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Assam Agricultural University, Jorhat
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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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ThesisItem Open Access ORGANIC AMENDMENTS AND MULCHING FOR GROWTH, FLOWERING, YIELD, SEED PRODUCTION AND POST HARVEST LIFE IN CHINA ASTER(2022) Konwar, Binita; Talukdar, Madhumita ChoudharyThe investigation was conducted at Dhemaji during 2019-20 and 2020- 21, to study the effect of Organic amendments and mulching for growth, flowering, yield, seed production and post harvest life in China aster consisting of 36 treatments and 3 replications. Post-harvest quality of flowers was further studied for long distance transport in four different packaging material and three harvesting stages. The vegetative characters in pooled data were highly influenced by the nutrient treatment N4 (Microbial consortium (Bio fertilizers) + Rock Phosphate @ 5 g/m2 + Vermicompost @ 3.0 t/ha) where the highest plant height 60.00 cm , 205.68 number of leaves, 8.25 number of branches and 3313.39 cm2 leaf area. Similarly the mulching M2 (Silver lined plastic mulching) and its interaction with N4 i.e., N4M2 recorded the highest values for these traits. The minimum days for full bloom was recorded in the nutrient treatment N4 with 107.65 days, the mulching treatment M2 with 112.16 days and their interaction (N4M2) with 104.36 days. The nutrient treatment N4 recorded the highest number of flowers of 52.58, blooming period of 45.31 days, self life of 13.77 days and vase life of 11.15 days. The red plastic mulching (M3) was found to record higher values in terms of flower characters though at par with M2. The interaction treatment N4M2 recorded the highest number of flowers per plant (54.23) while N4M3 recorded at par performance with N4M2 showing maximum blooming period of 48.87 days, self life of 14.08 days and vase life of 11.73 days in pooled data. The physiological parameters were highly influenced by the nutrient treatments with N4 recording the highest chlorophyll content of 3.24 mg g-1, anthocyanin content of 309.02 mg 100g-1, NAR of 0.92 and RLWC of 93.21%. The mulching treatment M3 recorded highest values in terms of the above physiological parameters. The highest seed yield was observed in the treatment N4 (8.10 g/plant and 13.49 q/ha), M2 (7.52 g/plant and 12.53 q/ha) and the interaction N4M2 (8.45 g/plant and 14.09 q/ha). The germination percentage and seedling vigour showed a decreasing trend with increase in time from harvest when stored in room temperature. 6 The soil characters in the pooled analysis were found to be highest in terms of Organic carbon, pH, enzymes and microbial biomass carbon with the application of Enriched compost @3.0 t/ha (N8). In the post harvest study after transportation, packaging with high density polyethylene and flowers harvested at the full bloom stage recorded the lowest PLW (45.00%), wilting (71.85%), rotting (22.29%) and highest vase life (7.39 days) on the 5th day in the pooled data. The B:C ratio was found highest in the treatment N4M2 (4.57 and 5.54) followed by N4M3 (4.05 and 5.09) and N8M2(3.74 and 4.74) for flower and seed characters, respectively.ThesisItem Open Access Canopy and Micronutrient Management of Thailand ber (Ziziphus mauritiana Lamk.)(2022) Sarma, Bhaskarjyoti; Kotoky, UtpalThe present experiment on “Canopy and micronutrient management of Thailand ber (Ziziphus mauritiana Lamk.)” was carried out for two successive years during 2020- 21 and 2021-22 in the farmer‟s field at Pundibari village, Dompara, Bongaigaon with the objective to standardize the pruning height and to find out optimum doses of boron and zinc. The experiment was laid out in factorial Randomized Block Design with 3 factors viz. variety, pruning height and micronutrient sprays with three replications and the data of individual years were subjected to pooled analysis. The varieties V1 (Round green type) and V2 (Roundish ovate reddish type) were pruned at height P1 (50 cm from ground level) and P2 (75 cm from ground level). A total of nine micronutrients treatment were given i.e. N0 (control), N1 (Borax 0.4%), N2 (Borax 0.5%), N3 (ZnSO4 0.4%), N4 (ZnSO4 0.5%), N5 (Borax 0.4% + ZnSO4 0.4%), N6 (Borax 0.4% + ZnSO4 0.5%), N7 (Borax 0.5% + ZnSO4 0.4%) and N8 (Borax 0.5% + ZnSO4 0.5%). The plant height was not influenced by any of the treatments. The variety V1 (Round green type) recorded the earliest flowering (121.25 days), heavier fruits (35.49 g) leading to higher yield per plant (31.17 kg) although the variety V2 (Roundish ovate reddish type) exhibited better fruit quality, viz., the highest TSS (15.00 oBrix), total sugar (15.14%), reducing sugar (8.08%), carotenoid (0.33 μg/g), vitamin C content (68.49 mg/100 g) and DPPH scavenging ability (9.96%). Pruning at 75 cm above ground level (P2) resulted in more number of primary branches (8.28) leading to more fruits (148.90/branch) and better quality fruits in terms of size, TSS, total sugar, reducing sugar, carotenoid content and the lowest titratable acidity. Among the micronutrient sprays, borax 0.5 per cent along with zinc sulphate 0.5 per cent (N8) was most effective with respect to fruit retention (56.65%), more fruits per branch (146.90) and better quality fruits. The N8 treatment favourably influenced the TSS, total and reducing sugars, titratable acidity and total leaf chlorophyll content. The interaction of three factors revealed that V1P2N3 was better for number of primary branches, while V2P1N4 recorded the highest DPPH scavenging ability (10.05%). Although V2P2N8 (Roundish ovate reddish type variety, pruning at 75 cm from ground level, Borax 