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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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2014 - 20183
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Subject: Plant Breeding × End date: 2018 × Type: Thesis × Thesis Type: Ph.D ×
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Now showing 1 - 3 of 3
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    ThesisItemOpen Access
    Genetics of adaptive traits in rice (Oryza sativa L.) under aerobic condition
    (AAU, Jorhat, 2018) Ojah, Hrishikesh; Talukdar, P.
    An investigation on genetic improvement of rice had been taken up to study the performance of few genotypes, their heterosis and combining ability, character association and nature of gene action under aerobic condition. The experiment was carried out at the experimental field of Sarat Chandra Sinha College of Agriculture, Assam Agricultural University, Dhubri during 2015 and 2016 spanning over four seasons. Evaluation of fifteen rice genotypes comprising ten traditional cultivars and five high yielding varieties both in aerobic and irrigated lowland situations revealed sufficient variability and interaction of the genotypes with the environment. Combining ability analysis in Line x Tester design involving 10 lines of traditional upland genotypes and 5 testers of HYV, revealed importance of both additive and dominance effects. Three lines (Banglami, Nagina 22 and Tamdao) and three testers (Luit, IR 36 and Gopinath) were identified as good general combiner, while six crosses were identified with specific combining ability (SCA) effect for higher number of characters. Days to anthesis, days to maturity, plant height and height growth rate were found to have significant SCA and heterobeltiosis in favourable direction in higher number of crosses. Four crosses viz. Aus Jaria/ IR 36, Kasalath/IR 36, Dimrow/KMJ-13A-6-1-2 and Tamdao/IR36 recorded heterobeltiosis for maximum number of characters (4 each). Significant correlation was observed among mean, heterobeltiosis and SCA for most of the characters. Genetic parameters estimated in Line x Tester experiment revealed that number of productive tillers, plant height and proline content were highly amenable for improvement, whereas, high genetic variability existed for proline content, root shoot ratio, number of productive tillers and grain yield. Significant correlation with grain yield existed for 3 characters (number of productive tillers, spikelet fertility and chlorophyll content) apart from sufficient inter correlation among various adaptive characters. Path coefficient analysis revealed the highest positive direct effect of root weight (1.65) on grain yield, followed by spikelet fertility (1.43) and plant height (0.92). Harvest index (1.25) through spikelet fertility exerted the highest indirect effect, followed by panicle harvest index (1.07) through spikelet fertility. Generation mean analysis was carried out in three selected crosses viz. Banglami/Luit, Koimurali/Luit and Guni/Gopinath, involving six generations (P¬1, P2, F1, F2, BC1 and BC2). The individual scaling tests were used to test the adequacy of additive dominance model. The gene effects were estimated using three parameter model (joint scaling test) suggested by Cavalli (1952) and six parameter model suggested by Haymen (1958). The analysis of variance among different generations of different crosses revealed significant variation for most of the characters indicating considerable variability in the material studied. All the characters except height growth rate in cross II, recorded significance for at least one of the four individual scaling tests in all the 3 crosses. Estimation of different gene effects and their interactions revealed significant positive additive effect for plant height and height growth rate in all the three crosses. Preponderance of dominance effect in the expression of height growth rate, spikelet fertility, grain yield, harvest index, root weight and root shoot ratio was evident from the significant positive dominance (h) effect in all the three crosses. With respect to interaction effects, all the characters except height growth rate in cross II, exhibited significant interaction effect for one or more epistatic interactions i.e.[i], [j] or [l] in all the three crosses studied. It is evident that for all the yield and other adaptive traits, additive, dominance and interaction effects were present indicating the complex inheritance of the traits under aerobic condition. On the basis of estimation of various parameters under 3 different sets of experiment over 4 seasons, plant height, shoot weight, number of productive tillers, spikelet fertility, proline content, days to antheis and days to maturity were identified as important adaptive traits to be considered for further improvement of aerobic rice.
