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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
    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.
  • ThesisItemOpen Access
    Exploration of Jasmonic Acid induced resistance in Chilli (Capsicum annuum Linnaeus) against Aphid (Aphis gossypii Glover)
    (2023) KUMAR, MADEVU SAI; Borkataki, Shimantini
    The present investigation on evaluation of Jasmonic acid induced resistance in chilli (Capsicum annuum Linnaeus) against aphid (Aphis gossypii Glover) was carried out in the Insectary under BARC project of Department of Entomology, AAU, Jorhat during 2022-23. During the course of study, two experimental sets were established (Set A and Set B) with five treatments viz., T1 (JA @ 0.1 mM), T2 (JA @ 0.5 mM), T3 (JA @ 1 mM), T4 (JA @ 1.5 mM) and T5 (control). Experiments were initiated when single spraying was done at 20 DAT in Set A and two sprayings were done at 20 and 60 DAT in Set B. The plants were treated with JA to activate induced resistance. Results revealed that the aphid count (per 10 cm terminal shoot) was reduced in Set B as compared to Set A contributing to the fact that in both the experimental sets the plants recovered from aphid stress induced by foliar sprays of JA. A gradual decrease in the number of aphids per 10 cm terminal shoot was recorded from day to day observation after sprays in T1, T2, T3 and T4 whereas gradual increase followed by decrease in number of aphids was observed in T5. The lowest number of aphids per 10 cm terminal shoot was found in T3 (1.75±2.06 numbers) on 15th day after release of aphids followed by T4 (3.50±2.89 numbers) whereas the highest was recorded in T5 (27.50±1.29 numbers). Similar trend in aphid count was also observed in Set B where the lowest number was observed in T3 (3.75±1.26 numbers) on 10th day after release of aphids and highest was recorded in T5 (35.50±2.06 numbers) after second spray. Significant variation was also observed among the treatments. Comparative analysis on plant growth parameters was carried out in both the sets of experiments. The highest total chlorophyll content was measured in T3 (2.39±0.06 mg/g) under Set B as compared to T3 (1.55±0.07 mg/g) under Set A. The lowest was recorded in T5 (0.61±0.04 mg/g and 1.60±0.04 mg/g) in both the sets A & B respectively. The highest per cent relative leaf water content was measured in T3 (72.60±3.79 %) under Set B as compared to T3 (66.52±3.41%) in Set A. Significant negative correlation was observed between number of aphids, total chlorophyll and relative leaf water content in both the sets at p≤0.05. Analysis on plant growth parameters were carried out in both the sets of experiments. Results revealed that T4 showed the highest plant height (54.13±2.90 cm) whereas T5 showed the lowest plant height (33.63±1.42 cm) in Set A. Similar results were also recorded in Set B where the highest plant height (55.88±2.17 cm) was observed in T4 and the lowest plant height (35.63±0.95 cm) was found in control T5. A substantial increase in plant height was recorded in Set B after second spray where the highest plant height (175.88±4.33 cm) was observed in T4 (JA @1.5 mM) and lowest plant height (152.38±2.81 cm) was found in T5. Reproductive growth represented by the number of flowers also increased significantly with increase in concentration. Highest number of flowers was observed in T4 (80.75±2.63) whereas lowest was observed in T5 (61.25±2.87) under Set A. Comparatively, a significant increase in the number of flowers was observed in T4 (123.75±2.75) in Set B. Results revealed T4 to be the best treatment with yield/plant being 478.25 g and mean weight of fruits being 119.56±4.18 g in Set A. However, increase in yield/plant (691.00 g) and mean weight of fruits/treatment (172.75±2.74 g) was observed in T4 under Set B. The outcome of present investigation vividly indicated that T4 can further be explored for commercial cultivation of chilli for increased yield and production and T3 for protection against insect pest attack by inducing resistance as Jasmonic acid (JA), a plant signaling substance, has a noteworthy reputation in inducing resistance (IR) against insect herbivory.
