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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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End date: 2018 × Start date: 2018 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    PHYSIOLOGICAL, BEHAVIOURAL AND MOLECULAR CHANGES IN PIGLETS IN RESPONSE TO WEANING STRESS
    (College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, 2018-07) TIGGA, GLORIA; Dutta, Arup
    The present experiment was conducted to study the effect of weaning stress on various physiological, biochemical, hormonal, hematological response including behavioural changes and pattern of gene expression profile of HSP27, HSP70 and HSP 90 in piglets weaned at different age. The present investigation was carried out in Hampshire x Ghungroo cross-bred piglets of instructional farm of NRC on pig, Rani. Three litters of six piglets were taken for the study and were weaned at different age of 28 days (Gr-I), 35 days (Gr-II) and at 42 days (Gr-III). Blood collection was scheduled from the day of weaning (0d) , 7th day, 15day followed by subsequent collections at 15 days interval up to six months of age. Physiological and behavioural studies were done at the piggery farm and molecular studies were done in the laboratory of NRC on pig, Rani whereas biochemical, hormonal and hematological studies were conducted in the laboratory of the department of Biochemistry, Nuclear research laboratory of the department of Physiology and in the laboratory of Teaching Veterinary Clinical Complex of C.V.Sc., Khanapara, Guwahati respectively. No significant difference was found in average growth rate and body weight at maturity among the groups. There was significant difference in rectal temperature (day 30, 45 and 60) and respiration rate (day 0 and 15) found between Gr-I and Gr-II. The mean heart rate (beats/ minute) was found towards decreasing trend in all the groups. The level of biochemical indices were found to be varied within normal range on day 15 post-weaning and the variations in the level in later part were found to be associated with hormonal level and age related. Higher level of phosphorus was found in piglets of Gr-III as compared to Gr-I and Gr-II. During the initial phase of experimental period significantly lower level of iron was found in piglets of Gr-I as compared to Gr-II (day 15 and 30) and Gr-III (day 0 and 15). Significantly higher level (P<0.001) of zinc was found in Gr-III as compared to Gr-I and Gr-II from day 75 onwards. Significantly lower level of copper was found in Gr-II as compared to Gr-I and Gr-III on day 15 and 30 which may be the cause of subnormal hemoglobin level (%) in this group during this period. The range of cortisol level was comparatively higher throughout the experimental period. Significant differences (p<0.001) were found in the level of hematological parameters viz TEC, Hb% and PCV between younger and older pigs on day 0 to 45. Significantly higher level of neutrophils and cortisol were observed in younger piglets. Initially, there was increase in neutrophil (%) and decrease in lymphocyte (%) indicating a stress response on day 15 post-weaning in all the groups, with significantly higher level in Gr-I. The mean values of DLC viz. neutrophil (%) (day 15, 30, 45, 60, 75, 90) and lymphocyte (%) (day 30, 45, 60, 75, 90) were found to be significantly higher and lower respectively in Gr-I as compared to Gr-II. Significantly higher number of feeding bouts (P<0.05) and higher level of aggression (P<0.05) on d+2 and d+7 was observed in Gr-III compared to Gr-I and Gr- II The level of mRNA expression of HSPs viz; HSP27, HSP70 and HSP90 were found to be increased significantly (P<0.001) on day 7 in piglets of Gr-I. Significantly higher level of mRNA of HSP90 was expressed in Gr-I on day 15 as compared to piglets of Gr-II and Gr-III` indicating that adaptive process were slower in younger piglets.
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    ThesisItemOpen Access
    TECHNOLOGY UPSCALING OF CERTAIN TRADITIONAL PORK PRODUCTS OF NAGALAND
    (College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, 2018-12) SANGTAM, H. MOAAKUM; Laskar, S. K.
