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ThesisItem Open Access EFFECT OF GROWTH REGULATORS ON ASSAM LEMON (Citrus limon L)(2020-07) Bakhtari, Wahedullah; Kotoky, U.An experiment was conducted on Assam Lemon (Citrus limon L.) at the Experimental Farm, Department of Horticulture, Assam Agricultural University, Jorhat during 2018-2019 to study the “Effect of growth regulators on Assam Lemon (Citrus limon L)”. Six treatments with four replications were laid out in a Randomized Block Design. The treatments comprised of GA3 (60, 80 and 100ppm) and NAA (30, 40 and 50ppm). The growth regulators were applied as foliar spray at three growth stages: (1) at pre flowering stage in the month of November, 2018, (2) at flowering stage and (3) one month after fruit set. The plant growth regulators showed significant response on flowering. The minimum number of days (52.67days) was recorded in T2 (GA3 80ppm) from the date of plant growth regulators application and the highest number of days were required in case of T6 treatment (NAA 50ppm). The highest number of flowers per plant (476.74), highest fruit set (81.32%) and the lowest fruit drop (18.50%) was recorded from T2 (GA3 80ppm) during the experiment. Number of fruits per plant was recorded highest in GA2 80ppm (371.33) and the lowest in T6 (NAA 50ppm). The highest fruit weight (136.53g), fruit length (10.00cm), fruit girth (15.93 cm), fruit volume (162.89cc) and yield (52.72 t/ha) were recorded in T2 (GA3 80ppm) while the lowest values were recorded in T6 (NAA 50ppm). The results revealed that, pulp weight and pulp-peel ratio were significantly influenced by growth regulator applications. The highest pulp weight (108.32g) and the highest pulp-peel ratio (4.83) were recorded in T2 (GA3 80ppm). Peel thickness was lowest (0.48cm) in T2 (GA3 80ppm) and the highest of 0.73cm was recorded in T6 (NAA 50ppm).The results revealed that, T2 (GA3 80ppm) took the lowest number of days required for flowering to harvesting (102.47 days) and the highest (133.77 days) in T6 (NAA 50ppm). Regarding the total leaf chlorophyll content, the highest was recorded (1.29mg/g of fresh weight) in T2 (GA3 80ppm). However, there were no significant differences in leaf nitrogen and leaf phosphorous among the treatments. Highest leaf potassium (1.69%) was recorded in T1 (GA3 60ppm). The highest juice content (37.29cc) was recorded in T2 (GA3 80ppm). The highest TSS (5.18°Brix), titrable acidity (3.50%) and TSS-Acidity ratio (1.48) was recorded in T1 (GA3 60ppm), whereas, the lowest values were recorded in T6 (NAA 50ppm). From the results of the ascorbic acid content (32.15mg/100ml) the highest was recorded in T2 (GA3 80ppm). Regarding evaluation of the economics of cultivation, it can be concluded that, the highest benefit-cost ratio of 3.52 was obtained from T2 (GA3 80ppm) followed by 3.44 from T1 (GA3 60ppm). The lowest B:C ratio (2.41) was recorded in T6 (NAA 50ppm). Thus, it can be suggested that, GA3 at 80ppm is the most economical plant growth regulator to improve flowering, yield and quality of Assam Lemon.ThesisItem Open Access COMPARATIVE EVALUATION OF ACARICIDAL PROPERTIES OF Datura stramonium and Datura metel(AAU, Jorhat, 2020) GOSWAMI, MANISHA PRIYAM; Nath, TankeswarTicks are group of arthropod vectors that not only cause disease but also transmit diverse pathogens that affect human and animal health. Indiscriminating use of synthetic acaricides have led to development of acaricide resistance in ticks. Several plant secondary metabolites are known to exhibit toxic affect on insects. Phyto-extracts are also environmentally friendly and have thus become attractive alternative in insect management strategies. Datura has long since been used in folklore medicine and is reported to have other pharmaceutical uses. My research involved the use of two different species of Datura, viz., D. stramonium and D. metel that grow abundantly in the North East India especially, in Assam. The two species of Datura were collected from different locations of Jorhat district and evaluated for their acaricidal properties. Chemo-profiling of both the plant species revealed the presence of some phyto-metabolites with known