x 107 conidia ml -1) + Neem oil (0.5%) and C. javanica (1x 107 conidia ml-1) + Pongamia oil (0.5%) were tested for their efficacy against H. theivora along with their individual RDs. Results revealed that compatible combinations of EPF and insecticides, C. javanica + Thiamethoxam 25 WG recorded the highest per cent (100) mortality of H. theivora followed by C. javanica +Clothianidin 50 WDG (88%) at 72 HAT as compared to the individual recommended dose of insecticides. Whereas EPF and botanicals, C. javanica + Neem oil recorded 70 per cent mortality of H. theivora followed by C. javanica + Pongamia oil (40%) compared to their individual RDs after 120 hours of treatments. Among all the treatments, less number of feeding punctures per twig were recorded in C. javanica + Thiamethoxam 25 WG treated twigs (20.6 nos.) followed by C. javanica +Clothianidin 50 WDG (25.8 nos.) after 18 hours of treatment, whereas control showed the highest number of punctures (73.8 nos.) at 18 HAT. Moreover, no phytotoxic symptom was recorded by the selected treatments for tea leaves
  • ThesisItemOpen Access
    Efficacy of different essential oils against aphid (Aphis craccivora) in green gram
    (2023) Sonowal, Siranjib; Rajkumari, Prarthna
    Green gram, Vigna radiata (L) Wilczek is a significant pulse crop in India. It offers a protein-rich diet with 211 calories and 14.2 grams of proteins, along with essential minerals, iron and fiber. However, the crop faces production losses due to insect pests, especially aphids, which hinder its early growth stages by continuously sucking cell sap, leading to leaf drying and hampering vegetative growth. The increasing concern over the adverse environmental impact of chemical pesticides has led to the exploration of alternative and eco-friendly pest control measures. Essential oils are a viable alternative to other botanical extracts used as pesticides due to their widespread availability and relative affordability. In this study, we investigated the efficacy of essential oils derived from neem, clove, mint, garlic, ginger and eucalyptus as potential biopesticides against Aphis craccivora Koch, a destructive pest of green gram. The nymph and adult mortality rates were evaluated at different concentrations (1%, 3%, and 5%) after 4, 12, 24, 48 and 72 hours of treatment. Neem oil exhibited the highest nymph mortality of 96.67%, 100%, 100% at 1%, 3% and 5%, respectively. Mint oil also displayed notable efficacy with mortality rates of 73.33%, 73.33%, and 83.33% at 1%, 3%, and 5% concentrations, respectively after 72 hours of treatment. Clove and garlic oils exhibited moderate nymph mortality while eucalyptus oil showed the lowest impact on nymph mortality. All oils demonstrated significantly higher mortality rates compared to the control group. Similar trends were observed in adult mortality rates, with neem oil demonstrating the highest efficacy (56.67% at 1%, 73.33% at 3%, and 76.66% at 5%). Mint oil also exhibited notable adult mortality rates. Conversely, eucalyptus oil showed the lowest mortality rates among all treatments. Furthermore, treatment with essential oils reduced the total development period of A. craccivora compared to the control group, with neem and mint oils resulting in the shortest development periods. The nymphal duration was significantly shorter in the treatment groups, with clove oil exhibiting the shortest 1st nymphal duration. Neem, mint, and garlic oils also contributed to shorter nymphal periods. Additionally, reproductive performance was affected by the treatments, with mint oil resulting in the shortest reproductive period and neem oil leading to the lowest number of offspring produced by a single female. The total number of offspring was significantly lower in the treatment groups, with the control group having the highest number. The importance of essential oils in pest control lies in their eco-friendly and sustainable attributes, offering effective alternatives to harmful chemical pesticides. As we look to the future, further research and development in harnessing the potential of essential oils hold promise for safer and more environmentally conscious pest management strategies.
