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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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20233
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Subject: Agricultural Meteorology × End date: 2023 × Start date: 2023 ×
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    ThesisItemOpen Access
    COMPARATIVE ASSESSMENT OF INSECT PEST- DISEASE DYNAMICS AND THE PERFORMANCE OF GREEN GRAM UNDER DIFFERENT MICROCLIMATES
    (2023) Yadav, Roshani; Medhi, Kuldip
    Field experiments were conducted in the Instructional-Cum-Research (ICR) Farm of Assam Agricultural University, Jorhat during kharif, 2022 and summer, 2023 with an objective to study the seasonal variation in incidence of insect pests and disease dynamics of green gram, and also to assess the performance of four cultivars of green gram viz., SGC 16, SGC 20, IPM 02-3 and MH 421 under three different microclimates created by manipulating sowing dates. The crop was sown on 11 September (D1), 28 September (D2) and 13 October (D3) during kharif, 2022, whereas it was sown on 13 February (D1), 28 February (D2) and 14 March (D3) during summer, 2023. The results revealed that aphid (Aphis craccivora) and jassid (Empoascakerri) population on green gram reached its peak in 50th and 42nd SMW, respectively in kharif season and 18th SMW in summer season. Pod borer (Helicoverpaarmigera) population recorded highest in 44th SMW during kharif and 20th SMW in summer seasons. Likewise, whitefly population (Bemisiatabaci) was recorded maximum in 46th and 16th SMW during kharif and summer seasons, respectively. In addition, Cercospora leaf spot (Cercospora canescens) and Moongbean Yellow Mosaic Virus (MYMV) disease infection reached its peak during 45thSMW in kharif and, 20th and 18th SMW, respectively during summer season. The Percent Disease Index (PDI) of Powdery mildew (Erysiphe polygoni) and Anthracnose (Colletotrichum sp.) was recorded highest in 51st SMW during kharif and 23rd SMW in summer season. In summer green gram, aphid population was significantly and positively correlated with maximum (0.55*) and minimum (0.45*) temperature; while it had a significant negative correlation with minimum temperature (-0.65**) duirng kharif season. Jassid and whitefly had positive and significant correlation with maximum and minimum temperatures. None of the weather variable had a significant impact on pod borer population during both of the season.Likewise, Cercospora leaf spot exhibited significant and positive correlation with temperature atripening phase in kharif green gram. The reliability of regression model (R2) developed based on insect pest and disease weather relationship were found to be varied within 0.04 to 0.77 and 0.24 to 0.85, respectively. The results revealed that among the varieties, MH 421 (539.1 kgha-1) performed better during kharif, whereas least yield (410.9 kgha-1) was observed when sown as summer crop. Poor performance of MH 421, can be indirectly referred from a depletion of 26.9% of intercepted PAR (iPAR) in summer crop relative to kharif crop due to low canopy growth. In contrary, SGC 16 maintained its performance in both kharif (491.2 kgha-1) and summer (512.5kgha-1) seasons. Mainly, substantial difference in plant height, LAI, above ground biomass and number of pods per plant corresponding to early and late sowings during kharif and summer, respectively defines the yield of the crop. In case of early (D1) sowing date, sufficient moisture is available during kharif season, whereas less moisture is available in summer season for supporting initial crop establishment. The mean percentage of iPAR was found 3.4% (SGC 16), 8.4% (SGC 20) and 9.6% (IPM 02-3) higher under late (D3) sown summer season crop relative to kharif season. Overall, protein content in seeds of green gram varied from 22.07 to 24.50%, irrespective of sowing dates and found maximum in SGC 20 (>24.0%); and minimum in SGC 16 (22.0%) in kharif and MH 421 (21.6%) in summer. Maximum protein content was recorded in D2 (23.8%) and D3 (23.9%) corresponding to kharif and summer season, respectively. Moreover, negative association was observed among seed yield and protein content of seedsof green gram.