biocidal properties, more specifically acaricidal properties. Saponin, Flavonoids, Tannins, Phlobatannins and Steroids were analyzed in both the species and revealed that except for Saponin all others metabolites were present in both the species of Datura. Atropine and Scopolamine earlier reported for their acaricidal activity were assayed using HPTLC technique. Shoots of D. stramonium showed the presence of Atropine (0.04238%) and Scopolamine (0.21554%) whereas; the presence of Scopolamine (0.00754%) was detected only in the roots. Presence of Atropine (0.08083%) only was detected in shoots of D. metel. The variation in Atropine as well as Scopolamine in roots and shoots of the same plant species might be due to variance in tissue specific concerned gene(s) expression, and among the different species might be due to genetic variation or variation in eco-geographical conditions which are yet to be explored. Acaricidal properties of both the plant species were assayed in terms of LC50 as well as Inhibition in Oviposition (IO%) against a tick line of Rhipicephalus microplus collected from Assam. Between the two plant species, D. metel showed lower LC50 (6.37%) than D. stramonium (12.27%). In case of IO also, more IO value (76%) was observed in D. metel than D. stramonium (35.27%). The lower LC50 and higher IO values indicate that D. metel has more acaricidal potential than D. stramonium. Findings from the study also showed that shoots of D. stramonium contains both Atropine (0.04238%) and Scopolamine (0.21554%) whereas, D. metel-shoots contain only Atropine (0.08083%) and it is almost double of what D. stramonium contains. The present study indicates that Atropine may be directly associated with acaricidal activity with little or no role of Scopolamine. Although, the study did not involve the analysis of other compounds, their involvement in acaricidal activity cannot be denied. This research can be extended further to explore specific metabolites having acaricidal properties present in other plant systems including Datura for the better and greater interest of development of plant based-based acaricides/insecticides.ThesisItem Open Access STRUCTURAL BREAK ANALYSIS OF RAPESEED AND MUSTARD PRODUCTION IN JORHAT DISTRICT OF ASSAM(AAU, Jorhat, 2020-10) BARUAH, SUJATA; Paswan, R. P.Oilseed crops play a vital role in the Indian agricultural economy and so does in any parts of Assam in terms of area and production. Rapeseed and mustard production in Jorhat have increased from 7817 tonnes in 2012-13 to 9118 tonnes in 2013-14 and then decreased to 8129 tonnes in 2014-15. This reflects the structural change in the economy of the district. The present study is performed to determine the exact time of the structural break in the rapeseed and mustard production, followed by the identification of the factors affecting the crop’s production and finally by examining the presence of cointegration between the crop productivity and the various variables under investigation. The data collected for the study pertained to the annual time series of area, production, productivity, maximum temperature, minimum temperature, total rainfall, bright sunshine hours, and wind speed for the periods 1988-89 to 2014-2015. The results of the structural break analysis reveal that the variables for the crop are non-stationary at levels, indicating the existence of structural breaks. The production of rapeseed and mustard is found to have breaks in the years 1995-96 and 1996-97. Amongst all the factors under investigation, the area is found to have a significant effect on the production of the crop in Jorhat district of Assam. This implies that increasing the land area in the study location may increase the production of the crop in the same place. Johansen’s cointegration test was used to check for the presence of the cointegration between the variables under the crop. It is concluded that the variables in the model are cointegrated. This is followed by the employment of the Vector Equilibrium Correction Model, finally proving the presence of a long-run relationship between the variables. It is found that minimum temperature has a negative relationship with the