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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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20173
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Subject: Crop Physiology × End date: 2019 × Start date: 2016 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    TAPPING OF CARBON DIOXIDE IN RICE ECOSYSTEM THROUGH AZOLLA CULTIVATION
    (AAU, Jorhat, 2017-07) Khwairakpam, Rowndel; Das, Ranjan
    The present investigation was carried out in the stress physiology laboratory under fully automated bioreactor where tapping of CO2 and external injection regulation CO2 facility were available. To understand the assimilation and N accumulation in Azolla-Rice ecosystem in response elevated CO2 possible interactions of CO2 and Azolla on the growth and yield of rice investigation was conducted during the kharif season of 2014 and 2015.The studies revealed that there was variable response of photosynthetic parameters which lead to impact on carbon sequestration potential as well as change in O2 evolution under varying levels of CO2 environment under rice-Azolla ecosystem. In case of fluorescence and related parameters, there was deviation from the normal range as the CO2 concentration increased, however these deviations were minimized in presence of Azolla. These were also same in case of ETR, NPQ, PQ, ф PSII etc. Photosynthetic and its related parameters viz. gs, Ci, T, etc. were found to be related to stomatal density and size. These factors ultimately affected plant growth which was translated as yield. Elevated (500 ppm) CO2 with Azolla has a greater potential for C sequestration, while soil organic carbon enhancement helped increase crop productivity and sustainability which was evident from higher yield and yield attributing parameters. Soil microbial population with higher C: N ratio was recorded under elevated CO2 with rice-Azolla ecosystem. There have been increasing concerns regarding the role of soil microbial population in biological stabilization of SOC in agricultural soils because change in the soil microbial population within rhizo-spheres with changes in organic matter input. Significant reduction of NPK was recorded due to elevated CO2, however; reduction rate was variable with Azolla when compared with without Azolla and ambient. Conversion of inorganic nitrogen was significantly reduced in elevated CO2 however there was amelioration affect under 500 ppm CO2 with Azolla due to significant increase in key enzymes such NR, NiR and GS syntheses activity. CO2 enrichment decreased the N concentration in rice without any change in the C content, leading to an increase in C:N ratio However variability among systems also recorded. This study: (1) depicts the changes in microbial population and fungal predominance; (2) infers a biological stabilizing mechanism behind the C sequestration which includes physical-chemical stabilization as the major controlling processes leading to variation of yield. Azolla has enormous potential to sequester of atmospheric CO2 due to its rapid growth in freshwater without the need for a soil-based nitrogen source. Azolla is a novel opportunity to expand and diversify the supply of fertilizers and production of rice fields vis a vis tapping the CO2 and enhancing the O2 evolution system under changed environmental conditions.
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    ThesisItemOpen Access
    PHYSIOLOGICAL CHARACTERIZATION OF SOME WHEAT GENOTYPES FOR HIGHER NITROGEN USE EFFICIENCY AND YIELD POTENTIAL IN ASSAM
    (AAU, Jorhat, 2017-09) Chack, Sonbeer; Bharali, B.
    Wheat is one of the most important cereal crops globally, and is a staple food for about one-third of the world’s population (Hussain et al., 2002). Nitrogen is the most important yield-limiting nutrient for crop production in the world (Huber and Thompson, 2007). Two field experiments were conducted for two consecutive years near Stress Physiology Laboratory, Department of Crop Physiology, Assam Agricultural University. The main objective of the study was to characterise some wheat genotypes (collected from East Zone of India) physiologically for higher nitrogen use efficiency (NUE) and yield potential in Assam. In the first year experiment (November, 2014-April, 2015): Nitrogen @ 0, 50, 100, 150 kg ha-1 (as Urea) in the form of granules @ 50% of N as basal with the whole recommended doses of P (as Single super phosphate) and K (as Muriate of potash), and the rest 50% Urea were applied at maximum tillering stage. In the second year experiment (November, 2015-April, 2016), Nitrogen @ 0, 500, 1000, 1500 ppm (equivalent to granules in kg ha-1) were applied as foliar spray at the maximum tillering stage (once in a week for two weeks) of the crop. In the first year experiment, the varieties having the higher NUE in leaves were Wheat 231 (11.36%)> HP 1744 (8.58%)> Pusa Gold (8.42%), and higher NUE in seed were Wheat 231 (19.41%)> HP 1744 (10.01%)> Pusa Gold (9.29%)> PBW 343 (8.27%)> HD 2967 (6.08%). The physiological parameters contributing to the higher NUE in the varieties were maximum Leaf area in Wheat 231(16.81, 17.55 cm2 plant-1)> HD 2967 (15.11, 16.98 cm2 plant-1) at maximum tillering and PI stages respectively. The maximum leaf number was observed in wheat 231 (23.27)> HP 1744 (21.53)> PBW 343 (19.43) under the highest dose of N i.e. 150 kg ha-1 at panicle initiation stage. The other physiological parameters viz. root length of Wheat 231 (12.77 cm)>Pusa Gold (12.57 cm), root volume of Wheat 231 (10.31 cc)> PBW 343 (8.43 cc), and shoot dry weight of Wheat 231 (1.66 g)> HP 1744 (1.55 g) were responsive to augment NUE in the wheat varieties. The variety Wheat 231 (36.18, 34.26)> HP 1744 (33.19, 33.60) showed the highest NR activity (nmol NO2- g-1 fw of leaf) at both Maximum