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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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2022 - 20233
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Subject: Genetics and Plant Breeding × Start date: 2016 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    GENETIC VARIATION AND NATURE OF GENE ACTION IN ASSAM RICE FOR GRAIN ZINC CONCENTRATION AND BIOFORTIFICATION POTENTIAL
    (2023) Bhuyan, Nabajyoti; Pathak, Prasanna K.
    The cultivated gene pool of rice is deficient in most of the required micronutrients. Zinc is one of the most important among these to mention about. Twenty (20) percent of the world population is at risk of Zn deficiency resulting from inadequate dietary Zn intake that causes stunted growth (Brown et al., 2009). Genetic and agronomic manipulations for biofortification to raise the concentration of the nutrients in the grain are suggested to overcome the problem. The present investigation was undertaken to study genetic diversity for grain Zn in Assam rice germplasm and also to explore the possibility of bifortification potential. A set of 29 ahu genotypes randomly collected from different places along with the high yielding sali rice variety Shraboni, known to be rich in Zn, were evaluated in 4 different micro-environments created by differential application of Zn fertilizer in ahu season of 2019. Among these, 6 were randomly selected for combining ability studies through diallel mating system without the reciprocals. Observations were taken on different morphological and quality characters and the recorded data were subjected to different statistical analyses following standard procedures. Out of 30 genotypes, 9 were grouped as low (<20 mg 1000g-1), 12 medium (20-30 mg 1000g-1) and 9 others were grouped as high (>30 mg 1000g-1) grain Zn genotypes as per their grain Zn content. Grain Zn content was found highest (52.35 mg 1000g-1) in Shraboni and lowest (11.73 mg 1000g-1) in Basantabahar. GCV, PCV and heritability were high for grain Zn for the genotypes. Grain Zn showed a significant positive correlation with panicle length, grains per panicle and spikelet fertility. Highest grain Zn was recorded in the environment which had relatively high initial soil Zn and was then further added with fertilizer Zn while the lowest grain Zn was recorded in the environment which had low initial soil Zn and no further Zn was added with Zn fertilizer. However, increase in grain Zn with the addition of fertilizer Zn was not uniform across the tested genotypes. The genotypes - Shraboni, Dehangi, Kopouguni, Laishanka and Negilai recorded high grain Zn content across all the environments. Inglongkiri, Panimudi, Arpang and Ranga Ahu showed good grain Zn content in low Zn environment while Begungutia, Kolong, Disang and Ikhajoy showed good grain Zn content in high Zn environment. The results suggest the possibility of identifying high Zn genotypes and also the possibility of agronomic biofortification as most of the genotypes showed increase in grain Zn with addition of external Zn to soil. The genotypes exhibited significant variation in the individual environments as well as over environments for most of the characters studied including yield and grain Fe. Based on D2 analyses the genotypes were grouped in 5 different clusters of which 4 were mono-genotypic and the rest one was with 26 genotypes. Significant variation among the genotypes as well as tested environments was also reflected in the stability analysis. Shraboni, Dikhow and Rangadaria for grain yield and Shraboni, Dehangi, Kopouguni, Laishanka and Negilai for grain Zn showed high mean performance with average stability. There is significant variation among the crosses both in low and high Zn environments for almost all the characters. Significant positive GCA effects were found for grain yield and grain Zn for Inglongkiri and Kolong in both high and low Zn environments. Heterosis over mid parent was seen for grain Zn in Kasalath×Inglongkiri and for grain yield in Kasalath×Ikhojoy and Ikhajoy×Kolong. Heterobeltiosis was recorded for grain Zn in Kasalath×Kolong in high Zn environment.