  • ThesisItemOpen Access
    Exploration of termite mound soil as potting media
    (2023) Kathbaruah, Shiney; Bhattacharyya, Badal
    Laboratory and field experiments were carried out at the Department of Entomology, Soil Laboratory of Advanced Centre for Integrated Farming System Research, Department of Soil Science and at the Experimental Farm, Department of Horticulture, Assam Agricultural University during 2021-2023. During the course of study, seven numbers of potting media using mound soil of a subterranean termite species, Odontotermes obesus were prepared in various combinations with garden soil, sand and FYM and tested along with a control. Experimental analysis as regards to physico-chemical and biological parameters of different potting media revealed superiority of T7 (1 part termite soil + 1 part sand + 2 parts FYM) in terms of soil pH (7.15), organic carbon (2.13%), available nitrogen (526.02 kg ha-1), available phosphorus (56.60 kg ha-1), available potassium (708.19kg ha-1), dehydrogenase enzyme activity (18.21μg TTF g-1 soil 24 hr-1), Phosphomonoesterase (PME) activity (46.68 54μg p-nitrophenol g-1 soil h-1) and urease activity (3.39μg NH4-N g-1 soil 2 hr-1) . Whereas the potting mixture: T4 (2 parts termite soil + 1 part garden soil + 1 part FYM) registered superiority in terms of PME activity (50.54μg p-nitrophenol g-1 soil h-1), Fluorescein diacetate (FDA) activity (11.01μg fluorescein g-1 soil h-1) and Soil Microbial Biomass Carbon (SMBC) (262.25μg g-1). Pearson’s correlation matrix among the physico-chemical and biological parameters showed significant positive correlation in case of soil pH with Electrical Conductivity (EC) (r=0.86, P=0.01), Water Holding Capacity (WHC) (r=0.72, P=0.05), Dehydrogenase activity (r=0.71, p=0.05) and PME activity (r=0.74, P=0.05). Similarly, EC was significantly correlated with WHC (r=0.80, P=0.05), dehydrogenase activity (r=0.73, P=0.05) and PME activity (r=0.76, P=0.05). Significant correlations were observed in case of WHC and PME activity (r=0.72, P=0.05); organic carbon with phosphorus (r=0.97, P=0.01), potassium (r=0.94, P=0.01) and dehydrogenase activity (r=0.86, P=0.01); nitrogen with urease (r=0.87, P=0.01); phosphorus with potassium (r=0.90, P=0.01), dehydrogenase activity (r=0.87, P=0.01), PME activity (r=0.73, P=0.05); potassium with dehydrogenase activity (r=0.78, P=0.05); SMBC with dehydrogenase (r=0.78, P=0.05), PME (r=0.71, P=0.05), FDA activity (r=0.87, P=0.05) and urease activity (r=0.77, P=0.05); dehydrogenase with PME (r=0.80, P=0.05), FDA (r=0.71, P=0.05) and urease (r=0.74, P=0.05) and finally PME with FDA activity (r=0.85, P=0.01). Based on analysis of physico-chemical and biological parameters of different potting media, two potting mixtures (T7 & T4) were selected and their performance was assessed by growing a test crop, Tagetes erecta cv. Inca Orange under pot experiment during November, 2022- March, 2023 in general field conditions. Considering the vegetative parameters of marigold crop, the potting media: T7 was found to be significantly superior in terms of plant spread (39.64 cm) and leaf area index (4.07) over T4 & control. Amongst all the reproductive parameters studied, T7 was found to be significantly superior in terms of fresh weight of flower (37.72 gm), yield of flower (317.81 gm/plant), and flower diameter (9.38 cm) over T4 & control. The B:C ratio of raising marigold flower as potted plant in T7, T4 and control were 1.10, 1.01, and 0.79 respectively whereas the B:C ratio of the potting mixture of T7, T4 and control were 2.52, 1.74 and 1.50 respectively. The outcome of present investigation vividly indicates that the best termite mound soil based potting media (T7 ) can further be explored for commercial cultivation of marigold flower. .