0.5% + ZnSO4 0.5% spray) registered the maximum number of fruits (181.24/branch), the highest fruit yield (85.18 t/ha) was obtained in the treatment V1P2N8 (Round green type variety, pruning at 75 cm from ground level, Borax 0.5% + ZnSO4 0.5% spray) owing to differences in fruit size. The treatment combination V2P2N8 was registered to be better in vitamin C content (70.28 mg/100 g) and other quality parameters along with total leaf chlorophyll content (4.32 mg/g FW). Computation of production economics revealed the B:C ratio to be the highest in V2P2N8 (7.36), followed by V2P2N7 (7.08).ThesisItem Open Access A STUDY ON FARMERS’ PERSPECTIVE TOWARDS AGRICULTURE IN THE LAST FIVE DECADES IN THE STATE OF ASSAM(2021) Baruah, Bhargab; Kalita, Hemanga Kr.A lack of approach towards agricultural activities can be observed in the rural areas of Assam despite having economic crisis at the household level. While the notion of disenchantment of farmers towards the profession and the likelihood of many farmers willing to leave agriculture has caught steam in the country, considering how important agriculture is to the lives and livelihood of rural population in Assam the present study was taken up to develop insights into the reasons behind decline in preference of the farmers in Assam to continue performing agriculture as their primary livelihood activity. This study proposes that farmers’ psychologically constituted attitude, values and goals towards life domains shall help us understand the foundational basis of preferences and choices of farmers to engage in agriculture as a profession and for fulfillment lifestyle goals under changed circumstances to perform agriculture as a livelihood. The present study was conducted in five districts across Assam, viz., Jorhat, Morigaon, Barpeta, North Lakhimpur, and Cachar. Data was mainly collected through personal interview channels, and employing psychometric assessment techniques - Likert-scale and Q-methodology. Multi-stage purposive and random sampling techniques was used to draw out a sample of 400 respondents proportionately from three stratums based on age categories. A purposively drawn sub-sample of respondents was used for Q-study. Cluster analysis and factor analysis were used for interpretation of the data. Other appropriate analytical tools were also used for analysis of data. The study revealed that although food production was simply seen as a means to meet a minimum level of subsistence through collective action of family members during phase 1, the farmers did not face economic crisis at household level. Farming was more about maintenance of traditional rural/agricultural values, than economic rationality and modern technological innovations had very little importance in farming. Farming was mainly constrained by damage due to floods, lack of policies to safeguard farm household economy against crop loss and access to for credit channels. While there was shift in preferences among expanders, contended believers and potential escapees during phase 2 to utilize their farm holdings for earning a real income from farming most others preferred to farm at subsistence level. Family remained central to the management of farms and farmers drew comfort from being part of his private social world, while many started to see farmers being viewed as inferior section of the society. Farmers became aware that the resources that were accessible and affordable to them would not be enough for a settled life in farming. Farmers were unhappy with the prices of farm produce and the smaller farmers felt that they were relegated to poorer section of the society. Although there was increase in use of modern technologies in farming, the quality planting materials were costly and the situation in marketing did not allow farmers to get a remunerative price. Access to irrigation and credit was also limited. Role of extension was passive and improvements in mechanization was not achieved. Damage to crops due to floods remained a primary concern for the farmers. Economic rationality in food production took over the idealistic values of being a farmer embedded in the traditionalist rural/agricultural culture during phase 3. Leaving aside the potential escapees, it appeared that the others view their farm household enterprise to be of considerable importance for their livelihood, although their livelihood strategies differed. For the expanders maintenance of traditional and cultural values in farming and opportunity of self-expression in farming occupation was as important as economic rationality in farming. They enjoyed better wellbeing and status and saw prospects of expansion of their farm business. Otherwise oriented towards commercial cultivation, some of the contended believers have been quite selective in making changes to their farming systems during phase 3. Although some contended conservators prefer to be commercially oriented, for most of them food production at subsistence or semi-subsistence level seems quite the preferable choice. Being oriented towards farming at subsistence level, the continuing bottomliners believed that farming must be carried out with collective action of family members. The symbolic status of owning agricultural land and performance of work tasks, preserving their lands for the future generation and working hard in the land to grow a good crop no longer ensures economic rewards in farming. Change in the institutional life-world within which the farmers are embedded, threatened the traditional values in farming and forced the farmers to question their self-worth. Unsatisfactory performance of extension service, credit and insurance, non-existence of storage facilities, intuitional support