    Traditional pork products of Nagaland prepared with locally available plant based ingredients viz. Anishi, Silam and FDS (Fermented dried soya) were evaluated in the present study. Based on the popularity, a purposive survey was conducted in field level to evaluate the level of ingredients used and with an aim to refine and upscale the processing steps and to extend the shelf life of the products. Three formulations were prepared using pork with Anishi, Silam and FDS along with a control, prepared without adding the above ingredients. On the basis of pilot study, the level of incorporation for Anishi, Silam and FDS were selected as 5, 10 and 5 percent, respectively. The cooked products were packaged under two different systems viz. retort pouch and vacuum packaging. The retort pouched products were subjected to physicochemical, microbiological and sensory evaluation at ambient temperature (25-32oC) for 6 months whereas, the vacuum packaged products were evaluated at refrigeration temperature (4±1oC) for 15 days. The economics of products were also calculated. Under retort processing, the total heating time (min) was recorded to be highest in pork with FDS compared to control, pork with Anishi and Silam. The proximate composition i.e. percent moisture, crude protein, ether extract and total ash in retort pouch and vacuum packaging revealed highly significant (p<0.01) differences in control and the treated products. The pork with FDS revealed highest protein content in both retort and vacuum packaging. However, no significant differences were observed for different storage periods. For mean scores of pH, TBARS and tyrosine values highly significant (p<0.01) differences were observed among control and different product formulations and also during different storage periods. The TPC, coliform and yeast and mould were absent under retort pouch packaging during the entire storage period, conversely under vacuum packaging highly significant differences (p<0.01) were recorded in respect of TPC and psychrophilic count among control and all the treated products and at different storage periods. Coliform count was <3 and yeast and mould were absent in vacuum packaged products. The amino acid content in control and treated products were decreased with the increase in storage period. Highly significant (p<0.01) differences were observed in texture profile among control and the treated products as well as during different storage periods under retort pouch packaging. In respect of vacuum packaging significant (p<0.05) differences were observed during different storage periods among control and the treated products. Highly significant (p<0.01) differences were observed in colour profile under retort pouch and vacuum packaging in control and among the treated products and during storage period. The sensory evaluation showed highly significant (p<0.01) differences in appearance, flavour, juiciness, tenderness and overall acceptability in control and treated products and during storage period under retort pouch and vacuum packaging and revealed higher scores in pork with Silam and FDS compared to Anishi and control. The costs of productions were lower in all treated products compared to control under retort pouch and vacuum packaging. Based on the results obtained in the study it might be concluded that traditional pork products could be prepared economically by incorporating traditional ingredients like Anishi, Silam and FDS at 5, 10 and 5 percent levels using vacuum and retort packaging without any appreciable depreciation in nutritive values and sensory qualities till 15 days for vacuum packaging with refrigeration storage and for retort packaging till 180 days under ambient temperature.
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    ThesisItemOpen Access
    EVALUATION OF TWILL WEAVE FABRICS MADE OF BLENDED ERI-MODAL AND ERIACRYLIC YARNS SUITABLE FOR DIFFERENT DRESS DESIGNS
    (AAU, Jorhat, 2018-06) Boruah, Sunita; Kalita, Binita Baishya