productivity of the crop whereas area and total rainfall have positive and significant short-run effects on the productivity of rapeseed and mustard crop in the study location.ThesisItem Open Access Molecular characterization of the gut microbes of greater wax moth (Galleria mellonella)(AAU, Jorhat, 2020-01) Saikia, Silpi Shikha; Borah, Basanta KumarGreater wax moth (GWM), Galleria mellonella (Lepidoptera: Pyralidae) is a notorious honey-bee pest found throughout the world. The moth is very destructive to the honeycomb, lays eggs and their larva grows up eating beewax. Beewax is a natural polymer, mainly composed of saturated/ unsaturated, linear/ complex monoesters, hydrocarbons etc. The most frequent hydrocarbon bond in beewax is the CH2-CH2 which is found in polyethylene (PE). Meanwhile, biodegradation of PE by gut microbes of Indian meal moth, Plodia interpunctella and lesser wax moth (a close species of GWM) was reported. As wax-digestion is not a common character of animals, we hypothesized to encounter some microbes in GWM-gut, which could also be responsible for the PE degradation. Therefore, we aimed this investigation to isolate and identify the gut-microbes from GWM following culture-dependant approach. We had characterized several bacterial and fungal species based on culture characteristics, Gram-staining and several biochemical tests such as carbohydrate utilization test, catalase test, citrate utilization test, MR-VP test, motility test etc. Using 16S-rDNA sequencing with conserved primer-sets from representative types, thirteen bacteria and one microalgae were obtained from the digestive tract of G. mellonella. These species includes Gram-positive Exiguobacterium aestuarii, Bacillus circulans, Microbacterium zaea, Microbacterium paraoxydans, Enterococcus faecalis and Gram-negative Agrobacterium sp., Sphingomonas pseudosanguinis, Sphingobium yanoikuyae, Acinetobacter radioresistens, as well as a microalgae (Picochlorum oklahomensis). Several of these species/ isolates have been reported to degrade polycyclic aromatic hydrocarbon, low density polyethylene, 2-methylphenanthrene etc. Interestingly, P. oklahomensis is a marine microalgae; it steals genes from bacteria and adapt themselves to abiotic stress. Further investigation will be required to find out more precise details about plastic degrading candidate microbes and their biotechnological applications.ThesisItem Open Access AN ECONOMIC ANALYSIS OF PRODUCTION AND MARKETING OF ORANGE IN KAMRUP METRO DISTRICT OF ASSAM(AAU, Jorhat, 2020-03) Pator, Sunil; Changmai, H. K.Orange is commercially the most important sub-tropical fruit and one of the most widely cultivated fruit crops. The present study is an attempt to analyse the cost of cultivation of orange farmers, the economics of orange cultivation vis-à-vis competing crop and the marketing channel of orange in Kamrup Metro district of Assam. It will serve as a useful reference guide to the people involved in the cultivation and marketing of this crop as well as a guideline for similar studies that may be undertaken in other parts of the country. The present study is carried out with the following specific objectives: Find out the cost of cultivation of orange in study area; Study the economics of orange cultivation vis-à-vis competing crop; Study marketing of orange in study area. The sampling design consisted of four stages. In the first stage, the Kamrup Metro district of Assam was selected purposively. In the second stage two revenue circles namely Sonapur and Chandrapur were selected purposively. In the third stage, a total of six villages namely Kalangpur N.C, Dondoral N.C, Barkashrong N.C, Chandrapur Bagicha, Niz Panbari, Hingimari Bagicha from the two blocks were selected purposively. In the final stage, 32, 19, 25, 14, 15 and 15 farmers from Kalangpur N.C, Dondoral N.C, Barkashrong N.C, Chandrapur Bagicha, Niz Panbari, Hingimari Bagicha villages were selected randomly to constitute a total sample of 120 farmers. The selected farmers were categorized as small (those having less than 2 ha), medium (those having 2-4 ha) and large (those having more than 4 ha). The findings revealed that the per hectare establishment