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Author: Das, Prerana × Start date: 2020 × Type: Thesis ×
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    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.
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    ThesisItemOpen Access
    Strategy for development of stem cell like embryonic fibroblast cells
    (College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2022-09) Das, Prerana; Nath, Nikhil Ch
    Fibroblast cells are the type of cells that play an important role in the formation of connective tissue. The use of fibroblast cell is versatile, for e.g., demonstration of avian viruses, feeder cells, production of vaccines, preservation of genetic resources etc. In this present study, duck embryonic fibroblast cells were isolated, cultured, and sub-cultured up to six passages. The cells were grown in four culture media i.e., Medium 1(MEM), Medium 2(MEM+IGF-1), Medium 3 (MEM+10% FBS), Medium 4 (MEM+10% FBS+IGF-1). In serum and serum-free media the time required for the cells to attain 70% confluence in primary culture was 84.667±.0.152 hours and 111.867±0.161 hours respectively. The cells grown in medium containing serum showed better results than cells grown in serum-free medium. The time taken to reach 70% confluence in 6th passage in Medium 2 and Medium 4 which are IGF-1 supplemented are 94.583±0.217 hours and 62.167±0.096 hours respectively whereas time taken in Medium 1 and Medium 3 which are IGF-1 free media are 95.350±0.039 hours and 62.667±0.152 hours respectively. Therefore, the cells grown in IGF-1 supplemented media showed significant difference compared than the rest of the culture media (p≤0.01). Morphologically, the cells showed characteristic spindle shape, turgor vitalis cytoplasm, centrally located nuclei and flame-like pattern up to the sixth passage. The viability assessment was carried out in first, second, third, fourth, fifth and sixth sub-culture and the viability percentage of the cells in six different sub-cultures were 89.843±0.108, 91.427±0.082, 91.228±0.081, 91.867±0.079, 92.231±0.073, 93.431±0.069 in the case of Medium 1, 90.425± 0.085, 92.358± 0.124, 93.692±0.084, 93.982 ±0.282, 94.625 ±0.089, 94.892 ±0.096 in the case of Medium 2, 89.145 ±0.263, 90.482±0.09, 91.643±0.143, 92.713±0.186, 93.460±0.079, 94.543±0.074 in Medium 3, and 88.597±0.132, 89.387±0.143, 90.552±0.101, 91.423±0.078, 93.077±0.140, 93.077±0.140 in Medium 4. The viability percentage between the passages was significantly different (p≤0.01). However, the viability of the cells was better from the second subculture compared to primary cultures. The pluripotency of the cells was observed by immunostaining using NANOG antibody, a pluripotent marker that is expressed in embryonic stem cells. It was observed that cells showed positive for NANOG at every subculture depicting their pluripotent nature.