    Dress designing has always been an important art and a well- designed garment has beauty and appropriateness, which makes it right for the wearer. To achieve a good fit, it is necessary to give attention to finer details such as fabric structure, individual proportion and contours. In textiles, fabrics are manufactured in wide varieties and designs which are produced by different weaving techniques that enhance the look of aesthetic value of the apparels. Union fabrics are those, where fabrics are created with warp of one kind of yarn and weft of another yarn or blended yarn in one direction or both warp and weft direction of different blended yarn. Weaving of such fabrics has opened a new era with limitless possibilities in the field of textile, as well as in fashion world. The review of the literature suggested that there is an increased interest in blending of silk with other fibres but limited work has been done regarding blending of eri silk with modal and acrylic on commercial spinning system. Therefore, the investigation was carried out to “Evaluation of twill weaves fabrics made of blended eri-modal and eri-acrylic yarns suitable for different dress designs” with the objectives to blend the yarns in different proportions using selected fibres, to analyse the physical properties of selected fibres and yarns, to construct the union fabrics of different twill weaves using selected yarns, to assess the mechanical, comfort and tactile properties of woven fabrics, to design and construct different dresses based on the fabric properties and to take opinion on constructed dresses. The study was limited in three different types of fibres- eri silk, modal and acrylic and three blend proportions were selected, 30:70, 50:50 and70:30.The weaves were limited to only twill weave and derivatives of twill i.e. herringbone and diamond. The present study was conducted to analyze the physical and mechanical characteristics of fibre. The count and diameter of eri silk fiber were higher than modal and acrylic fiber. Whiteness index and the Initial Modulus were found to be highest in modal and lowest in eri-silk. Fibre density and moisture content observed maximum in eri silk followed by modal and acrylic. The tenacity and specific work of rupture of acrylic fibre was greater than modal and eri silk fibre. The results indicated that elongation per cent for eri silk is higher as compared to modal and acrylic fibre. Six developed yarns with varying proportions and one definite count (1/30s) with Z twist were prepared. From the study it was found that the physical and mechanical properties of yarn samples of both the controlled and blended were significant at 5% level of significance and all the samples were found to be different with each other. The developed twill, herringbone and diamond weaves woven fabrics were analyzed for physical, mechanical and comfort properties. Interaction among all the tested samples, the highest fabric count and cloth cover factor were observed in EA 30:70 with diamond weave in both direction. The fabric weight and thickness of all the controlled samples were in increasing trend as compared to union fabrics. Regarding the interaction between all the test fabrics in both the way i.e. warp and weft way controlled eri silk with diamond fabrics was exhibited highest mean value in stiffness, drape co-efficient and dimensional stability. Maximum mean value of flexural rigidity was observed in sample EM 30:70 and the crease recovery angle of all the test samples in both warp and weft direction was seen in sample EA 30:70 with twill weave.The highest wicking height in both the warp and weft direction was observed in controlled modal with diamond weave. Among all the test fabrics, EA 30:70 were exhibited highest values of tensile strength and loss in mass in warp and weft-way. The modal test fabrics with twill weave showing increase trend of air permeability and thermal conductivity. The maximum mean value of thermal insulation was observed in sample controlled acrylic with diamond weave. Subjective evaluations of union fabrics were done by 100 respondents to assess the fabrics visual inspection like appearance, lustre, handle, texture and suitability of products prepared from union fabrics. Respondent opined that all the woven samples have good appearance, soft in hand and smooth in texture. It was observed that cent percent of respondents found eri-modal blended union fabrics with three weaves were high in lustre. The rank order of preferences for the constructed dresses were evaluated by the respondents and it was interesting to note that the rank order of preferences for selection of dress designs and the constructed dresses were found to be similar. The costs of blended yarn were got reduced in comparison to that of 100 per cent eri-silk yarn and it was also observed that the cost of blended union fabrics of different proportion that got reduced in comparison to that of controlled eri silk fabrics.
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    ThesisItemOpen Access