in marketing constrained progress of farmers. Irrigation and mechanization improved, while modern quality inputs were easily available. The growth in non-farm employment, within and outside rural areas, made family farming more attractive. While only 8.95 per cent farm households reported to have off-farm source of livelihood during phase 1, 72.50 per cent of households indicated that they had off-farm sources of income during phase 3. While potential escapees had at least one off-farm source of income during phase 3, the contended believers less frequently had an off-farm source of income in their household (56.25%). While 93.68 per cent farmers reported that they were highly dependent on agriculture for livelihood during phase 1, only 49.75 per cent reported that their dependence on agriculture was high during phase 3. While majority of potential escapees (69.64%) reported to have very low dependence on agriculture; majority of expanders (67.05%) and contended believers (65.18%) reported that they were highly dependent on agriculture during phase 3. Although there are fewer households in phase 3 that get their principal income from cultivation than in phase 1 and phase 2, majority of farmers (68.75%) still get their principal income from cultivation. Other off-farm enterprises (10.25%) was the most utilized form of employment for principal income by the farmers during phase 3 next to cultivation, followed by salaried employment (9.50%), and other wage employment (7.5%). Other off-farm enterprises (37.50%), salaried income (25%), and other wage employment (21.42%) were the most prominent principal sources of income for the potential escapees. Only as few as 5.50 per cent of the farmers reported that they were dependent on single source of income for livelihood during phase 3. As many as 38.50 per cent of farmers reported that they depended on three sources of income, while another 16.50 per cent farmers depended on four or more sources of income during phase 3. Other sources category of income was frequently utilized by the expanders, potential escapees and contended believers. Salaried income was an important source of income for potential escapees, expanders and contended believers. The contended conservators can be frequently found to be either a wage labour in nonfarm or operating a petty business while the continuing bottomliners are more likely to be involved in wage labour - nonfarm or in blue collar jobs.ThesisItem Open Access Optimization of in vitro transformation protocol and RNAi based gene silencing for viral (Cucumber Mosaic Virus) resistance in Bhut jolokia (Capsicum chinense Jacq.)(2021) Deuri, Bharati; Bhorali, PriyadarshiniBhut jolokia (Capsicum chinense Jacq.), one of the most popular and hottest chillies in the world, is widely cultivated in Assam and other North Eastern regions in India. A member of the Solanaceae family, Bhut jolokia is characterized by very high pungency due to the presence of high amount of phenolic alkaloid ‘Capsaicinoids’. It is an ideal chilli variety for extraction of oleoresin and capsaicin, which have high market demand due to their industrial uses and medicinal properties. Bhut jolokia production is challenged by several biotic constraints, particularly viral diseases, which affect its quality and yield. Among the viruses, Cucumber Mosaic Virus (CMV) causes severe crop damage, leading to low productivity. Current control measures for CMV are mainly preventive through vector management strategies, which are not adequate in controlling the disease. An effective way to control the disease is the use of biotechnological tools such as RNA interference (RNAi) technology to engineer resistance against the virus. Plants expressing a copy of a viral gene in sense and/or antisense orientation have shown resistance upon infection with the virus via post-transcriptional gene silencing. In the present investigation, an in vitro regenerationtransformation strategy has been optimized for Bhut jolokia and, a hairpin RNA (hpRNA) based gene silencing construct has been developed using the Replicase gene from CMV. The study was initiated by callus induction from Bhut jolokia leaf segments in MS basal medium. Very good quality callus were induced in MS medium supplemented with 0.5 mg/l or 1 mg/l 2,4-D. Multiple shoot induction and regeneration from callus were obtained in MS medium supplemented with 8.5 mg/l KIN and 0.5 mg/l TDZ along with 5 mg/l AgNO3 with maximum shoot initiation frequency of 95% and regeneration frequency of 90%. Root regeneration was found to be optimum in half strength MS medium supplemented with 1.5 mg/l NAA within 4 weeks of culture with maximum rooting frequency of 70%. For standardization of an Agrobacterium-mediated genetic transformation system, the strain LBA4404 carrying pCAMBIA1301 binary vector construct with gusA as the reporter gene and hptII and nptII as selection marker genes was used. Transformation was carried out using 45 days old callus and also with intact Bhut jolokia seeds as explants. Hygromycin concentration of 9 mg/l was found to be optimum for efficient selection of putative transformants. From a total of 30 nos. of callus infected by Agrobacterium, 9 numbers of putative transformed shoots were regenerated in presence of selection agent. Finally, only 2 (6.66%) fully rooted plants survived out of which, only 1 plant finally survived during hardening in the green house. Moreover, out of 30 nos. of infected seeds, a total of 7 numbers of putative transformed seedlings were developed. Finally, only 1 (3.33%) seedling survived, which was transferred to the green house for hardening. Thus, both callus and seeds could be used as explants for transformation in Bhut