  • ThesisItemOpen Access
    BIOEFFICACY AND DISSIPATION PATTERN OF CHLORANTRANILIPROLE AND JATROPHA OIL AGAINST MAJOR PESTS OF CABBAGE
    (2023) Akhtar, Shahnaz; Choudhury, Kasturi
    The present experiment on ‘Bioefficacy and dissipation pattern of chlorantraniliprole and jatropha oil against major pests of cabbage’ was carried out during 2022-2023. The field experiment was carried out at Experimental Farm, Department of Horticulture and the laboratory experiments were carried at Residue Laboratory, Department of Entomology, Assam Agricultural University, Jorhat and Guwahati Biotech Park, Amingaon. The insecticide and botanical used in the experiment were chlorantraniliprole 18.5 SC and jatropha oil respectively. The insect pests found in field during the period Nov-Jan (2022-2023) were cabbage butterfly (Pieris brassicae), cabbage aphid (Brevicoryne brassicae), cutworm( Agrotis ipsilon), cabbage semilooper ( Trichoplusia ni), white spotted flea beetle( Monolepta signata), head borer ( Hellula undalis) and mustard aphid ( Lipaphis erysimi) and 4 species of coccinellid predators viz., red and yellow colour morphs of Coccinella transversalis, Cheilomenes sexmaculata, Harmonia dimidata and Propylea dissecta. After 1, 3, 5, 7 and 10 days of spraying, chlorantraniliprole 18.5SC @ 0.3ml/l showed maximum percent reduction of lepidopteran pests (90.70 to 92.90) followed by jatropha oil @ 7 ml/l (57.00 to 73.90) and highest infestation was observed in control. In case of Brevicoryne brassicae, the maximum percent reduction was observed in chlorantraniliprole 18.5 SC@ 0.3ml/l (74.40) which was statistically at par with jatropha oil@ 7ml/l (64.00). Chlorantraniliprole and jatroha oil had no significant effect on the population of coccinellid beetles. The highest yield was obtained from chlorantraniliprole 18.5SC @ 0.3ml/l treated plots (302.05 q ha-1), which was statistically at par with jatropha oil @ 7ml/l treated plots (299.15 q ha-1). Benefit cost ratio was also highest in jatropha oil@ 7ml/l treated plots (2.4:1). The lowest yield was obtained in control plot (111.95 q/ha). The initial deposits of chlorantraniliprole 18.5SC at 0 day was 0.44 mg kg-1 followed by 0.30, 0.15 and 0.06 mg kg-1 at 1 day, 3 days and 5 days respectively. The highest dissipation (86.36%) of chlorantraniliprole 18.5SC was recorded 5 days after spraying. The initial deposit of jatropha oil at 3 and 5 ml/l were found below detectable range while the residues of jatropha oil at 7 ml/l could be detectable only at 0 day (1hr) after spraying (0.08mg kg-1). The half-life values calculated were 1.8 days for chlorantraniliprole 18.5 SC @ 0.3 ml/l. The initial deposit of chlorantraniliprole @ 0.3ml/l was found to be below MRL. Therefore, a waiting period of 5-6 days and 1 day for chlorantraniliprole and jatropha oil, respectively has been suggested to avoid any health hazards to the consumers.