    PERCEPTION OF PARENTS AND ADOLESCENTS ON PARENTING: A SOCIOCULTURAL STUDY
    (AAU, Jorhat, 2018-03) Begum, Toslima Sultana; Phukan, Minoti
    Parenting is defined as purposeful activities aimed at ensuring the survival and development of children. A better understanding on parenting may be achieved when one can understand how adolescents perceived their parents’ involvement in their upbringing. Children’s perception of parenting are better predictor of their behaviour and psychological development (Buri, 1989 and Paulson, 1994). Again parents and young people can hold quite divergent perception of parenting (Smetena, 1995). Thus a study on “Perception of parents and adolescents on parenting: a sociocultural study” was undertaken in Barpeta district of Lower Assam. Sample comprised of 200 adolescents and their parents. To make the sample representative equal numbers of boys and girls from both rural and urban areas were selected. Adolescents under the age group of 16 to 17 years and who lived with their biological parents were selected for the study. The tools designed was a parenting style questionnaire comprising of 32 items in four parenting styles as subscale .A semi-structured interview schedule consisting of statements pertaining to the objectives of the study was also designed. To collect socioeconomic status and back ground information of the respondent a questionnaire by O.P. Aggrawal was used. Results revealed that Majority of the respondents were follower of Hinduism and belonged to OBC/General category. Majority of the respondents belonged to the nuclear type of family system. Most of the respondent family had their monthly income in the range of Rs. 5,000 to Rs. 9,999 and were belonged to lower middle class families. Rural and urban respondents were not significantly different with respect to their overall socio-economic status. Regarding the perception on parenting style, parents perceived their parenting style as authoritative parenting style with highest mean scores of 33.68 and standard deviation 5.03 followed by authoritarian parenting style (mean= 29.2, SD =5.681). Same as their parents adolescents perceived their parents parenting style as authoritative parenting style with highest mean scores of 33.22 and standard deviation 4.79 followed by authoritarian parenting style (mean= 28.81, SD =5.4). No significant difference was found between urban and rural adolescents in relation to their perception of four types of parents’ parenting styles i.e. authoritative parenting style, authoritarian parenting style, permissive parenting style and uninvolved parenting style. No significant difference was also observed between rural and urban parents in relation to their perception on all four types of parenting styles i.e. authoritative parenting style, authoritarian parenting style, permissive parenting style and uninvolved parenting style. Family income and occupation had positive relationship with authoritative parenting style as perceived by parents and adolescents and negatively associated with parents’ education, number of siblings and overall socio economic status of the family. Perceived authoritarian parenting style by both parents and adolescents had positive relationship with income, occupation, education of parents and number of siblings and overall socio-economic status of the family. No significant gender difference was observed in adolescents’ perception on their parents’ parenting styles and in-between perception of boy’s parents’ parenting style and girl’s parents’ parenting style. Most of the rural and urban parent’s perceived problems in different aspects of parenting which creates stressed on them. Most of the adolescents also had perception on their parents’ problem in parenting them. Developing a parenting module and creation of awareness programmes on different aspects of parenting adolescents inconsideration with contemporary parenting style adopted by parents is needed for both rural and urban parents.
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    ThesisItemOpen Access
    MORPHO-BIOCHEMICAL STUDIES OF TEZPUR LITCHI
    (AAU, Jorhat, 2018-07) GOGOI, SUKANYA; Kotoky), U.