  • ThesisItemOpen Access
    EFFICACY OF PLANT OILS AGAINST MAJOR INSECT PESTS OF BRINJAL
    (2023) Sarmah, Krishna; Devee, Anjumoni
    The present experiment was carried out to evaluate the efficacy of plant oils against major insect pests of brinjal at the Biological Control Laboratory, Department of Entomology and the experimental farm, Department of Horticulture, Assam Agricultural University, Jorhat during 2022-2023. For the laboratory experiment, the treatments considered were eucalyptus oil, karanj oil, garlic oil, artemisia oil, black pepper oil, neem oil and chlorantraniliprole 18.5 SC. Chlorantraniliprole 18.5 SC was found to be the most toxic with LC50 values of 0.42%, 0.05% and 0.01% at 24, 48 and 72 hours, respectively. Among the plant oils, garlic recorded the lowest LC50 values of 8.45%, 3.70% and 1.20% at 24, 48 and 72 hours, respectively. Karanj oil was the least effective with the highest LC50 values of 15.70%, 13.36% and 8.39% at 24, 48 and 72 hours. Relative toxicity studies showed that 72 hours after treatment, chlorantraniliprole, garlic oil and eucalyptus oil were 382.00, 3.18 and 1.21 times more toxic than neem oil whereas, black pepper oil, artemisia oil and karanj oil were 0.60, 0.50 and 0.45 times less toxic than neem oil, which was used as a standard check. Under field conditions, 10 different insect pests were observed throughout the growing period of the brinjal crop namely, brinjal fruit and shoot borer (Leucinodes orbonalis), aphids (Aphis gossypii and Myzus persicae), whitefly (Bemisia tabacci), white spottedflea beetle (Monolepta signata), crucifer flea beetle (Phyllotreta cruciferae), semi-looper (Trichoplusia ni), Eressa confinis, epilachna beetle (Epilachna vigintioctopunctata) and jassids (Amrasca biguttula biguttula). Additionally, 5 different species of coccinellid predators viz., Cheilomenes sexmaculatus, Brumoides suturalis, Coccinella transversalis, Micraspis discolor and Cheilomenes propinqua were also recorded.10 days after the first spray, an initial decrease in shoot infestation was observed, where chlorantraniliprole 18.5 SC recorded the lowest number of infested shoots (0.33) followed by garlic oil @ 5 ml/l (1.08) and eucalyptus oil @ 5 ml/l (1.58). The highest infestation was observed in control (4.25). 15 days after the first spray, there was a gradual increase in infestation, hence, a second spray was carried out after an interval of 5 days. 20 days after the second spray, it was observed that the highest infestation was in control (4.83). Additionally, a decrease in the overall population was observed and the lowest number of fruit infestation was observed in chlorantraniliprole 18.5 SC (0.16) with 92.62 per cent reduction, followed by garlic oil @ 5 ml/l with a reduction of 73.81 per cent. After second spray, the lowest number of aphid population (2.25) was observed in garlic oil @ 5 ml/l with a reduction percentage of 81.69 at 20 days after spraying. Chlorantraniliprole 18.5 SC, garlic oil @ 5 ml/l and eucalyptus oil @ 5 ml/l had no significant effect on the population of coccinellids. After the application of the different concentrations of plant oil in the brinjal crop, phytotoxicity studies were carried out at an interval of 1, 3, 7, 10 and 14 days. There has been no observation of phytotoxic symptoms in the brinjal plant. Further studies on yield parameters revealed that the highest yield was obtained from chlorantraniliprole 18.5 SC (200 q/ha) treated plots, which was statistically at par with garlic oil @ 5 ml/l (190.02 q/ha) treated plots. The highest benefit cost ratio was also recorded in garlic oil @ 5 ml/l (1.1:84) after chlorantraniliprole 18.5 SC treated plots while the lowest yield (117.66 q/ha) was obtained in untreated control. Sensory evaluation tests after cooking indicated that no significant difference was observed between control, garlic oil @ 5 ml/l and eucalyptus oil @ 5 ml/l treated brinjal with respect to texture, colour, taste, flavour, odour, appearance, and overall acceptability.