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    ThesisItemOpen Access
    MORPHOLOGICAL, BIOCHEMICAL AND MOLECULAR CHARACTERIZATION OF BHUT JOLOKIA (Capsicum chinense Jacq.) OF NORTH EAST INDIA
    (AAU, Jorhat, 2018-01) Goswami Phukan, Rumjhum; Borgohain, Rupam
    The Northeast region of India including Assam is considered as original home of the world’s hottest chilli, Bhut Jolokia (Capsicum chinense). In recent years several varietal types of Bhut Jolokia exhibiting considerable variation in plant, fruit and pungency traits has been observed in the farmers’ field. Therefore, an attempt was made to characterise a few accessions of Bhut Jolokia at morphological, biochemical and DNA level to elucidate the extent and nature of genetic variation. Expression profile of few pungency related genes in Bhut Jolokia was also attempted to detect their possible allelic variation in the Bhut Jolokia accessions. A set of 20 Bhut Jolokia (C. chinense) accessions, three Capsicum annum accessions (Krishna Jolokia, bell pepper and Cherry type) and one C. frutescens accession (Mem Jolokia) were analysed using 35 morphological and biochemical characters. Analysis of variance (ANOVA) for quantitative characters revealed considerable genetic variation among the genotypes. Variability and path analysis identified fruits/ plant, fresh fruit weight and photosynthetic rate as important parameters for improvement. Principal component analysis (PCA) isolated eight principal components each comprising of several characters and accounting for 78.36% of the total variability among the accessions. Several seedling, fruit and physiological characters contributed towards total variability of the population. The PCA plots failed to distinguish Bhut Jolokia accessions into distinct clusters despite sufficient diversity among them. Sixteen characters were identified based on their contribution to PCA, as minimum morphological descriptors for preliminary characterization of Bhut Jolokia genotypes. Population structure analysis separated the accessions into Bhut Jolokia and non Bhut Jolokia populations. Majority of the genotypes had > 80% membership coefficients for each specific group. Only Acc-21 (Cherry type) showed genomic admixture indicating gene flow between Bhut Jolokia and non Bhut Jolokia populations. The genetic diversity studies conducted with the use of 51 SSR markers and 40 gene specific markers exhibited a low inbreeding coefficient (FIS=0.147), thereby indicating high heterozygosity among the genotypes. The overall FST value of 0.432 indicated large genetic differentiation between the populations. AMOVA performed between all lines grouped according to structure indicated 43% variation between populations, 20% variation among individuals within populations and 37% variation was due to variation within individuals. Gene expression analysis of 6 genes of the capsaicinoid biosynthetic pathway exhibited that the Capsaicinoid pathway genes studied showed significantly higher expression in Bhut Jolokia (C. chinense) genotypes while very low expression levels were observed in Bell pepper genotype (low-pungent). Amongst these candidate genes, AMT, Pun1, PAL from Phenylpropanoid pathway and BCAT, KAS and ACL from Fatty acid biosynthetic pathway were found to be up-regulated in pungent genotypes especially in the breaker stage (25-35 DAF) of the fruit development. The variations in the pungency level were found to be associated with changes in the expression level of the genes of the biosynthetic pathway.
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    ThesisItemOpen Access
    GENETIC STUDIES ON HEAT TOLERANT TOMATO (Lycopersicon esculentum Mill.) AND THEIR ANDROGENIC RESPONSE TO ANTHER CULTURE
    (AAU, Jorhat, 2014) Das, Reecha T.; Talukdar, Pranab
    The present investigation comprising of parental, F1, F2 and backcross generations of four tomato crosses viz. H7997 x CLN1621E, H7997 x BL337, H7997 x Nagcarlan and H7997 x CLN2366A was conducted at Assam Agricultural University, Jorhat with three objectives- 1) to study the pattern of inheritance and gene effects for yield, yield attributing and physiological characters related to heat tolerance. 2) to study the genotype environment interaction of the generations of the crosses and 3) to study the androgenic ability of tomato lines and their hybrids. The experiment was conducted in three different environments during the offseason and one in the rabi season. Significant variation was revealed among the crosses and generations for almost all the yield and yield attributing and physiological characters. The pooled analysis of variance indicated profound influence of the environments on the expression of all the characters except for days from flowering to fruit setting. High estimates of genotypic coefficient of variation (GCV) was observed for fruit yield per plant and relative stress injury in most of the environments. High heritability with high genetic advance was observed for number of fruiting clusters per plant, fruit yield per plant, relative stress injury, pollen viability percentage and chlorophyll stability index in two or more environments. Out of the four crosses, high fruit yield per plant was recorded for three crosses viz. H7997 x CLN1621E, H7997 x Nagcarlan and H7997 x CLN2366A all were at par. Pooled analysis of variance for stability revealed significance of linear genotype - environment interaction for all the characters except for days from flowering to fruit setting and number of fruiting clusters per plant. Non linear genotype-environment interaction found to be significant for all the characters except for days from flowering to fruit setting, flower shed percent, chlorophyll stability index and relative stress injury. In the present investigation, the F1 of crosses H7997 x CLN1621E, H7997 x Nagcarlan and H7997 x CLN2366A and F2 of cross H7997 x CLN2366A and B2 of cross H7997 x BL 337 average stability for fruit yield per plant. Correlation studies between stability parameters of yield with yield attributing and physiological characters and also amongst them revealed that stability of and number of fruits per plant among the yield attributing characters and membrane stability percentage and chlorophyll stability index among the physiological characters together with plasticity of rest of the characters was mainly responsible for yield stability in heat tolerant tomato. F1 of cross H7997 x CLN1621E exhibited consistently significant mid parent heterosis over environments for most of the characters including fruit yield per plant. This was followed by crosses H7997 x Nagcarlan and H7997 x CLN2366A. Inheritance studies indicated failure of additive-dominance model for all yield and yield attributing and physiological characters In general, additive effect was found to be predominant in most of the yield attributing and physiological characters in almost all the crosses in two to three environments. Response of the components of generation mean to environmental fluctuations revealed that additive gene effect was consistent for number of primary branches per plant, days from flowering to fruit setting, number of fruiting clusters per plant and number of fruits per plant. Among physiological characters additive effects were found to be consistent for senescence index, lipid peroxidation and relative stress injury. Both additive and non additive gene effect was found to be consistent for fruit yield per plant. Duplicate epistasis was observed for most of the characters under study including fruit yield per plant. However, complementary epistasis was observed for days to fruit maturity, number of fruiting clusters per plant and fruit yield per plant in one to two crosses in individual environments. Androgenic studies revealed that H7997 x CLN 2366A and H7997 x Nagcarlan were the most responsive genotypes with high callus induction percentage and callus diameter. Thus there is also scope for development of doubled haploids in these two crosses.