Thumbnail Image

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.

Browse

20224
Reset filters
Subject: Plant Pathology × Start date: 2022 × Type: Thesis ×
Reset filters

Search Results

Now showing 1 - 4 of 4
  • Thumbnail Image
    ThesisItemOpen Access
    Role of beneficial bacteria on yield of Calocybe indica and Pleurotus species and management of contaminants in mushroom beds
    (2022) Gogoi, Monuj; Sarmah, D. K.
    Milky (Calocybe indica) and oyster mushroom (Pleurotus spp.) is the mostimportant cultivated mushroom in India and a very less works has been conducted to identified the role of bacteria on growth and yield of mushrooms. Therefore, the aim of present study was to investigate the effective bacterial spp. isolated from cultivated mushroom substrates and their role in mycelial growth, influence of primordia formation, pinhead and yield of mushrooms. Six bacterial cultures were isolated from the growth substrates of Pleurotus spp. and casing soil of Calocybe indica. Out of six bacterial isolates, 3 isolates were observed positive effect on growth and development of mushroom species. The other isolates were inhibiting the mycelial growth of Pleurotus florida, Pleurotus djamor and Calocybe indica. In in vitro experiment was observed that addition of effective single and combine bacterial isolates with pure culture of C. indica, P. florida and P. djamor enhanced the pinhead formation in Petriplate conditions as compared to control. In vitro cultivation of Pleuortus spp., single and combined application of MB1, MB2 and MB5 could enhanached the formation of pinhead, primordia and fruting body as well as increasing the yield of P. florida and P. djamor. In in vivo experiments, combined application of MB1, MB2 and MB5 (T7) isolates were found to be the best treatment to enhances the spawn run, early initiation of pinhead, formation of fruiting body and yield of C. indica and P. florida. In case of P. djamor experiments, the maximum growth and yield parameters were observed in spraying of MB1 @ 30 ml/bed (T1) followed by spraying of MB1, MB2 and MB5 @ 30 ml/bed (T7) to promote the growth and yield parameters of P. djamor over control. The bacterial isolates viz., MB1, MB2 and MB5 were recorded more or less inhibition against the mycelial growth of Trichoderma spp. in in vitro conditions. The maximum mycelial growth inhibition percent (55.44%) was observed in MB2 isolates over control. The highest natural incidence of green mould contamination was observed in all the mushroom species viz., C. indica, P. florida and P. djamor beds in control treatment (without inoculation of bacterial isolates) in in vivo conditions. Based on cultural, morphological, biochemical and molecular analysis, the bacterial isolates viz., MB1, MB2 and MB5 were identified as Pseudomonas flourescens (96.79% homology with KM206793.1), Bacillus cereus (98.01% homology with MG594014.1) and Alcaligenes faecalis (98.26% homology with KY608969.1) respectively. In another experiment, all the effective bacterial isolates were able to produce growth promoting 6 substances like siderophore and IAA.Nutrient contents viz., crude protein, crude fat, crude fiber, ash and carbohydrate of C. indica and P. florida were enhanced by combined addition of effective bacterial isolates to the cultivated substrates over uninoculated control. In the present investigation it was also observed that the combined inoculation of effective bacterial isolates viz., MB1, MB2 and MB5 increased the mineral contents (calcium, sodium, magnesium and potassium) of C. indica and P. florida. In case of P. djamor, mineral contents were maximum in T1 (spraying of MB1 @ 30 ml/bed) followed by T7 (spraying of MB1 + MB2 + MB5 @ 30 ml/bed) as compared to control (T8). The results of present experiments concluded that artificial addition of growth promoting bacterium in growing medium play a crucial role in the early colonization of substrates, initiation of fruting body, yield enhancement and management of green mould contamination of mushrooms.