jolokia, although the frequency of putative transformants obtained using callus explants was higher than that in seed transformation. The putative transformants were confirmed by GUS histochemical assay and PCR analysis. For developing the RNAi construct, a 323 bp Replicase gene sequence was cloned into pHANNIBAL vector both in sense and anti-sense orientations. The construct was then transferred to pBI121 binary vector, which was electroporated into Agrobacterium strain LBA4404 for plant transformation. Functional validation of the CMV Replicase hp-RNA construct was done through bioassay in model plant Nicotiana benthamiana by Agro-infiltration. Transgene expression in N. benthamiana was confirmed by RT-PCR analysis. The bioassay results indicated suppression of CMV infection in Agro-infiltrated N. benthamiana plants when mechanically inoculated with CMV sap. Further, DAS-ELISA established the functional efficiency of the hpRNA construct in providing considerable level of resistance against CMV infection. The in vitro regeneration-transformation strategy and the hpRNA based gene silencing construct, developed through this study would serve as a foundation towards future studies on engineering resistance against CMV in Bhut jolokia.ThesisItem Open Access INTEGRATED NUTRIENT MANAGEMENT IN YELLOW SARSON - GREENGRAM CROPPING SYSTEM UNDER RAINFED CONDITION(2016) Gogoi, Bebi; Ojha, N. J.A field experiment entitled “Integrated nutrient management in yellow sarson - greengram cropping system under rainfed condition” was carried out at the Instructional-cum-Research farm of Assam Agricultural University, Jorhat during two consecutive rabi (Oct-Feb) followed by summer (Feb-May) seasons of the year 2017- 2018 and 2018-2019. The experiment was laid out in randomized block design for first crop and split plot design for second crop with three replications. The eight INM practices viz., 100% RDF (60-30-30 kg/ha N-P2O5-K2O) (Y1), 100% RDF + biofertilizer consortium (Y2), 75% RDF + 25% N through vermicompost (Y3), 75% RDF + 25% N through vermicompost + biofertilizer consortium (Y4), 50% RDF + 50% N through vermicompost (Y5), 50% RDF + 50% N through vermicompost + biofertilizer consortium (Y6), 25% RDF + 75% N through vermicompost (Y7) and 25% RDF + 75% N through vermicompost + biofertilizer consortium (Y8) were applied to yellow sarson crop. In greengram crop the residual effect of the treatments applied to yellow sarson were allotted in main plots and two different integrated nutrient management practices viz., 100% RDF + biofertilizer consortium (G1) and 50% RDF + biofertilizer consortium (G2) in the sub plots. The soil of the experimental site was sandy loam in texture, acidic in reaction (pH 5.40 and 5.56), medium in organic carbon (0.69 and 0.72%), available N (274.86 and 290.75 kg/ha), available K2O (138.16 and 140.89 kg/ha) and low in available P2O5 (17.90 and 20.30 kg/ha) in the year 2017-18 and 2018-19, respectively. Experimental findings revealed that application of 75% RDF + 25% N through vermicompost + biofertilizer consortium (Y4) resulted in significantly higher growth as well as yield attributing characters like plant height, number of branches per plant, dry matter accumulation, crop growth rate, relative growth rate, number of siliquae per plant, length of siliqua, number of seeds per siliqua in both the years. The highest seed yield of 998.34, 1026.22 and 1012.28 kg/ha, stover yield of 2393.97, 2420.65 and 2407.31 kg/ha during 2017-18, 2018-19 and in pooled analysis, respectively, were recorded with treatment having 75% RDF + 25% N through vermicompost + biofertilizer consortium (Y4). The seed oil content of 36.40 and 36.97% and seed protein content of 13.27 and 13.44% were also recorded in Y4 in 1st and 2nd year, respectively. Similar effects of this treatment were also observed in respect of N, P and K content and uptake by both seed and stover. However, soil microbial population, microbial biomass carbon, phosphomonoesterase activity and fluorescein di-acetate hydrolase activity after harvest of yellow sarson were significantly higher in treatment having 25% RDF + 75% N through vermicompost + biofertilizer consortium (Y8). The crop recorded the highest gross return (` 56105 in 2017-18 and ` 57652 in 2018-19), net return (` 35407 during 2017-18 and ` 36954 during 2018-19) and benefit-cost ratio (2.71 during 2017-18 and 2.79 during 2018-19) with the treatment containing 75% RDF + 25% N through vermicompost + biofertilizer consortium (Y4). 7 In case of greengram, residual effect of 25% RDF + 75% N through vermicompost + biofertilizer consortium (Y8) resulted in significantly higher growth as well as yield attributing characters like plant height, number of branches per plant, dry matter accumulation, crop growth rate, number of pods per plant and number of seeds per pod in both the years. The effect of these was reflected in higher seed yield (849.56, 806.56 and 828.06 kg/ha in the year 2018, 2019 and in pooled analysis, respectively) and stover yield (2012.68, 1935.58 and 1974.13 kg/ha in 2018, 2019 and in pooled analysis, respectively) under the same integrated nutrient management practices. The maximum values of N, P and K uptake by seed and stover, soil microbial population, microbial biomass carbon, phosphomonoesterase activity and fluorescein di-acetate hydrolase activity after harvest of greengram were also observed under this treatment (Y8). However,direct application of 100% RDF + biofertilizer consortium (G1) brought about higher values in growth parameters, yield attributes, yield of seed (804.21, 724.68 and 764.45 kg/ha during 2018, 2019 and in pooled analysis, respectively) and stover yield (1830.89, 1763.80 and 1797.35 kg/ha