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    ThesisItemOpen Access
    MORPHO-MOLECULAR PROFILING OF INDUCED VISIBLE MUTANTS OF JOHA RICE (ORYZA SATIVA L.) FOR sd1 AND BADH 2 GENES AND THEIR PHENOTYPIC STABILITY
    (2023) Dutta, Lonishree; Sarma, Kishore Kumar
    Mutation breeding offers a simple, fast and efficient way to rectify major defects without altering their original identity. The present study deployed radiation (gamma rays @ 200 and 300Gy)-induced mutation for the improvement traditional aromatic rice landraces namely Kon Joha. Among the various putative mutants identified in the M 2 generation, only sixtysix rice mutants were advanced to M3 generation. In the present study 28 mutants of Kon Joha from M3 generation were raised in M4 generation along with their parents and four checks for evaluations based on 16 agro-morphological and 9 grain quality traits. Interestingly, all the mutants showed a reduction in plant height as compared to their parents in all the three generations. The reduction in plant height varies from 35 to 45% . Furthermore, mutants of Kon Joha have increased their yield potential over their parents. Interestingly, JKOJM-300-1007-14(3.5 ton/ha) and JKOJM-200-1512-1 (3.2 ton/ha) exhibited the highest yield advantages over their parents. Study on DUS characterization showed variability among the cultivars studied, showing monomorphism for 33 traits and polymorphism for 23 traits. Thus, the phenotypic characterization of the aromatic cultivars established distinctiveness for their utilization in breeding programmes. UNJ clustering based on usual Euclidean distances for the polymorphic traits grouped the cultivars into four multi-genotypic clusters. Further, a pooled analysis of variance based on a randomized complete block design revealed ample variations among the genotypes for the studied traits. The differences observed between genotypic and phenotypic coefficients of variation were low for days to 50% flowering, days to maturity, culm height (cm), culm length (cm), thousand-grain weight (g) and grain yield per hectare (kg), which facilitate selection in the presence of sufficient genetic variability for the traits studied. Mahalanobis D2 analysis revealed three multi-genotypic and one mono-genotypic clusters of the cultivars. Moreover, in the association analysis, grain yield plant -1 is significantly and positively correlated both at genotypic and phenotypic levels with culm height, culm length, panicle length, filled grains panicle-1, chaffy panicle, spikelet fertility, straw yield plant -1 , biological yield plant-1 and harvest index. JKOJM-300-186-14 exhibited the highest amylose 13.05 and highest crude protein was exhibited by JKOJM-200-1512-1 (8.65). The aroma score of the Kon Joha mutants were higher than the checks like Kon Joha, Keteki Joha, Badshah Bhog and Kola Joha. As per sensory evaluation JKOJM-300-158-11, Kon Joha mutant has the overall acceptability. The SSR marker-based genome similarity in rice mutants and corresponding parents ranged from 98.91 to 93.48% indicating the trueness of the mutants. Moreover, the UPGMA algorithm and Gower distance-based dendrogram, neighbour joining tree and PCA scatter diagram assured that mutants were grouped with their respective parents and fell into separate clusters showing high similarity between mutants and parents and dissimilarity among the checks. Three genotypes were identified for nitrogen responsiveness. There was absence of sd1 gene in the mutants. Therefore, it can be concluded that some other genes are responsible for dwarf varieties. BADH2 gene was present in all the genotypes. Four mutants along with four checks were send for multi-location trial . Eberhart and Russel model found JKOJM-300-584-5 (Xi = 3141.9, bi = 1.01 and S2di=0.02) followed by JKOJM-300-158-11 (Xi = 3131.1, bi = 1.04 and S2di=0.09), JKOJM-300-1353-8 (Xi = 2987.29, bi = 1.11 and S2di=0.15) JKOJM-300-1007-14 (Xi = 2845.76, bi = 0.97 and S2di=0.03) exhibited stability under all the environment. Shukla’s stability model also concluded JKOJM-300-584-5 as the most stable genotype. Two-dimensional GGE biplot was generated using the first two principal components (axis 1 and axis 2), which accounted for 69.9% and 18.04 % difference in GEI for yield per hectare, respectively. Locations were found to be the most significant causes of yield heterogeneity, accounting for 75.73 % of overall G + E + G × E variation, respectively, according to the combined study of variance. All the GGE biplots for the grain yield revealed G3 (JKOJM-300-1007-14) as the most stable genotype. AMMI 1 biplot for GYH indicated that G1, G4, G2 and G3 as the high yield genotypes however, only G1 and G3 can be considered as the stable genotypes among them. AMMI 2 biplot was also analysed which revealed that the G8 (E2), G5 (E2), G7 (E6, E5), G6 (E5), G2 (E7, E3) and G4 (E7 and E3) as the high yielding genotypes for GYH for the mentioned environments. Based on ideal genotype ranking genotype G2 followed by G1 was the best performer, with a high mean yield and high stability in the tested environment. According to the AEC line, genotypes G2 and G4 were extremely stable with a high average yielding per hectare. Overall, the information and materials generated from the current study will be very useful and informative for students, researchers and plant breeders. Additionally, our results also showed that irradiation could generate a considerable amount of genetic variability and provide new avenues for crop improvement and diversification.