cost of orange on a small, medium and a large farm in the year 2019 were ₹129357.60, ₹137160.60 and ₹139772.60, respectively. The average maintenance per hectare cost of small farm was estimated to be ₹55265.75, ₹55622.92, ₹57530.97, ₹64107.23 in medium farms ₹64528.75, ₹65050.25, ₹66645.25, ₹66882.75, large farms ₹73058.75, ₹73966.75, ₹75866.95, ₹76987.08 in 10th, 15th, 20th and 22nd year respectively. Benefit-cost ratios were calculated as 1.38, 1.45 and 1.50 for the small, medium and large farms. The average cost per hectare cost for arecanut farm was found to be ₹ 22555.93, ₹ 22297.81, ₹ 22429.49, and ₹ 24992.51 on 8th, 10th, 12th, and 13th year age plants. The net present value and benefit-cost ratio were found to be ₹ 261218.20 and 3.32, respectively. The study of marketing of orange revealed that orange producers sold their products through three marketing channels viz., Channel-I (Producer – Pre-harvest contractor – Retailer – Consumer), Channel-II (Producer- Village Trader – Retailer - Consumer) and Channel-III (Producer- Retailer – Consumer). Among these channels, channel-III was found the most important channel in the study area. The market efficiency was 4.58 in channel-III.ThesisItem Open Access VALIDATION OF DROUGHT RESPONSIVE miRNA IN A DROUGHT TOLERANT RICE CULTIVAR(AAU, Jorhat, 2020-10) Debsarma, Oindrila; Sen, PriyabrataDrought like situation in non-irrigated agriculture system often limits rice production, necessitating introduction of drought tolerance trait into the cultivar of interest. In Assam, effect of dry spells on varieties cultivated on low lands was reported to be reduced up to 43.07%. miRNAs, a class of abundant small noncoding RNAs, have been identified as important regulators of gene expression in both plants and animals and are involved in many aspects of plant development, including the modulation of plant response to stress. Despite technical hurdles to miRNA functional analysis, there is a growing body of evidence that alteration of miRNA accumulation plays an important role in reprogramming plant responses to biotic and abiotic stresses. Assam having a diverse germplasm of rice, might have evolved an unique response to various stress. ARC-10372, a proven drought tolerant landrace may be a good source of drought related miRNAs and can provide insight into the role of miRNA in drought stress. In a previous effort in the Dept. to identify novel variety specific miRNA, small RNA sequencing had been employed to systematically investigate the tissue specific miRNAs responsible to drought stress, which are understudied in rice. The study revealed few novel miRNA in addition to known under drought stress. Differentially expressed miRNA as revealed by sequencing data are confirmed experimentally under drought situation using qRT-PCR. Out of 31 miRNAs, 7 known and 5 novel miRNAs were found to respond to drought stress. The identified target for these miRNAs revealed several conserved miRNAs targeting transcription factors like homeodomain-leucine zipper, MADS box family protein, zinc finger protein and Myb, well known for their importance in drought tolerance in plants. Drastic decrease in abundance of a few of the members of the novel miRNA ( nmiR4, nmiR25, nmiR32, nmiR84 & nmiR86) might suggests important role of these miRNAs in drought tolerance. Further work on revealing its confirmatory role shall yield more information in this regard.ThesisItem Open Access SYMBIOTIC EFFECTIVENESS OF COMMON BEAN (PHASEOLUS VULGARIS L.) RHIZOBIUM GROWN IN SOILS OF ASSAM(AAU, Jorhat, 2020-09) Kalita, Jyotirupa; Nath, Dhruba JyotiNodulation promiscuity and sparse nodulation in common bean (Phaseolus vulgaris L) are two important intrinsic characteristics besides soil chemical factors for low nitrogen (N2) fixation compared to other grain legumes. The symbiotic effectiveness of Rhizobia in nodulation is significant in Rhizobium strain selection programme to avoid the risk of sub optimal nodulation or nodulation failure. The present study was carried out to screen the effective native Rhizobia isolates from field grown common bean for their symbiotic effectiveness. Root nodules and rhizosphere soil were collected