  • Thumbnail Image
    ThesisItemOpen Access
    Elimination of the Potato Viruses from the Local Landraces through in Vitro Culture
    (2022) Phookan, Jutimala; Kalita, Manoj Kumar
    The present investigation on local landraces of potatoes from Assam was conducted to eliminate the viral infections. For this the local landraces were collected from different districts of Assam viz., Jorhat, Biswanath, Sonitpur, Barpeta, Dibrugarh and Kokrajhar. Different symptoms like puckering of leaves, cupping of leaves, leaf rolling, purple colouration on leaves, calico pattern, mosaic symptoms, crinkling of leaves, etc. were observed. It was observed that the landrace from Barpeta had the highest disease incidence of 62.22 per cent and the lowest incidence of 10.00 per cent was observed in Badami aloo collected from Kokrajhar. PCR analysis of the symptomatic samples showed the presence of different viruses like PVY, PLRV, PVM, PVX, PVS and AMV. The potato tubers were also subjected to PCR analysis and only PLRV was detected with the highest incidence in Barpeta landrace (75.00 %). The growth and yield attributing characters of the landraces collected were also recorded. Plant height was observed to be highest in the landrace of Dibrugarh with 43.36 cm. The highest number of branches was observed in Dibrugarh landrace. The weight of tubers per plant was observed to be highest in case of Dibrugarh landrace (383.48 g). In the in vitro studies, three types of explants (nodal segment, tuber eyes and apical meristem) with two types of media (MS and PM media) were used to conduct the experiment. Among the various hormonal combinations used for shooting, the best hormonal combination observed was 2 mg/ l GA3 + 4mg/ l NAA + 2 mg/ l BAP irrespective of the explant and media used in case of the parameters viz., time required for shooting, number of shoots developed and length of shoots. Similarly in case of rooting the best hormonal combination observed was 1.5 mg/ l IAA + 1.5 mg/ l GA3 + 1.5 mg/ l KIN irrespective of the explant and media used in case of the parameters viz., time required for rooting, number of roots developed and length of roots. The potato plantlets survived highest (86.67 %) when grown from tuber eyes whereas the disease incidence of PLRV was lowest (20.00 %) in case of plantlets grown from apical meristem. Further SAR chemicals were applied exogenously in the potato plants grown in field condition and it was observed that BTH applied at 1.5 mM had the highest reduction of incidence over control (87.03 %). The results of application of SAR chemicals were also supported by the biochemical analysis of DAB assay and PPO assay. On application of thermotherapy, no disease incidence was observed at 40 ⁰C for 2 hours 30 minutes where germination was 50 per cent.
  • Thumbnail Image
    ThesisItemOpen Access
    Molecular epidemiology of viral disease complex of Capsicum chinense Jacq. in North Eastern Region of India
    (2022) Khaba, Chingakham Inao; Nath, P. D.
    Viral disease complex of Capsicum chinense Jacq. were the major constraint facing by king chilli growers in North Eastern Region (NER) of India in recent decades. A total of 94 samples were collected from Assam (36), Arunachal Pradesh (12), Nagaland (10), Meghalaya (8) and Manipur (28). Both DNA & RNA were isolated and detected CMV, PVY, ChiLCV & GBNV. Peculiar symptoms of shoestring, vein banding, leaf puckering, leaf curl and leaf necrosis were observed. Moreover, unknown mix viral infection symptom like yellowing, stunted growth were also observed. Severe symptoms as well as highest vectors population were observed in Assam and lowest in Meghalaya. After PCR base detection, CMV has the highest per cent infection in NER of India (47.88%) followed by PVY (8.58%), ChiLCV (8.34%) and GBNV (4.55%). CMV was detected from all the five states of north east India. The highest disease incidence of CMV was observed in Manipur (53.57%) and lowest in Meghalaya (37.50%). PVY was detected from Assam and Manipur with an incidence of 26.31 