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    ThesisItemOpen Access
    GENETIC ASSESSMENT FOR WEED SUPPRESSIVE ABILITY AND VESICULAR ARBUSCULAR MYCORRHIZA (VAM) ASSOCIATION OF RICE (Oryza sativa L.) CULTIVARS IN ORGANIC CULTURE CONDITION
    (2022) Roy, Swapan Deb; Borgohain, Rupam
    Rice cultivation in direct seeded condition encounter a lot weed pressure as compared to wet condition leading to considerable yield loss. Organic direct seeded rice face two major constraints in the early growth stage viz. profound weed competition and poor soil nutrient availability due to non-application of inorganic fertilizers. This makes the situation challenging because of lower production. Development of a weed suppressive variety coupled with higher Vesicular Arbuscular Mycorrhiza (VAM) colonization in the root might be a wholesome approach to mitigate the overall weed problem, water scarcity and poor nutritional status of direct seeded organic production system. An effort was made in the present investigation to study the genetic variability with respect to weed suppressive ability and VAM colonization rate among 50 rice genotypes grown by the farmers in the north eastern India. The genotypes comprised of Jhum, Ahu and Sali cultivars (including joha, bora and bao rice). Attempt was also made to elucidate the inter relationships among different morphological traits contributing to weed suppressive ability and VAM colonization. Path coefficient analysis was used to study the direct and indirect effects of different morphological characters on weed suppressive ability and VAM colonization. Half diallel analysis was carried out to study the gene effects of the two characters and identification of parental genotypes having good combining ability and suitable cross combinations. To assess the weed suppressive ability and VAM response, experiments were carried out in the field condition (in Weedy and weed-free environments) and pots (in VAM inoculated soil and control environments) respectively. The yield loss of the genotypes due to weed infestation ranged from 15.08% (cultivar Inglongkiri) to 73.03% (cultivar Jhummalati). The decline in harvest index due to weed pressure was also observed in some genotypes though there was no coherence in harvest index decline and loss in yield. Marked variation was observed in root zone VAM colonization (measured as % of root colonization) among the genotypes which ranged from 53.5% in Garumalati to 10.5% in Rongadoria. The effect of VAM on the growth of rice genotypes was found to be positive and was reflected by the increased values of some quantitative characters. Among the plant characters positively affected by the VAM, root volume (increased by 8.55%) was the maximum followed by grain yield (7.88%) and straw yield (7.55%) whereas there was no effect of VAM on days to 50% flowering, and days to maturity of the cultivars. The weed suppressive ability of the genotypes (WSA) as measured in term of weed competitive index (WCI) was found to be affected positively by seedling growth rate (r=0.71), seedling vigour index (r=0.71), flag leaf area (r=0.67), number of leaves per panicle (r=0.70), number of effective tiller per plant (r=0.71), harvest index (r=0.74), Grain per panicle (r=0.44) and specific leaf area (r=0.36). Plant characters that were found to have positive correlation with VAM response were number of leaves/panicle (r=0.41), specific leaf area (r=0.31) and grain per panicle (r=0.34). VAM response was however negatively correlated with days for maturity (r=- 0.48), leaf area index (r=-0.35) and root dry weight (r=-0.53). The plant characters having a direct effect on WSA were found to be straw weight (1.13), harvest index (1.31), specific leaf area (0.20), seedling growth rate (0.17), days for maturity (0.31). VAM response had direct effect from number of leaves/plant (0.81), grain number/panicle (1.12), grain yield (0.43) and root volume (0.64) but was affected negatively by seedling growth rate (-0.48), root weight (-0.77) and days for maturity (- 0.01).Based on the response of the cultivars on WAS and VAM response 7 parent cultivars were selected and crossed by half diallele mating design to obtain 21 different F1s. The genotypes along with their parents were evaluated for assessment of their combining ability and nature of gene action contributing to characters WSA and VAM response. Four parents, Inglongkiri (3.49), Adhuma (1.88), Maiborok (1.34) and Rongadoria (1.34) had positive GCA effect for WCI but three parents Garumalati (- 1.16), Jhummalati (-0.76), and Begunagutia (-1.58) showed significant negative GCA effect. Out of the 21 crosses seven crossed genotypes had significant positive effect on WCI and nine crosses had shown negative but significant effect for WCI while, rest five crosses had no significant SCA effect. The genotypes Garumalati (2.80), Inglongkiri (11.83) and Maiborok (4.71) showed significant positive effect for VAM response, while the remaining four parents had showed significant negative GCA effect for root colonization. The SCA effect was positively significant for seven crosses, negatively significant for four crosses and ten crosses showed no significant SCA effect for root mycorrhization. For most of the traits studied including WCI and VAM root colonization, higher magnitude of SCA variance was found compared to GCA variance i.e. GCA/SCA variance ratio was less than unity indicating the predominance dominance variance and non additive gene action. Genotypes Inglongkiri, Garumalati, Maiborok Adhuma and crosses Garumalati X Adhuma, Inglongkiri X Maiborok, Adhuma X Inglongkiri were found to be most promising for future breeding programs for Weed Suppressive ability and VAM responsiveness.