tillering and PI stages. Wheat 231 also exhibited higher N contents in leaf (0.41%) at PI stage, in grain (0.61%), and in leaf (0.37%) at harvest. The yield and yield attributes for higher NUE in the variety Wheat 231 were number of seed spike-1 (48.73), spike length (12.72 cm), spike weight (4.01 g), test weight (45.67), economical yield (3.02 t ha-1) and harvest index (47.32%). Nitrogen @ 150 kg ha-1 imparted higher NUE in leaves (12.48%) and grain (15.79%). In this contest, the physiological & biochemical parameters were leaf number (22.45), leaf area (18.30 cm2), root volume (8.41cc), NR activity (34.08 nmol NO2- g-1 fw of leaf) at PI stage, and starch content in leaf (271.05 mg g-1 d.w.) at maximum tillering stage, total N uptake (37.50%) and N content in seed & leaf (0.46%, 0.38%) at harvest as compared to values in controlled one. In the second year experiment, the varieties having the higher NUE in leaves were of Wheat 231 (10.90%)> HP 1744 (8.15%); and in case of seed, it was in Wheat 231 (18.74%) only. The physiological parameters contributing to the higher NUE in the variety Wheat 231 were: maximum leaf area (15.29 cm2 plant-1) at PI stage; root length (14.66 cm) at PI stage, NR activity (37.40 nmol NO2- g-1 fw hr-1) at maximum tillering stage, nitrogen content in leaf (0.456%) at PI stage and starch content in leaf (221.20, 241.22 mg g-1 d.w) at both maximum tillering and PI stages. The yield and yield attributes for higher NUE in the variety Wheat 231 were number of seed spike-1 (46.39), spike length (12.03 cm), test weight (44.00 g), economical yield (2.76 t ha-1) and harvest index (47.07%). The N dose @ 1500 ppm triggered higher NUE in leaves (12.07%) and grains (15.61%) at harvest. In this case, the other physiological & biochemical parameters contributing the higher NUE were leaf area (16.05 cm2), root length (14.39 cm), NR activity (19.08-37.69 nmol NO2- g-1 fw hr-1), N content in seed & leaf (0.493% & 0.394%) at harvest and nitrogen harvest index (0.56%) as compared to values in the controlled one. Overall, in the experiment 1, the variety Wheat 231 possessed the highest score (12) followed by PBW 343 (3)> Pusa Gold (1), and the variety HP 1744 & HD 2967 obtained zero score at harvest. In the second year, too, Wheat 231 (11) scored the highest followed by PBW 343 (3)> Pusa Gold (2)> HP 1744 (1), and the variety HD 2967 obtained zero score at harvest. Thus, it could be concluded that Wheat 231 emerged as the most physiologically efficient variety in the experiments. This variety possesses the adaptive traits, especially the higher NUE, yield and its attributes. Further, N-dose response studies revealed that N @ 150 kg ha-1 (as granule) or N @ 1500 ppm (as foliar spray) in the form of Urea was the most effective in augmenting the NUE and its related physiological indices including economic yield in wheat crop in Assam.
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    ThesisItemOpen Access
    ASSESSMENT OF CROP CONDITION UNDER ABIOTIC STRESS USING REMOTE SENSING TECHNIQUE IN UPLAND RICE CROP
    (AAU, Jorhat, 2017-09) Goswami, Jonali; Das, Ranjan
    The rise of CO2 (600 µmol mol-1 CO2 by the middle of 21st century) will effectively influence the productivity of crop plants. Again nitrogen is a limiting nutrient in most of the agricultural soils. In the present investigation, the responses of local genotypes of rice were studied in Carbondioxide Temperature Gradient Tunnel (CTGT) to simulate elevated CO2 concentration and temperature. Similarly, pot experiment was done at varying levels of nitrogen fertilization. The results revealed that CTGT II had a greater impact on various morpho-physiological parameters and showed a declining trend indicating the deleterious effect of high temperature, at a higher CO2 and temperature in CTGT III, but, some parameters viz. stomatal conductance and transpiration rate were significantly reduced at CTGT II. From the above experiment, it is evident that some degree of tolerance exhibited against high temperature stress which could be attributed to higher accumulation of carbohydrates, proline, adjustment of anatomical features, water status, better defense mechanism particularly in the genotype Inglongkiri followed by Banglami as compared to IET 22238 and Bash under elevated carbondioxide and temperature conditions. Similarly, nitrogenous fertilizer application had a statistically significant effect on yield components of rice genotypes. There was an increase in yield components with increase in each successive level of nitrogen fertilizers. Enhancement of yield components under high nitrogen levels might be attributed to vigorous and healthy growth, higher photosynthetic pigments, improved water relations and the formation of the membrane system of chloroplasts. Among rice genotypes Inglongkiri recorded significantly higher yield components at low nitrogen levels as compared to the Banglami, IET22238 and Bash. Further, it was revealed that hyperspectral remote sensing could effectively be used for detection of varietal performance, nutrient content and other biochemical parameters of the crop. It was observed that few specific bands were sensitive to chlorophyll (704,803 nm), protein (1514nm), nitrogen (2060, 2300nm), Fluorescence (730nm). Apart from specific bands, indices like NDVI, PSSRa, PSRI, FRI were highly correlated to different parameters of the crop. It is observed from regression analysis that yield can be estimated as function of different spectral indices with a R square value more the 0.7 under both the conditions at a statistical significance with 95% confidence level. A GUI has been developed for display and retrieval of information for the target plants which aided in generation of spectral data base to discriminate spectral behavior of commonly grown genotypes of rice in this region.