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    ThesisItemOpen Access
    AGRO-CLIMATIC CHARACTERIZATION FOR PLANNING SMART AGRICULTURAL PRACTICES IN ASSAM
    (2023) Kakoti, Mriganko; Deka, Rajib Lochan
    The present study was undertaken with the objective to characterize the agroclimatic environment for improved planning of agricultural practices in Assam by calculating assured weekly rainfall at different probability levels along with occurrence of dry and wet spell and estimation of moisture availability index which will help in accessing the crop growing duration as well as planning suitable agricultural practices in the region. Long- term rainfall data for a span of 31 years (1991-2021) across 33 designated stations located at six agro-climatic zones of Assam were gathered from IMD, Pune. However, the daily temperature data (maximum and minimum) for the same period were not available in the IMD dataset for all the selected stations. To compensate for this missing information, daily temperature data was obtained from the NASA POWER (Prediction of Worldwide Energy Resources) data portal. The amount of weekly rainfall at different probability levels (90%, 75% and 50%) were calculated using incomplete gamma distribution model and Markov chain model was used to find out the probabilities of occurrences of 2 and 3 consecutive wet weeks or dry weeks by taking threshold limit of 20 mm of rainfall per week. Characterization of rainfall revealed that annual mean rainfall was highest at Karimganj (3397 mm) followed by Lilabari (3182 mm), Kokrajhar (3170 mm), Silchar (3104 mm), Gharmura (3095 mm) and lowest was observed at Lumding (1305 mm) followed by Bokajan (1341 mm). The coefficient of variation (CV %) of annual rainfall varied from 12.4 % to 24.9 % in Lower Brahmaputra valley zone (LBVZ), 13.1 % to 18.1 % in North Bank plains zone (NBPZ), 15.1 % to 18.9 % in Central Brahmaputra valley zone (CBVZ),11.4 % to 18.3 % in Upper Brahmaputra valley zone (UBVZ), 13.2 % to 26.8 % in Hills zone (HZ) and 17.3 % to 27.4 % in Barak valley zone (BVZ) during 1991-2021 indicating rainfall was highly dependable and less erratic in LBVZ, NBPZ, CBVZ and UBVZ as compared to HZ and BVZ which showed high CV. Seasonal rainfall analysis revealed that contribution of monsoon season rainfall to the total annual rainfall was highest (66 %) followed by premonsoon season rainfall (26%), post-monsoon (7%) and winter (2%). Rainfall during postmonsoon and winter were highly variable as CV (%) was more than 45% and 50%. The weekly rainfall data indicated that rainfall was mainly concentrated between 16th to 38th SMW and more than 20 mm of assured rainfall was received during this period at 75% probability level. However, in some stations under Kamrup (R), Kamrup (M) and Sonitpur district this period was between 16th to 35th SMW while the stations under rain shadow belt like Lumding, Golaghat and stations of eastern Karbi Anglong district the period was between 19th to 36th SMW. From 42nd SMW onwards less than 10 mm of weekly rainfall was received at 75% probability level across all the designated stations. The probable occurrence of two consecutive wet weeks increased from 15th, 16th to 38th SMW across all the stations except this period was less for stations under Kamrup (R), Kamrup (M) and Sonitpur district (NBPZ) and for stations located under the rain shadow belt (18th to 38th SMW). Occurrence of dry weeks probability was more than 50% from 43rd SMW across all the stations which corresponds with the growing season of rabi crops in the region. The weekly Moisture Adequacy Index (MAI) values were determined by computing the ratio of AET to PET. PET values were estimated using Thornthwaite's (1948) method, while AET values were derived from Thornthwaite and Mather's (1955) water balance model. This calculation allowed us to assess the availability of moisture in the study area on a weekly basis. Assam comprises of a mixture of different types of soil types. For crop planning and suggesting suitable practices, major two types viz., sandy loam soil having 100 mm water holding capacity and silt clay loam soil with 200 water holding capacity were considered and accordingly MAI was calculated. MAI value increased from 0.4 in rabi season and reaches maximum value of 1 during kharif season indicating enough moisture to support water demanding crops. Almost in most of the stations there was greater chance for water surplus during monsoon season thus offer opportunity for water harvesting and supplemented irrigation to mitigate moisture stress conditions. It can prove beneficial for successive rabi crops also. Soil with high water holding capacity i.e., 200 mm WHC had higher MAI value in all the seasons as compared to soils with l00 mm WHC. The weekly MAI suggests the possibility of sowing kharif crops without affecting the later rabi crops. The length of growing period (LGP) calculated over the period 1991-2021 revealed that the lowest average LGP of 239 days was found in stations of Hills zone and the highest average LGP of 303 days was found in stations of BV zone. When averaged over 31 years, it was observed that the mean LGP accounts for 277 ± 31 days with RF/PET ratio greater than 0.5 and MAI value ranging more than 0.75. The weeks in which the RF/PET ratio was greater than 0.25 with MAI value ranging from 0.4 to 0.75 indicated the presence of residual soil profile moisture. Based on these approaches, pre sowing cultivation, seed bed preparation, sowing and transplanting window was suggested for different agroclimatic zones of Assam.