from thirteen different common bean growing sites representing three districts viz: Jorhat, Golaghat and Karimganj of Assam for isolation of Rhizobium and to assess their symbiotic effectiveness. Prior to isolation of Rhizobium, the nodulation characteristics of field grown common bean were assessed in correlation with selected soil chemical parameters. The study established the significant variation of nodule number (15.33 -173.67 /plant) and nodule dry weight (8 to 77.67 mg /plant) across the sites and the variation could be attributed to soil organic carbon (r=0.75*, r=0.82*) and available P2O5 in the rhizosphere (r=0.56*, r=0.57*) respectively. The frequencies of purified Rhizobia isolated from the nodules using differential Yeast Extract Mannitol Agar containing congo red (YEMA-CR) media, similarly varied significantly (5.38 to 8.58 log cfug-1) with typical colony characteristics across the sites.Growth in YEM broth exhibited the maximum population ranges (7.29 - 8.60 log cfu mL-1) at 48h, while optical density at 550nm (0.016-0.035) remains maximum at 72h of incubation. Optimum growth was exhibited by the isolates at pH7 and temperature 30o C. Differences in response to intracellular and extracellular enzymes activities, carbon sources utilization, amino acids utilizations, intrinsic antibiotic resistance and release of polysaccharides were observed for isolated Rhizobia. The assesment of changes in shoot root ratio (-54.29 to 180.00), nitrogen content in shoot (4.76-19.01mg plant-1), nodule number (11.40-70.80), nodule dry weight (0.02 to 0.20g), nodule score (3.60-7.00), symbiotic efficiency (213.00-852.00) and relative strain efficiency (3.98-41.3) in ‘Leonard Jar’ assembly exhibited the symbiotic effectiveness of few promising (R01, R06 and 18P) isolated Rhizobium. The linear correlation between shoot dry weight and shoot nitrogen content with nodule dry weight (r=0.65*), further establishes the fully functional N2 fixation system as a result of effective nodulation.ThesisItem Open Access STUDIES ON METABOLISM OF IRON IN RICE(AAU, Jorhat, 2020-10) Baruah, Madhusmita; Das, PriyankaRice, though rich in carbohydrates and proteins, lacks micronutrients like iron and zinc. Considering several disadvantages of fortification of iron in food, emphasis is given on biofortification of iron in plants, including rice grains. Though, there exists threat of iron toxicity in some of the rice varieties grown in lowland acid soils of this region, the present study was conducted to know the effect of two different levels of soil iron content on some biochemical parameters including grain iron content of rice plant. Three rice varieties, including two popular varieties of Assam, Ranjit and Mahsuri, and one traditional pigmented variety Kajoli chakua were cultivated in pots at two different levels of iron: marked as control and treated; in which DTPA extractable iron content of soil were 159.40 mg/kg and 182.35 mg/kg, respectively. Within the range of soil DTPA extractable iron content (159.40 mg/kg - 182.35 mg/kg), iron toxicity was not observed. The analysis revealed that the iron content, chlorophyll content of leaves and the activities of antioxidative enzymes viz. peroxidase, superoxide dismutase and catalase varied significantly at different growth stages. Among the three rice varieties, uptake of iron in rice leaves and grains were found in the order Ranjit > Kajoli chakua > Mahsuri. The iron content of brown rice significantly differed according to its position on the rachis, the order being: top primary rachis > top secondary rachis > middle primary rachis > middle secondary rachis > bottom primary rachis > bottom secondary rachis. The iron content of brown rice of all the three varieties increased significantly (more than 100 % than that of control) in plants grown in soils of higher iron content. Specific activity of all the three enzymes showed that higher the iron content, more the specific activity. Considering initial iron status of the soil, application of iron solution of suitable concentration may be advocated for increasing grain iron content of these three rice varieties.ThesisItem Open Access PROFILE DISTRIBUTION OF