during 2018, 2019 and in pooled analysis, respectively), protein content in seed (22.39 and 22.26% in 2018 and 2019 respectively), content and uptake of N, P and K by both seed and stover, soil microbial population, microbial biomass carbon, phosphomonoesterase activity and fluorescein diacetate hydrolase activity after harvest of greengram over 50% RDF + biofertilizer consortium (G2). The highest gross return (` 50726 in 2018 and ` 48922 in 2019), net return (` 33611 during 2018 and ` 31807 during 2019) and benefit-cost ratio (2.96 during 2018 and 2.86 during 2019) were observed under treatment Y8G1 containing 100% RDF + biofertilizer consortium (G1) + residue of treatment Y8 (25% RDF + 75% N through vermicompost + biofertilizer consortium). In regards to yellow sarson-greengram cropping system the highest yellow sarson equivalent yield (1678.57 and 1614.02 kg/ha in 2018 and 2019, respectively) were obtained by treatment Y4G1 containing 100% RDF + biofertilizer consortium (G1) + residue of treatment Y4 (75% RDF + 25% N through vermicompost + biofertilizer consortium). The highest gross return (` 93518 in 2017-18 and ` 89981 in 2018-19), net return (` 55705 during 2017-18 and ` 52168 during 2018-19) and benefit-cost ratio (2.47 during 2017-18 and 2.37 during 2018-19) of yellow sarsongreengram cropping system were observed under treatment Y4G1, containing 100% RDF + biofertilizer consortium (G1) + residue of treatment Y4 (75% RDF + 25% N through vermicompost + biofertilizer consortium). The performance of yellow sarsongreengram cropping system was assessed on the basis of yellow sarson equivalent yield, net monetary returns and B-C ratio. The application of 75% RDF + 25% N through vermicompost + biofertilizer consortium to yellow sarson and 100% RDF + biofertilizer consortium to greengram was the most beneficial combination compared to rest of the treatments.ThesisItem Open Access POPULATION DYNAMICS AND CROP LOSS ASSESSMENT OF MAJOR INSECT PESTS OF CUCUMBER (Cucumis sativus)(2022) Ganesh, Balaga Mohan; Saikia, D.K.Cucumber (Cucumis sativus L.2n = 14) is one of the widely cultivated summer vegetable crops from the gourd family of Cucurbitaceae which is native to India. The climatic conditions of northeast India especially Assam are highly conducive for reproduction of insects, and this region has been considered to be a biodiversity hotspot. Moreover, this region has huge potential for the production of vegetable crops especially cucurbits, but insect pests like fruit flies, pumpkin beetle and sucking pests are major limiting factors for successful cultivation of cucurbits like cucumber etc. Therefore, understanding population fluctuation in the field in relation to losses caused by insect pests are a function of their population dynamics which needs to be thoroughly studied. In view of above factors, an investigation on “Population Dynamics and Crop Loss Assessment of Major Insect Pests of Cucumber (Cucumis sativus)” was carried out at Horticultural Farm and RNA laboratory of Agricultural Biotechnology, Assam Agricultural University, Jorhat. The results showed that during 2019 -2021 summer season, the red pumpkin beetle first appeared on 24th April 2019 and 7th May 2020 with initial population of 4.51 and 2.23 beetles per plant, respectively. However, maximum beetle populations were recorded on 8thMay 2019 and 3rd July 2020 with 6.15 and 6.52 beetles per plant, respectively. Similarly, during 2019-2021, the fruit infestation by fruit fly was recorded first time on 13th June, 2019 and 26th June ,2020 with per cent fruit infestation of 10.24 per cent and 10.75 per cent, respectively. However, highest level of fruit infestation by fruit fly was observed on 25th July, 2019 and 8th August 2020 with 46.86 and 41.3 per cent fruit infestation, respectively. The data on relative abundance of different insects of cucumber during 2019-2021 revealed that the relative abundance of fruit fly species, Bactrocera dorsalis (62.27%) was the highest followed by B. tau (15.68%), B. cucurbitae (10.73%), Dacus longicornis (2.47%), Coccinella transversalis (2.45%), Aulacophora foveicollis (2.20%), Micrapsis discolor (1.56%), A. frontalis (1.16%), and Coccinella septumapunctata (1.08%). During 2019 and 2020, the Simpson-Index diversity showed highest value for fruit fly (0.97 and 0.94) followed by predacious coccinellid beetles (0.67 and 0.71) and red pumpkin beetle (0.55 and 0.64), respectively. Whereas, Shannon-Wiener index diversity (H’) during 2019 and 2020 observed highest in fruit fly (1.65 and 1.85) followed by predacious coccinellid beetles (1.15 and 1.05) and pumpkin beetle (0.68 and 0.85), respectively. The results of yield loss studies during 2019-2020 revealed that the per cent fruit infestation was highest in untreated control plot (30.73%) compared to treated plot (26.8%) with fruit yield of 1223.91 kg/ha and 2311.83 kg/ha, respectively. The yield loss in untreated plot was recorded as 1087.91 kg/ha with 47.05 per cent avoidable loss in yield. Whereas, per cent yield increase over control during 2019-2021 (summer season) was observed as 88.88 per cent. However, economic injury level (EIL) of fruit fly with respect to cucumber was determined as 15.27 and 10.40 per cent with per cent fruit loss of 0.743 and 0.745 during 2019 and 2020, respectively. The optimal phylogenetic tree of 10 fruit fly specimens collected from different locations grouped into two clusters (Cluster A and Cluster B) of two specimens out groups namely B. rubigina and D. longicornis with branch length of 0.0724. In cluster-A, highest genetic distance of 0.047 was recorded between B. rubigina and B. dorsalis. Similarly, in cluster-B the highest genetic distance of 0.0682 was recorded