  • ThesisItemOpen Access
    BIOEFFICACY OF CERTAIN INSECTICIDES AND PLANT OILS AGAINST MAJOR INSECT PESTS OF CAULIFLOWER
    (2023) G, RAVISHANKAR; Devee, Anjumoni
    Field and laboratory experiments were conducted in the experimental farm, Department of Horticulture, and Biological Control Laboratory, Department of Entomology, Assam Agricultural University, Jorhat during the year 2021-22 and 2022-23. The experiment was conducted to evaluate the efficacy of chlorantraniliprole18.5 SC, thiamethoxam 25 WG, emamectin benzoate 5 SG, neem oil 1500ppm (Check), garlic oil and artemisia oil along with control against major insect pests of cauliflower. The LC50 value was the lowest in chlorantraniliprole followed by thiamethoxam and the highest in artemisia oil. Based on LC50 the order of toxicity to Pieris brassicae after 24 hrs was as chlorantraniliprole (0.063) > thiamethoxam (0.199) > emamectin benzoate (0.435) > garlic oil (4.136) > neem oil (5.122) > artemisia oil (7.702), after 48 hrs it was as chlorantraniliprole (0.044) > thiamethoxam (0.072) > emamectin benzoate (0.116) > garlic oil (3.132) > neem oil (4.308) > artemisia oil (5.858) and after 72 hrs it was chlorantraniliprole (0.028) > thiamethoxam (0.039) > emamectin benzoate (0.056) > garlic oil (1.516) > neem oil (3.368) > artemisia oil (4.057). Similar trend was also observed against Trichoplusia ni with the order of toxicity after 24 hrs was chlorantraniliprole (0.086) > thiamethoxam (0.175) > emamectin benzoate (0.457) > garlic oil (5.694) > neem oil (6.111) > artemisia oil (8.178), after 48 hrs it was as chlorantraniliprole (0.059) > thiamethoxam (0.094) > emamectin benzoate (0.167) > garlic oil (4.072) > neem oil (5.138) > artemisia oil (6.387) and after 72 hrs it was chlorantraniliprole (0.032) > thiamethoxam (0.045) > emamectin benzoate (0.064) > garlic oil (2.337) > neem oil (4.141) > artemisia oil (4.498). The field experiment was done in two seasons, during 2022-23. The first one as midseason (Oct, 2022 - Jan, 2023) and second one as late season (Feb - April, 2023). The treatment garlic oil @5ml/lit of first spray along with chlorantraniliprole 18.5 SC @0.3ml/lit of second spray showed maximum percent reduction of P. brassicae population in both the season (96.72 and 97.00), followed by two sprays of chlorantraniliprole 18.5 SC @0.3ml/lit (94.59 and 93.16), two spray of garlic oil @5ml/lit (90.09 and 87.29) and the lowest population reduction was found in control (17.89 and 19.07) against P. brassicae during first and second season respectively.The maximum population reduction of Trichoplusia ni was observed in garlic oil @5ml/lit of first spray along with chlorantraniliprole 18.5 SC @0.3ml/lit of second spray (96.00 and 95.62) followed by two spray of chlorantraniliprole 18.5 SC @0.3ml/lit (92.10 and 91.35), two spray of garlic oil @5ml/lit (89.00 and 85.24) and lowest reduction was obtained from control (19.16 and 20.55) in both mid and late season cauliflower. In case of aphids, the highest percent population reduction was registered in treatment two spray of garlic oil @5ml/lit (95.60 and 94.40) followed by garlic oil @5ml/lit of first spray along with second spray of chlorantraniliprole 18.5 SC @0.3ml/lit (92.67 and 91.55), neem oil @1ml/lit (85.77 and 83.06) and the lowest reduction was observed in control (8.78 and 18.68) during first and second season respectively. In midseason cauliflower population of Trichoplusia ni was comparatively higher than P. brassicae. In late season cauliflower P. brassicae population was higher than Trichoplusia ni. The garlic oil @5ml/lit, neem oil and chlorantraniliprole showed no significant effects against coccinellid beetles in field conditions. The treatment garlic oil @5ml/lit of first spray along with chlorantraniliprole 18.5 SC @0.3ml/lit of second spray registered the highest mean yield i.e., 171.06q/ha and 168.46q/ha respectively in mid-season and late season crop which was significantly the higher yield than control (93.53q/ha and 91.20q/ha). The highest benefit cost ratio was obtained from the treatment garlic oil @5ml/lit of first spray along with second spray of chlorantraniliprole 18.5 SC @0.3ml/lit (2.43 and 2.89) followed by garlic oil @3ml/lit of first spray along with second spray of chlorantraniliprole 18.5 SC @0.3ml/lit (2.37 and 2.80) and two spray of chlorantraniliprole 18.5 SC @0.3ml/lit (2.33 and 2.75) and the lowest benefit cost ratio was observed in control (1.06 and 1.31) respectively in mid-season and late season cauliflower. The effects of best plant oil i.e., garlic oil @5ml/lit on growth of P. brassicae was also evaluated and observed that garlic oil effect the RGR, RCR and ECI of P. brassicae. The RGR (0.11) and RCR (17.30) was comparatively lower in garlic oil @5ml/lit than control (0.12,18.28, respectively) and they were statistically at par. While the ECI was significantly lower in garlic oil @5ml/lit (5.80) than control (9.24). Garlic oil treated curds were evaluated for their sensory characteristics and found that there was no significant difference between garlic oil @5ml/lit treated curds and control in respect of texture, colour, taste, flavour, odour, appearance, and overall acceptability.