    A study was conducted on different varieties of litchi (Litchi chinesis Sonn.) at litchi garden, Porua, Tezpur and Experimental Farm, Department of Horticulture, Assam Agricultural University, Jorhat during 2016-2018 to have a “Morpho-biochemical studies of Tezpur litchi”. A total of seven varieties with four replications were laid out in a Completely Randomized Design (CRD). The varieties that were taken for investigation were Bombay, Shahi, Piyaji, China, Bilati and Elaichi from Tezpur and Shahi from Jorhat district. The canopy spread of cultivar T2 (Tezpur Shahi) was the highest (15.80m) and lowest (8.65m) in T7 (Jorhat Shahi). Pyramidal, oblong, spherical and elliptical tree shape was observed among the various cultivars of litchi. During the period of investigation, the cultivar T1 (Bombay) took the lowest duration of flowering (18 days) and the highest was recorded in cultivar T5 (Bilati), i.e., 31.50 days. The duration from flowering to harvesting was highest (92.25 days) in T5 (Bilati) and lowest (81.25 days) in T1 (Bombay). The highest fruit weight of 27.79g was recorded in the cultivar T5 (Bilati) which is followed by T4 (China) cultivar (21.88g) and lowest (13.12g) was recorded in T7 (Jorhat Shahi). The highest fruit length of 3.82cm was recorded in the cultivar T3 (Piyaji) and the lowest fruit length (2.97cm) was in T7 (Jorhat Shahi). Fruit circumference showed significant difference among the cultivars where highest (12.40cm) was recorded in T5 (Bilati) and that of lowest (8.70cm) in T7 (Jorhat Shahi). The highest fruit volume (29cc) was recorded in T5 (Bilati) followed by T4 China (24.50cc). Round, cordate, oblong and oval shapes were noticed among the cultivars. The highest aril weight was observed in case of T5 (18.42g) and the lowest was observed in the cultivar T7 i.e., 9.40g. The highest peel weight (4.98g) was recorded in case of Bilati. The highest (6.42) and the lowest (3.07) aril-peel ratio of were observed in case of the cultivar T2 and T7 respectively. The aril thickness was the highest in case of T5 (0.97cm) and the lowest was recorded in T7 (0.47cm). The highest seed weight (3.69g), length (3cm) and diameter (1.27cm) were recorded in T3 (Piyaji) and the lowest values were recorded in T6 (Elaichi). The highest specific gravity of 1.091 was recorded in the cultivar T5 (Bilati) and the lowest (1.036) in T7 (Jorhat Shahi) though their differences among the varieties were found to be non-significant. The variety T4 (China) recorded the highest yield per hectare (48.47t/ha), whereas, the lowest yield (13.92t/ha) was recorded in T7 (Jorhat Shahi). The data on fruit cracking percentage revealed that, the highest fruit cracking (27.22%) was recorded in cultivars T2 (Tezpur Shahi), followed by T3 (Piyaji) and the lowest (12.56%) was in T5 (Bilati). The highest skin strength of 3.21kgcm-2 was recorded in cultivar T5 (Bilati) and T2 (Tezpur Shahi) was found to have the lowest fruit skin strength of 2.48kgcm-2. The highest fruit skin calcium (5.29mg/100g DW) and highest boron content (0.123mg/100g DW) were found in case of the variety T5 (Bilati) and lowest values were in T7 (Jorhat Shahi). Regarding juice content, the highest (18.46cc) was recorded in T5 (Bilati). The cultivar T5 (Bilati) was recorded to have the highest TSS content of 19.77oBrix and the lowest TSS was in T7 (Jorhat Tezpur). The highest titratable acidity (1.65%) was recorded in the cultivar T7 (Jorhat Shahi). Highest reducing sugar (9.86%) and total sugar 17.33% were recorded in the cultivar T5 (Bilati). The cultivar T5 (Bilati) exhibited the highest Vitamin C content of 63.38mg/100g. The highest potassium content (1270mg/100g) was recorded in T5 (Bilati) which was followed by T1 (1105.75mg/100g). The highest anthocyanin content (39.93mg/100g) was recorded in the cultivar T5 (Bilati), whereas, the highest anthocyanin degradation index (4.07) was recorded in the cultivar T7 (Jorhat Shahi). The highest POD (4870.93U/mg protein) and PPO (89.17U/mg protein) specific activity were recorded in T7 (Jorhat Shahi) and that of the lowest values was observed in T5 (Bilati). The highest DPPH inhibition percentage (69.62%) and highest flavonoid content (65.93mg/100g) were recorded in T5 (Bilati). Physiological loss in weight (4.46%) and browning index (243.77) were lowest in T5 (Bilati). Correlation coefficient analysis revealed significant positive correlation of yield with fruit weight, volume, aril weight and canopy spread. The available soil nutrient content of Tezpur was found to be better than that of Jorhat and from this investigation, it can be concluded that, all the litchi varieties of Tezpur were found superior both in quantitative and qualitative characters.
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    ThesisItemOpen Access
    PURIFICATION, ANTISERA PRODUCTION AND DEVELOPMENT OF DIAGNOSTIC KIT AGAINST POTATO VIRUS Y
    (AAU, Jorhat, 2018-07) Mishra, Ranima; Nath, P. D.