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    ThesisItemOpen Access
    EVALUATION OF FINGER MILLET GENOTYPES AS CLIMATE SMART CROP UNDER THE AGROCLIMATE OF JORHAT
    (2023) Boruah, Angita; Deka,Rajib Lochan
    A field experiment was conducted during kharif, 2022-23 at Instructional cum Research (ICR) Farm of Assam Agricultural University, Jorhat to study crop weather relationship and genetic diversity among five finger millet genotypes viz. Gossaigaon Maruadhan (V1), FMAVT 4001 (V2), FMAVT 4006 (V3), FMAVT 4007 (V4) and FMAVT 4012 (V5) grown under three microclimatic regimes: 6th August (D1), 22nd August (D2) and 6th September (D3), following split plot design with three replications. The weekly mean maximum (Tmax) and minimum temperature (Tmin), rainfall (RF), morning (RH-I) and evening relative humidity (RH-II), bright sunshine hours (BSSH), pan evaporation (EVP) and wind speed (WS) ranged from 22.1ºC to 34.9ºC, 7.9ºC to 25.6ºC, 0 to 104.4 mm, 91 to 100%, 51 to 85%, 1.9 to 9 hours, 1.1 to 3.8 mm and 0.8 to 3.1 kmph respectively during the period of experimentation. Biometric observations, viz. plant height, leaf area index (LAI), biomass, number of effective tillers/m2, number of earheads/m2, number of fingers per earhead, finger length, test weight, grain and straw yield were recorded periodically during entire growing season and at the time of harvest. Soil temperature at 10 cm depth was recorded daily, soil moisture at 15 days interval and incident, reflected and transmitted photosynthetically active radiation (PAR) at 7 days interval were also recorded during the experimental period. Results revealed that LAI, plant height and biomass at all the growth stages differed significantly under different microclimatic regimes with highest values recorded in the early sown (D1) crop. Accumulated agroclimatic indices such as GDD (growing degree days), HTU (heliothermal units) and PTU (photothermal units) decreased gradually with successive delay in sowing time with highest value being recorded under D1. Yield attributes and grain yield were found highest in early sown crop (D1) as compared to late sown crops. The vegetative phase of the first sown (D1) crop was exposed to comparatively higher soil temperature regime as compared to late sown crops (D2 and D3). The crop sown on 6th August (D3) had the highest PAR interception rate (72.6%). Among the genotypes, Gossaigaon Maruadhan (V1) was found to be superior with respect to growth parameters and yield (17.94 q/ha). Correlation analysis revealed that yield attributes and yield were significantly positively correlated with Tmax, Tmin, and WS whereas the correlation was negative and significant with RHI during all growth phases. EVP and BSSH had significant positive association with yield and yield attributes in all the phases of the crop growth except during reproductive phase. Yield predictive models were developed by utilizing step-wise multiple regression method using mean and accumulated agroclimatic indices during different pheno phases and entire period of crop growth. The most efficient yield predictive model among mean phasic meteorological parameters was found with Tmin during vegetative phase with highest coefficient of determination (R2=0.932) irrespective of varieties. While, among the accumulated meteorological indices, the best models were found for PTU (R2=0.932) and RF (R2=0.932) during vegetative phase and entire growing period respectively. For genetic diversity analysis, 20 RAPD primers were used out of which 7 were found to be polymorphic. These markers amplified 46 alleles with an average of 4.6 alleles per marker. Genetic relationship among finger millet genotypes were found out on the basis of pairwise Jaccard’s similarity coefficient whose value ranged from 0 to 0.6 with an average of 0.295. Cluster analysis by UPGMA method grouped 20 samples into two major clusters, each further sub-divided into two sub-clusters. Cluster A comprised of 15 samples while cluster B had only 5 samples. All the treatment combinations of varieties V2, V3, V4 and V5 were grouped in cluster A, while treatment combinations of V1 were grouped in cluster B which indicates their genetic dissimilarity. These results indicated that different plant characters exhibiting strong positive genotypic and phenotypic correlation with grain yield can be used for development of high yielding genotypes of finger millet crop.