  • ThesisItemOpen Access
    DIVERSITY OF SOIL ARTHROPODS IN POTATO GROWN UNDER DIFFERENT SOIL CONSERVATION PRACTICES
    (2023) Das, Prerana; Bhagawati, Sudhansu
    A field experiment was carried out at the organic plot of Instructional cum Research farm of Assam Agricultural University, Jorhat during December to March, 2022-23, to study the effect of different soil conservation practices on the diversity of soil arthropods in potato. The experiment was conducted with eight treatments which included one conventional Package of Practices for organic cultivation (T1) followed by six different soil conservation practices viz., Minimum tillage + mulching with rice straw @8t/ha (T2), Minimum tillage + mulching with rice straw @10t/ha (T3), Minimum tillage + mulching with rice straw @12t/ha (T4), Zero tillage + mulching with rice straw @ 8t/ha (T5), Zero tillage + mulching with rice straw @ 10t/ha (T6), Zero tillage + mulching with rice straw @ 12t/ha (T7) along with an untreated control (T8). The diversity of soil macroarthropods were studied through pitfall traps, visual observation, bait traps as well as scouting for hand collection whereas microarthropods were extracted through Tullgren Funnel. Data respective to both macro and microarthropods were recorded at pre-treatment and 15, 30, 45, 60 and 75 days after treatment (DAT). Extent of damage of tubers by major soil insect pests under different soil conservation practices was also assessed in both number and weight basis as well as yield and B:C ratio. Experimental results revealed Hymenoptera as the most dominant order (52.22%) among the different soil macroarthropods observed prior to the treatments followed by Araneae (17.23%) and Orthoptera (14.15%). Among the soil microarthropods, the abundance of Collembola and Oribatida were recorded to be 67.61 and 32.39 per cent, respectively in the pre-treated plots. The number of soil macroarthropods was ranged between 53.00 to 58.00/plot prior to the treatments which showed statistical parity with each other. However, a gradual increase in the number of soil macroarthropods was observed at each 15 days interval after treatment as compared to the pretreated plots. Among the treatments, significantly highest number of soil macroarthropods/plot was recorded in T7 plots (66.67, 68.00, 72.67, 342.00, 400.67 numbers at 15, 30, 45, 60 and 75 DAT) as compared to T1 (60.33, 61.67, 62.67, 267.33, 341.00 numbers at 15, 30, 45, 60 and 75 DAT) and T8 (60.67, 62.00, 62.33, 292.67, 362.00 numbers at 15, 30, 45, 60 and 75 DAT), respectively. Soil microarthropods obtained in different plots prior to the treatments was ranged between 625.00 to 722.22 numbers/sq. m. Gradual increase in the number of soil microarthropods was also observed after each interval as compared to the pretreated plots, however, all the treatments did not exhibit any significant (p=0.05) impact on soil microarthropod population during the experimental period. Among different soil conservation practices, the highest infestation of tubers by major soil insect pests was recorded in T7 (7.40% and 17.89%) followed by T4 (7.28% and 16.84%) and T6 (7.20% and 15.13%) whereas the least infestation was recorded in T1 (5.12% and 11.48%) in both weight and number basis, respectively. The total tuber yield was recorded highest in T1 (100.44q/ha) while among the conservation treatments, T7 (99.63 q/ha) recorded maximum yield as well as highest B:C ratio (1.49). In the present study, soil conservation practices showed promising results both in terms of diversity of soil dwelling arthropods and yield of potato. However, proper knowledge on pest status of the cultivating area and their appropriate management strategies may be emphasized for wide spread popularization of the conservation practices among the end-users.