and 16.66% respectively. ChiLCV and GBNV were detected from Assam only with an incidence of 26.31 and 16.66% respectively. With respect to altitude, CMV was more prevalent at the mid-altitude (200-800 m a.s.l.) with 54% and followed by low altitude (<200 m a.s.l.) with 48%. The lowest CMV prevalent was at the high altitude (>800 m a.s.l.) with 47%. Whitefly prevalence depending on altitude; at low altitudes (0–200 m), 35% of the plants sampled were colonized by more than five whiteflies and 38% of the plants no whiteflies were detected. Although 49% of the plants sampled at mid-altitude (200–800 m) were not colonized, 33% were colonized by one to five whiteflies, and the remaining 17% by more than five. At high altitudes (>800 m a.s.l), no whiteflies were detected on 92% of the plants. Those mix viral infection of king chilli leaves was done Next Generation Sequencing (NGS) in Illumina platform. A data of 3.75 GB was generated in which 66.2% of chilli genome were mapped. The unmapped read data was 1.4 GB. After Denovo assembly, 51.9 Mb was generated and subjected to BLAST in NCBI. A total of 27 different isolates of king chilly viruses were revealed and 6 viruses were novel in NER of India viz., Pepper cryptic virus, Pepper vein yellows virus, Tomato ringspot virus, Capsicum frutescens endornavirus, Alphaendorna virus and Pepper leafroll virus . The highest occurrence virus was pepper vein yellow virus (10/27) and followed by Pepper cryptic virus (6/27), Capsicum frutescens endornavirus (4/27) and Chilli veinal mottle virus (3/27) respectively. The single occurrence viruses were Tomato ringspot virusT , Potato virus Y, , Pepper leafroll virus and Alphaendorna virus . All the NGS viruses were ranged 87-100 % homology to NCBI database.
  • Thumbnail Image
    ThesisItemOpen Access
    IDENTIFICATION AND CHARACTERIZATION OF BACTERIAL PATHOGENS IN MEDICINAL, AROMATIC AND SPICE PLANTS OF ASSAM
    (AAU, Jorhat, 2022) GOGOI, MOUSUMI; Borah, P K
    Accumulated knowledge of medicinal, aromatic and spice plants from ancient times helps to improve human health and life from generation to generation. There is tremendous scope for the extensive development of these important plants. But different diseases cause considerable loss of these plants that result in substantial economic loss to farmers. Although bacterial diseases cause severe loss to different medicinal, aromatic and spice plants in different states of our country, not much work had been done on bacterial diseases of these crops in Assam including other Northeastern states. Therefore, the present study was made to isolate, characterize and identify some of the bacterial pathogens associated with diseases of medicinal, aromatic and spice plants in Assam. Disease samples from medicinal, aromatic and spice plants viz., Chilli (Capsicum annum), Ginger (Zingiber officinale), Coriander (Coriandrum sativum), Betelvine (Piper betle), Pennywort (Centella asiatica), Giloy (Tinospora cordifolia) and Cardamom (Elettaria cardamomum) were collected from Golaghat, Jorhat, Karbi Anglong and Nagaon district of Assam. On the basis of cultural, morphological and biochemical studies the seven bacterial isolates were identified as genus Xanthomonas (in Chilli, Coriander, Betelvine and Giloy), Pantoea (in Pennywort), Bacillus (in Ginger) and Pseudomonas (in Cardamom). Further molecular characterization and phylogenetic analysis were done to identify the different bacterial isolates i.e., isolate MGH1 GOLAGHAT as Xanthomonas axonopodis pv. vesicatoria (bacterial leaf spot of chilli), isolate MGH2 GOLAGHAT as Bacillus pumilus (rhizome rot of ginger), isolate MGH3 JORHAT as Xanthomonas campestris pv. coriandri (bacterial leaf spot of coriander), isolate MGH4 GOLAGHAT as Xanthomonas axonopodis (bacterial leaf spot of betelvine), isolate MGH5 JORHAT as Pantoea ananatis (bacterial leaf spot of pennywort), isolate MGH6 JORHAT as Xanthomonas campestris (bacterial leaf spot of giloy) and isolate MGH7 JORHAT as Pseudomonas oryzihabitans (bacterial blight of cardamom).