    Purified viral protein of Potato virus Y (PVY) was isolated from PVY culture maintained on potato (Solanum tuberosum L.) plants. The average concentration of the purified protein was found to be 153.1 ng/ μl with an average yield of 0.449 mg virus per gram of fresh plant tissue. Presence of flexuous filamentous virus particles with an average length of 590 nm in the purified viral suspension was confirmed by Transmission electron microscopy. PVY purified virus preparation was used for immunizing rabbit for production of polyclonal antisera. Good quality antisera were collected one week post boosters (AS4b, AS5b, AS6b and AS7b). The IgG fractions from these four antisera were tested for the detection of PVY by DAS-ELISA with universal anti- rabbit enzyme conjugate as secondary antibody, resulted high specificity with the known PVY infected samples. The assay was compared with the commercial DAS-ELISA kit (Bio Reba, AG, Switzerland). Among the antisera, AS6b was showing the highest mean absorbance value for all positive samples (2.210) which was at par the value shown by the commercial kit (2.250) and these were followed by AS5b (1.680), AS7b (0.929) and AS4b (0.362), respectively. AS6b was showing the highest mean absorbance values for the leaf extracts of samples which were statistically at par with the values shown by the commercial kit. IgG titres for the four batches were measured using a series of IgG dilutions from 10-3 to 10-6 with conjugate and sample dilutions at 10-3 and 100, respectively. Significant differences were observed in the titres of these four batches of IgG at 10-3 dilution. At that dilution, AS6b showed the highest mean absorbance value (1.272) followed by AS5b (1.009), AS7b (0.806) and AS4b (0.522), respectively. In DAS- ELISA with sap dilutions where IgG and conjugate dilutions were constant at 10-3, no significant differences observed in the mean absorbance values of all IgG batches at each sap dilutions and similar trend was observed, among the antisera batches, in sensitivity of IgG towards diluted samples. The AS6b showing the overall highest mean values followed by AS5b and AS7b, respectively. Finally, IgG batch 6b (AS6b) was selected and tested by a simple and rapid tissue/ dot- print immunoassay against PVY. The AS6b showed a highly specific reaction with dot- prints of PVY infected plants at IgG (AS6b) and IgG conjugate dilutions of 10-3. The test was done with sap dilutions of 1:1, 1:2, 1:4, 1:8, 1:16, 1:32 and 1:64 (V/V). AS6b could detect presence of PVY by showing the desired purple coloured reaction up to 1:8 sample dilution. Molecular characterization of PVY from PVY infected samples of Jorhat district, Assam was also carried out through reverse-transcriptase polymerase chain reaction (RT-PCR) assay resulting in desired 328 bp amplicon. Partial sequencing of RT-PCR product and phylogenetic analysis revealed that the virus is closely related to Potato virus Y worldwide isolates.
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    ThesisItemOpen Access
    GENETIC DIVERSITY IN BANANA (Musa spp.) GERMPLASM OF ASSAM
    (AAU, Jorhat, 2018) Baruah, Sudeshna; Kotoky, U.
    An experiment was conducted at the Experimental Farm, Department of Horticulture, Assam Agricultural University, Jorhat to evaluate the huge diversity among the banana germplasm commonly available in the state of Assam. The experiment was laid out in Randomized Block Design with five replications the evaluation was done based on agro-biochemical parameters as well as the genetic diversity present within the genotypes using SSR markers. Based on growth, yield and fruit biochemical characters, the genotypes were clustered with respect to Euclidean distance and also by Trocher’s method. These clusters showed significant differences as compared to the genomic classification of banana. The genotypes were found to show significant diversity based on all the characters and considering all the variations, there were four major clusters found within the 24 genotypes under this investigation. The diploid balbisiana genotypes (Bhimkal and Athiakal) were found to occur in two different solitary clusters, whereas both the culinary genotypes (Kachkal green and white types) consisted a single cluster. The characters like pseudostem height, leaf area, planting to shooting interval, shooting to harvesting interval, crop duration, number of fingers per bunch, fruit weight, fruit volume, number of seeds, pulp: peel ratio, sugar content were found to show high GCV, PCV added with very high heritability and high genetic advance and therefore, these characters were identified to be subjected to improvement by direct selection. After the molecular study using 52 primers, a total of 32 primers were found to produce reproducible bands and 197 alleles were detected by them, of which 170 were polymorphic bands. Percent polymorphism thus obtained was 84.95%. The average polymorphism information content of the primers was 0.437, which was the highest for primer 41(0.913). In the study, a few molecular identities for different genotypes could be identified. A single band sized 400bp, specific to ‘Digjowa’ genotype was found with the SSR27. For both the red bananas considered in the study (Agnisagar and Gobin Tulsi), another specific band sized 250bp was identified with SSR22. The Jaccard’s similarity index was calculated using the molecular marker data and the average similarity index was found to be 0.552, which suggested sufficient diversity present within the genotypes. The maximum similarity based on this was found between ‘Manjahaji, and ‘Barjahaji’. Based on this similarity index, another clustering was done which found two major clusters within the 24 genotypes. In cluster 1, there were two subclusters and in cluster 2, there were three sub-clusters followed by a single genotype (‘Fesa Manohar’). This study had revealed that even among the genotypes belonging to same genomic group, there is sufficient differences based on agro-biochemical parameters and genetic information they carry. Moreover, from this study, the promising genotypes for different characters could be identified on the basis of growth, yield and fruit biochemical characters. Further, on the basis of the present study, efforts can be made for inclusion of more number of primers for even better characterization of the genotypic variability, detailed study for pest and disease resistance and more specifically by including gene specific primers.