  • ThesisItemOpen Access
    STUDY ON MAJOR INSECT PESTS OF TOMATO AND THEIR ECO-FRIENDLY MANAGEMENT
    (2023) BORA, MAYURAKSHI; Borah, Nirmali
    An experiment entitled “Study on major insect pests of tomato and their eco-friendly management” was conducted at the experimental farm for PG research, Biswanath College of Agriculture, Sonitpur during rabi season of 2022-23. During the present investigation, 11 insect pests from four orders and eight families were recorded as pests of tomato in the field, viz., whitefly, Bemisia tabaci (Gennadius); aphid, Aphis craccivora Koch; leafminer, Lyriomyza trifolii (Burgess); fruitborer, Helicoverpa armigera (Hubner); jassid, Amrasca biguttula biguttula (Ishida); semilooper, Trichoplusia ni (Hubner); epilachna beetle, Henosepilachna vigintioctopunctata (Febricius); flea beetle, Monolepta signata (Olivier); tobacco cutworm, Spodoptera litura (Febricius); cutworm, Agrotis ipsilon (Hufnagel) and green stink bug, Nezara viridula (Linneous). Two coccinellid predators from order coleoptera viz., Micraspis discolor (Fabricius) and Cheilomenes sexmaculata (Febricius) and two spider species Lycosa tista Tikader, Anyphaena accentuata (Walckenaer) were also recorded as natural enemies. Among them B. tabaci, A. craccivora, L. trifolii, H. armigera, A. biguttula biguttula, T. ni, coccinellid predators and spider were found to be most dominant species during the present study. From the correlation study it was observed that aphid population showed a significant negative correlation with both maximum(r = - 0.709**) and minimum temperature(r = -0.511*). Whitefly population registered a negative significant correlation with both maximum(r = -0.745**) and minimum temperature(r = -0.757**) and positive significant correlation with morning relative humidity(r = 0.671**). Jassid exhibited a negative but significant correlation with both maximum(r = -0.782**) and minimum temperature(r = -0.520*). A significant negative correlation was observed between leafminer population and bright sunshine hour(r = - 0.613*). The population of fruit borer registered significant negative relationship with bright sunshine hour(r = -0.674**). Furthermore, cabbage semilooper showed significant negative correlation with maximum temperature(r = -0.611*) and bright sunshine hour(r = -0.542*). As regards coccinellid predators, it showed significant negative correlation with maximum temperature (r = -0.525*), minimum temperature(r = -0.684**) and rainfall(r = - 0.528*) and significant positive correlation with morning relative humidity(r = 0.516*). A significant positive correlation of aphid population was also observed with coccinellid predator population(r = 0.743**). Among the seven treatments tested viz., neem oil @ 5ml/lit, garlic extract @ 5ml/lit, biogreen-L @ 5ml/lit, neem oil @ 5ml/lit + garlic extract @ 5ml/lit, neem oil @ 5ml/lit + biogreen-L @ 5ml/lit, garlic extract @ 5ml/lit + biogreen-L @ 5ml/lit, neem oil @ 5ml/lit + garlic extract @ 5ml/lit + biogreen-L @ 5ml/lit, neem oil @ 5ml/lit + biogreen-L @ 5ml/lit was found to be the best treatment in reducing pests population which was closely followed by neem oil @ 5ml/lit + garlic extracts @ 5ml/lit. Neem oil @ 5ml/lit + biogreen-L @ 5ml/lit treated plot showed the best result in reducing the per cent infestation of leafminer and fruit borer. The highest yield (299.56 q/ha) was obtained from the plot treated with neem oil @ 5ml/lit + biogreen-L @ 5ml/lit with a benefit cost ratio of 3.91. The natural enemy (coccinellid) population was found to be more in neem oil @ 5ml/lit treated plots.