between D. longicornis, B.tau and B.cucurbitae collected from different locations.ThesisItem Open Access POPULATION DYNAMICS AND CROP LOSS ASSESSMENT OF MAJOR INSECT PESTS OF CUCUMBER (Cucumis sativus)(2022) Balaga Mohan Ganesh; Saikia, D.K.Cucumber (Cucumis sativus L.2n = 14) is one of the widely cultivated summer vegetable crops from the gourd family of Cucurbitaceae which is native to India. The climatic conditions of northeast India especially Assam are highly conducive for reproduction of insects, and this region has been considered to be a biodiversity hotspot. Moreover, this region has huge potential for the production of vegetable crops especially cucurbits, but insect pests like fruit flies, pumpkin beetle and sucking pests are major limiting factors for successful cultivation of cucurbits like cucumber etc. Therefore, understanding population fluctuation in the field in relation to losses caused by insect pests are a function of their population dynamics which needs to be thoroughly studied. In view of above factors, an investigation on “Population Dynamics and Crop Loss Assessment of Major Insect Pests of Cucumber (Cucumis sativus)” was carried out at Horticultural Farm and RNA laboratory of Agricultural Biotechnology, Assam Agricultural University, Jorhat. The results showed that during 2019 -2021 summer season, the red pumpkin beetle first appeared on 24th April 2019 and 7th May 2020 with initial population of 4.51 and 2.23 beetles per plant, respectively. However, maximum beetle populations were recorded on 8thMay 2019 and 3rd July 2020 with 6.15 and 6.52 beetles per plant, respectively. Similarly, during 2019-2021, the fruit infestation by fruit fly was recorded first time on 13th June, 2019 and 26th June ,2020 with per cent fruit infestation of 10.24 per cent and 10.75 per cent, respectively. However, highest level of fruit infestation by fruit fly was observed on 25th July, 2019 and 8th August 2020 with 46.86 and 41.3 per cent fruit infestation, respectively. The data on relative abundance of different insects of cucumber during 2019-2021 revealed that the relative abundance of fruit fly species, Bactrocera dorsalis (62.27%) was the highest followed by B. tau (15.68%), B. cucurbitae (10.73%), Dacus longicornis (2.47%), Coccinella transversalis (2.45%), Aulacophora foveicollis (2.20%), Micrapsis discolor (1.56%), A. frontalis (1.16%), and Coccinella septumapunctata (1.08%). During 2019 and 2020, the Simpson-Index diversity showed highest value for fruit fly (0.97 and 0.94) followed by predacious coccinellid beetles (0.67 and 0.71) and red pumpkin beetle (0.55 and 0.64), respectively. Whereas, Shannon-Wiener index diversity (H’) during 2019 and 2020 observed highest in fruit fly (1.65 and 1.85) followed by predacious coccinellid beetles (1.15 and 1.05) and pumpkin beetle (0.68 and 0.85), respectively. The results of yield loss studies during 2019-2020 revealed that the per cent fruit infestation was highest in untreated control plot (30.73%) compared to treated plot (26.8%) with fruit yield of 1223.91 kg/ha and 2311.83 kg/ha, respectively. The yield loss in untreated plot was recorded as 1087.91 kg/ha with 47.05 per cent avoidable loss in yield. Whereas, per cent yield increase over control during 2019-2021 (summer season) was observed as 88.88 per cent. However, economic injury level (EIL) of fruit fly with respect to cucumber was determined as 15.27 and 10.40 per cent with per cent fruit loss of 0.743 and 0.745 during 2019 and 2020, respectively. The optimal phylogenetic tree of 10 fruit fly specimens collected from different locations grouped into two clusters (Cluster A and Cluster B) of two specimens out groups namely B. rubigina and D. longicornis with branch length of 0.0724. In cluster-A, highest genetic distance of 0.047 was recorded between B. rubigina and B. dorsalis. Similarly, in cluster-B the highest genetic distance of 0.0682 was recorded between D. longicornis, B.tau and B.cucurbitae collected from different locations.ThesisItem Open Access MANAGEMENT OF POTASSIUM IN ORGANIC BLACK RICE UNDER SYSTEM OF RICE INTENSIFICATION(2021) Dambale, Ashok Sambhaji; Goswami, J.A field experiment entitled “Management of potassium in organic black rice under system of rice intensification” was conducted at the organic block, Instructionalcum- Research Farm of Assam Agricultural University, Jorhat during kharif seasons, 2019 and 2020 to evaluate the effect of different organic inputs on growth, yield, quality and economics of organic black rice along with cumulative effects on soil health under the system of rice intensification (SRI).The experiment consisted of twelve different treatments viz.,Control (T1), Potash solubilizing bacteria (KSB) @ 3.5 kg ha-1 as root dip treatment (T2), RDK through azolla incorporation (T3), RDK through water hyacinth incorporation (T4), RDK through banana pseudo stem vermicompost (T5), RDK through azolla incorporation + mustard oil cake @ 20 kg ha-1 (T6), RDK through water hyacinth incorporation + mustard oil cake @ 20 kg ha-1 (T7), RDK through banana pseudo stem vermicompost + mustard oil cake @ 20 kg ha-1 (T8), RDK through azolla incorporation + Potash solubilizing bacteria (KSB) @ 3.5 kg ha-1 as rood dip treatment (T9), RDK through water hyacinth incorporation + Potash solubilizing bacteria (KSB) @ 3.5 kg ha-1 (T10), RDK through banana pseudo stem vermicompost + Potash solubilizing bacteria (KSB) @ 3.5 kg ha-1(T11), Indigenous traditional knowledge (T12). The experiment was laid out in a Randomized Block Design (RBD) with three replications. The soil of the experimental site was sandy loam in texture with pH 5.28, organic carbon (0.72 %), CEC {6.58c mole (p+)/ kg}, low in available nitrogen (246.45 kg ha-1) and available P2O 5 (21.02 kg ha-1) but medium in available K2O (144.80 kg ha-1). The total rainfall received during the crop season was 928.2 mm with 43 rainy days in 2019 and 1272.10 mm with 69 rainy days in 2020. The mean maximum and minimum temperature during the whole crop growing period ranged from 30.6 to 21.3°C during 2019 and 32.09 to 24.28 °C during 2020, respectively. The growth, yield attributes and yield of organic black rice was significantly influenced by different K management practices. Among the different growth parameters viz., leaf area index, no. of leaves, root dry weight, shoot dry weight, root: shoot ratio, root length, root volume, no. of tillers and dry matter accumulation except plant height at different stages were observed to be significantly higher with the application of RDK through banana pseudo stem vermicompost + mustard oil cake @ 20 kg ha-1 i.e. treatment T8, while the lowest values were recorded under the control treatment T1.In case of yield and yield attributing characters like, no. of panicles m-2 , panicle length, panicle weight, no. of filled and unfilled grains and test weight were found to be superior in respect of almost all the studied parameters under the treatment T8. The highest no. of panicles (m-2) 294.10, 305.20, panicle length 27.49 (cm), 28.87 (cm), panicle weight 4.87 (g), 4.89 (g), no. of filled grains panicle-1 pooled 214.53, no. of unfilled grains panicle-1 pooled 26.73 and test weight 24.48 (g) 24.56 (g), respectively during 2019 and 2020 were also found highest with treatment T8. The highest pooled grain (24.52 q ha-1), straw (46.07 q ha-1) and biological yield (70.59 q ha-1) were registered with the treatment T8 i.e. RDK through banana pseudo stem vermicompost + mustard oil cake @ 20 kg ha-1. The quality parameters of black rice were also significantly influenced by different K management practices. The quality parameter includes length and breadth of kernel, L/B ratio, protein content and milling qualities. The maximum quality parameters were found highest under treatment T8 (RDK through banana pseudo stem vermicompost along with 20 kg of mustard oil cake) followed by T6 (RDK through azolla incorporation along with mustard oil cake @ 20 kg ha-1) except protein content where as highest protein content (7.96 during 2019 and 7.98 % during 2020) was found under treatment T6 (RDK through azolla incorporation + mustard oil cake @ 20 kg ha-1) followed by T9 (RDK through azolla incorporation along with Potash solubilizing bacteria @ 3.5 kg ha-1). The N, P and K contents and total uptake by grain and straw were significantly influenced by different K management practices. The highest uptake of N (65.74 kg ha1) was found in T6, P (11.4 kg ha-1) and K (39.56 kg ha-1) were found in T8 respectively. The influence of different organic inputs on available N, P2O5 and K2O in soil after harvesting was found significant. The highest pooled value of available N was recorded with T6 treatment i.e. RDK through azolla incorporation + mustard oil cake @ 20 kg ha-1and in case of P2O5 and K2O the highest pooled values recorded under T8 treatment i.e. 43.07 kg ha-1, 159.86 kg ha-1 respectively. The soil biological properties and enzymatic activities of black rice cultivated soil were significantly influenced by different organic inputs. The higher values of soil microbial biomass carbon (642.77 μg/g dry soil during 2019 and 687.44 μg/g dry soil during 2020, Bacteria population (7.12 log cfu/g soil during 2019 and 7.18log cfu/g soil during 2020, fungal population (4.86 log cfu/g soil during 2019 and 4.89 log cfu/g soil during 2020 , dehydrogenase activity (67.19 μg TPF/g/day during 2019 and 69.52 μg TPF/g/day during 2020) and Phosphomonoesterase activity (78.61(μg PNP/g/hr 2019 and 79.48 μg PNP/g/hr during 2020 were reported with application of RDK through banana pseudo stem vermicompost along with mustard oil cake @ 20 kg ha-1 (T8) followed by application of RDK through azolla incorporation along with mustard oil cake @ 20 kg ha-1 (T6). In the present investigation, the gross monetary return (`.127136), net monetary return (`.79136) and B:C ratio (2.65) were found to be highest under T8 treatment i.e. RDK through banana pseudo stem vermicompost + mustard oil cake @ 20 kg ha-1 and the lowest were recorded under T1 treatment. Based on the findings of two years study on management of potassium in organic black rice under system of rice intensification, it may be concluded that among all treatments T8 (RDK through banana pseudo stem vermicompost + mustard oil cake @ 20 kg ha-1) was found best closely followed by treatment T6 (RDK through azolla incorporation along with mustard oil cake @ 20 kg ha-1) with respect to reap good economic yield with better quality, sustain the soil health and high net return and were found beneficial as potash source to substitute recommended dose of potassium in organic cultivation of black rice under agro-ecological situation of Assam.ThesisItem Open Access AGRO-PEDOLOGICAL ASSESSMENT OF THE TRADITIONAL AGARWOOD (Aquilaria malaccensis) GROWING AREAS OF UPPER BRAHMAPUTRA VALLEY ZONE, ASSAM(2022) Bordoloi, Anshuman; Dutta, SamironThe present investigation was carried out in some traditional Agarwood growing areas of the Upper Brahmaputra valley zone of Assam for pedogenic characterization of the soils and to evaluate the soil fertility status and microbial properties of soils around the Agarwood trees of high and low market values. The plant nutrient content and biochemical properties of the leaf of both types of trees were also determined and their relation with soil properties was assessed. An attempt was also made to evaluate the influence of different soil and