POTASSIUM IN SOME SOILS OF SARUPATHAR BLOCK OF GOLAGHAT DISTRICT, ASSAM(AAU, Jorhat, 2020-09) Das, Karabi; Dutta, MaramiThe present investigation was carried out with the objectives to characterize and classify the soils and to study the profile distribution of different forms of potassiumin some soils of Sarupathar Block of Golaghat District, Assam. Horizonwise soil samples from five pedons in different locations viz., P1 (rice), P2 (rice), P3 (rice), P4 (vegetable) and P5 (upland trees) were collected. The soil colour (moist) varied considerably ranging from dark yellowish brown (10YR 4/4) to very pale brown (10YR 7/4) with dominant hue of 10YR in all the pedons. The colour value ranged from 4 to 7 and chroma ranged from 1 to 8. Mottles of higher chroma (6-8) were seen in subsurface horizons of P1, P2 and P3 and dominant hue of the colour of mottles was 7.5YR. A textural variation ranging from loam to silty clay was observed in surface horizons and sandy clay loam to clay was observed in sub-surface horizons. The structure of the soils varied from very fine to medium, weak to strong and sub angular blocky except for the surface horizon of P3 pedon where structure was massive. The sand content in the soils varied from 7.6 to 46.5 per cent, silt varied from 22.3 to 52.8 per cent and clay varied from 16.1 to 49.8 per cent. The value of bulk density for different pedons ranged from 1.35 to 1.50 Mg m-3. Organic carbon tended to decrease with depth in all pedons except for P4. The pH values were in acidic range in all the pedons and the pH values were lower in the surface horizons as compared to the subsurface horizons.Ca2+ was found to be the dominant cation followed by Mg2+, Na+ and K+ in all the pedons except in P5, where the sequence was Mg2+>Ca2+>Na+>K+. CEC of the soils ranged from 7.5 to 14.2 cmol (p+) kg-1 soil and per cent base saturation (PBS) ranged from 14.27 to 47.02. Available N and available P2O5 ranged from 65.80(L) to 487.60(M) and 8.21(L) to 28.78(M) kg ha-1, respectively. The studied soils were classified as Aquic Dystrudepts (P1), Oxyaquic Dystrudepts (P2), Typic Endoaquepts (P3), Typic Udifluvents (P4) and Typic Dystrudepts (P5) at subgroup level. Water soluble K status of the soils was found in the range of 0.85- 8.45 mg kg-1. Exchangeable K status of the soil samples was found to be in the range of 10.65 - 92.45 mg kg-1. Available K status of the soil samples was recorded in the range of 15.55 - 100.90 mg kg-1 in the studied pedons and contribution to total K was 0.15- 0.76 per cent. Status of non-exchangeable K was found in the range of 172.70 - 296.60 mg kg-1 which contributed 0.93-3.93 per cent of total K. No specific trend was seen in any of the profile in case of non-exchangeable K content. Lattice K status was found in 7 the range of 4365.30 – 19966.85 mg kg-1. The mineral pool of K is the main source of total K which accounts more than 90 per cent of the total K. The value of total K in the studied soils was found in the range of 4580 – 20200 mg kg-1. The results indicated that the pH of the soil samples showed significant positive relationship with nonexchangeable K (r = 610**). The organic carbon content of the studied soils showed positive and significant correlation with water soluble K (r = 416*). The cation exchange capacity of the soils showed a significant positive relationship with exchangeable, available, lattice and total forms of potassium. Highly significant and negative correlations were observed between exchangeable, available, lattice and total forms of potassium with total sand content of the soils. Clay showed significant positive relationship with exchangeable, available, lattice and total forms of potassium. Available K showed a significant and positive correlation with exchangeable K (r =0.994**), lattice K (r = 0.517**) and total K (r = 0.520**). The correlation coefficient between forms of potassium indicated that exchangeable K had significant positive correlation with lattice K (r = 0.569**) and total K (r = 0.571**).A highly significant and positive correlation was also found between lattice K and total K (r = 0.999**) in the studied soils of Sarupathar block of Golaghat district.