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    ThesisItemOpen Access
    DYNAMICS OF ZINC FRACTIONS AND AVAILABLE NUTRIENTS AS INFLUENCED BY ZINC FERTILIZATION ON RICE CULTIVARS
    (AAU, Jorhat, 2018-07) Baishya, Bhupen Kumar; Basumatary, A.
    A field experiment was carried out at the Instructional-cum-Research (ICR) farm, Assam Agricultural University, Jorhat during Kharif season, 2014 and 2015 to study the influence of zinc fertilization on the dynamics of zinc fractions, available nutrients status in the soil and crop yield and quality of rice grain of different cultivars. The treatments consisted of zinc applied through soil with or without foliar spray and five different rice cultivars. Total of twenty treatment combinations were laid out in factorial RBD with three replications. Distribution of different zinc fractions in soil were assessed during different stages of crop period of rice. Perusal of experimental findings showed that zinc fertilization exerted a significant positive effect on different zinc fractions in the soil during both the years of investigation. Among zinc treatments, concentration of all the zinc fractions were maximum with application of Zn @ 5 kg ha-1 + 0.5% foliar spray of Zn over other treatments. The study revealed that the concentration of the water soluble plus exchangeable Zn, complexed-Zn and crystalline sesquioxide bound-Zn fractions showed a decreasing trend from tillering stage to the harvest stage of the crop, while, availability of amorphous sesquioxide bound Zn, residual-Zn and total-Zn fractions followed an increasing trend with respect to concentration with the advancement of time. Among the zinc fractions, water soluble plus exchangeable form made the lowest contribution while residual fraction made the highest contribution to the total zinc pool than other fractions of Zn at all the growth stages of the crop. At harvest, zinc concentration in various fractions of Zn in soil varied in the following order: watersoluble plus exchangeable < complexed < crystalline sesquioxide bound < amorphous sesquioxide bound < residual fraction< total zinc. There was significant positive correlation among the Zn fraction in soil indicating existence of dynamic equilibrium of Zn in soil. The available fraction of all nutrients was initially higher and gradually decreased with advancement of crop growth. The maximum availability was obtained at tillering stage and thereafter as crop age advanced nutrient availability decreased. Analysis of pooled data revealed that application of Zn @ 5 kg ha-1 in soil + 0.5% foliar spray resulted in higher availability of nitrogen, potassium, sulphur and DTPAZn in soil at different stages of crop and recorded highly significant and positive correlation with different zinc fractions. Availability of phosphorus, DTPA-Fe, DTPAMn and DTPA-Cu were decreased with zinc application and the lowest content was found at treatment Zn @ 5 kg ha-1 in soil + 0.5% foliar spray and exhibited a significant but inverse correlation with different zinc fractions. Zinc fertilization influenced the crop yield and nutrient uptake. Highest grain yield was recorded in treatment receiving Zn @ 5 kg ha-1 + 0.5% foliar spray of Zn (53.40 q ha-1) and the lowest was in control (38.69 q ha-1). Among the cultivars, variety JKRH-401 recorded the highest grain yield (64.27 q ha-1) whereas variety Kolajoha recorded the lowest grain yield (30.50 q ha-1). Among different treatment combinations, application of Zn @ 5 kg ha-1 + 0.5% foliar spray of Zn in combination with cultivar JKRH-401 recorded the highest yield (71.82 q ha-1) . The highest straw yield was recorded in treatment receiving Zn @ 5 kg ha-1 + 0.5% foliar spray of Zn. Among the cultivars, the highest straw was recorded in JKRH-401(71.22q ha-1) while, the lowest was found in Aghunibora(49.27 q ha-1). Uptake of nitrogen, potassium, magnesium and sulphur by rice was significantly influenced by Zn-fertilization and the highest was found in treatment with treatment receiving Zn @ 5 kg ha-1 and 0.5% foliar sprays of Zn over other treatments. On the other