plant properties on the quality of Agar trees of the area. To accomplish the objectives, ten locations were selected from three districts of the Zone. The highest number of locations (six) were selected in Golaghat district (Dhekial, Kakodunga, Naharani, Haanhpani, Podumoni, and Halowagaon) because of its largest area under Agarwood production. Out of the remaining four locations, two were selected in Jorhat (Alengi and Pirakota) and the other two were taken from Sivasagar district (Namti and Mathurapur). A soil profile was exposed in each location to characterize and classify the soils. Besides 120 numbers of composite surface (0-25 cm) and subsurface (25-50 cm) soil samples were collected from near the trunk of good and poor quality agar trees of all the locations. In addition to soil samples, equal numbers of plant samples were also collected from these trees for the present study. The soils were dark yellowish-brown to brownish-yellow in colour and loam to clayey in texture. The sand, silt, and clay content of the soil profiles varied from 28.1- 54.5%, 19.6 -37.3%, and clay 22.7-42.8% respectively. Soil structure was mostly weak to medium sub-angular blocky. The bulk and particle density of the soils ranged from 1.19 -1.59 Mg m-3 and 2.48-2.61 Mg m-3 respectively. The average water holding capacity of the soils was found to be greater than 30%. The soils were very strongly acidic to slightly acidic with a pH range from 4.79 to 6.60 and found to increase with the depth of soils. The organic matter content of the soils was invariably high (>0.75%) in the surface horizons which decreased regularly with the depth of soils. The free Fe and Al oxides of the soils varied from 1.43-2.93% and 0.37-0.85% respectively. Among the exchangeable cations Ca was the most dominant cation followed by Mg, Na, and K. The CEC of the soils was quite low with a range from 7.8 to 10.5 cmol(p+)kg-1. The exchange acidity, Total acidity, and extractable Al of the soils varied from 1.38 -3.37, 2.22-4.28, and 2.04- 3.35 cmol(p+)kg-1respectively. The exchangeable Al contributed more than 80% of the exchange acidity of the soils. The average Al saturation was found to be more than 30% in all the soils. The morphological and physicochemical properties of soils indicated the development of a cambic horizon in the studied soils. Based on these properties, all the soils were classified as Typic Dystrudepts at the subgroup level except soils of Namti and Mathurapur of Sibasagar district which were classified as Ruptic Alfic Dystrudepts due to higher base saturation in lowermost horizons. The properties determined in composite soil samples showed significant variation among the different locations. The pH and organic carbon of the surface and subsurface soils ranged from 4.97 -5.80 and 1.08-1.37% respectively. The available N and P of the soils were medium on the surface while low to medium in subsurface soils. The status of available K was low to medium. The Ca and Mg content of the surface soils varied from 2.05-2.38 and 1.03-1.40 cmol(p+)kg-1 and in subsurface they ranged from 1.66-3.04 and 0.71-1.10 cmol(p+)kg-1 respectively. The content of S, Fe, Mn, Zn, and Cu of all the soils irrespective of depth was found to be sufficient barring a few irregularities. The B content however was deficient in all the soils (< 0.50 mg kg-1). The MBC and MPS of the surface soils varied from 455.44-827.31 and 6.09-7.43 and 327.36-668.37 and 5.54-7.69 in subsurface soils respectively. Most of these parameters showed significant variation between the soils under good and poor quality Agarwood trees except N, Ca, Mg, S, Fe, and Mn of soils. The nutrient content of leaf, bark, and wood showed significant variation among different locations. The range of nutrients for leaf N, P, K, Ca, Mg and S were 2.12 – 2.475 %, 0.176- 0.187 %, 0.558-0.629 %, 0.367- 0.475 %, 0.275-0.282 % and 0.034- 0.052 % respectively. The N, P, K, Ca, Mg and S of bark ranged from 1.152–1.477 %, 0.060-0081 %, 0.396-0.491 %, 0.329-0.446 %, 0.127-0.180 % and 0.019-0.028 % respectively. Similarly in wood these nutrients varied from 0.315- 0.516%, 0.062 - 0.081 %, 0.147 to 0.208 %, 0.231- 0.365 %, 0.120 – 0.226 % and 0.014-0.020% respectively. It was observed that the difference in concentration of the nutrients in soil under trees with good and poor health differ significantly and was found to be higher in soils under the tree with poor health. A similar observation was also made in the biochemical properties of the leaf. A significant relationship was observed between the plant nutrient concentration and nutrient content of soils. The biochemical properties also showed an identical relationship barring a few exceptions. An attempt was made to evaluate the influence of different soil properties, plant nutrient concentration, and biochemical properties on the quality of Agarwood trees through PCA. The PCA identified MBC, microbial population, the content of Zn, Cu, available P, available K, and organic carbon as the major soil factor that might have played crucial role in determining the quality of Agarwood trees. In addition to these soil factors, the nutrient concentration of bark and wood, concentration of secondary nutrients in leaf, and biochemical properties like total carbohydrate, chlorophyll-A, total chlorophyll, and residual sugar might be the other important plant factors determining the resinwood quality of Agarwood trees. Interestingly the content of all these properties identified through PCA was higher in the soils collected from near the trunk of trees with poor health and the plant samples collected from such plants. The pH and content of Zn in surface soils, MBC, and microbial populations were an exception.