hand, in respect of copper and manganese, application Zn @ 5 kg ha-1 and 0.5% foliar spray of Zn resulted the lowest uptake during all crop growth period. The cultivars, JKRH-401 recorded the highest uptake of all the nutrients at all stages of crop growth. In economic terms, combined application of Zn @ 5 kg per ha and 0.5% foliar spray of Zn in combination with cultivars, JKRH- 401 recorded the highest gross return, net return and B:C ratio (2.96 ). Zinc fertilization had significant impact on the nutrient content in both brown and polished rice grains. The treatment receiving Zn @ 5 kg ha-1 + 0.5% foliar spray of Zn recorded the highest concentration of nitrogen, potassium, sulphur and zinc for both brown and polished rice. Protein content was found to be the highest in treatment receiving Zn @ 5 kg ha-1 + 0.5% foliar spray of Zn and cultivar JKRH-401 exhibited the highest content of 10.71 % and 8.75 % in brown and polished rice, respectively. Highest amylase content (18.73 % and 20.42 %) was observed in same treatment and the cultivar Kolajoha recorded the highest amylase of 22.52 % and 24.16% in brown and polished rice, respectively.
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    ThesisItemOpen Access
    A study on the role of exopolysaccharide in conferring acid tolerance in Bacillus sp.
    (AAU, Jorhat, 2018-01) Deka, Priyadarshini; Barooah, Madhumita
    Soil bacteria have evolved various mechanisms to adapt to stress environmental conditions such as temperature, salinity, drought and low pH condition of soil. Among the several environmental stress conditions, soil acidity an important factor influencing physicochemical and biological properties of soil along with microbial diversity and crop production is an emerging issue of immense concern due to its wide spread distribution across the globe. Although low soil pH restricts the number and diversity of bacteria, it is known that some soil bacteria are able to thrive in such conditions having evolved various mechanisms including production of biofilm to circumvent acid stress. Bacterial exopolysaccharide (EPS) are high-molecular-weight complex polymers composed of sugar moieties that form the main component of the biofilm which aid the bacteria to colonize substrata. In the present study, a total of 28 isolates were identified and characterized as acid tolerant EPS producing bacteria among which, B. amyloliquefaciens p16 produce the highest EPS (219.96 μg/ml). A culture medium containing sucrose (3.5%) as carbon source with pH 5.0 and incubated for 24 hrs was optimal for maximum production of EPS. The HPLC analysis of monomeric units of EPS produced by B. amyloliquefaciens p16 revealed the abundance of galactose at pH 7.0 which however, changed to arabinose when shifted to acidic condition (pH to 5.0 and 4.5). The isolate B. amyloliquefaciens p16, significantly improved soil physical properties in terms of greater soil aggregation (80.59 mm diameter aggregates) and water holding capacity (53.90%) when inoculated into soil over the control (31 mm diameter aggregates and 18.21%, respectively). The differential expression of epsA and epsB, the first two genes of the eps operon showed a 7 and 9 fold increased expression in pH 5.0 compared to pH 7.0 respectively. Disruption of the epsB gene in B. amyloliquefaciens p16 using integration vector pMUTIN4 generated mutants that produced significantly lesser EPS (33.23 μg/ml) when compared to the WT (223.87 μg/ml). The generated mutant of B. amyloliquefaciens p16 lacking the wrinkled morphology had an extended lag phase of 24 hrs and was barely able to survive in acidic medium (pH 4.5) unlike that of the WT type. Soil inoculated with generated mutants formed smaller soil aggregates (42.41±1.70 mm) and had decreased water holding capacity (27.67±1.94%) compared to the WT (80.59± 0.22 mm and 53.90± 1.66%, respectively). This study indicates that EPS secreted by acid tolerant bacteria (B. amyloliquefaciens p16) imparts acid tolerance and also aids in improving the soil physical structure through increased soil aggregation and water holding capacity.