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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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ThesisItem Open Access Effect of entomopathogenic fungi, Metarhizium anisopliae on growth and yield of french bean(AAU, Jorhat, 2017-07) Kurmi, Himanshu; Das, K.Experiments were carried out during September, 2016 to March, 2017 in the Department of Crop Physiology, Assam Agricultural University, Jorhat-13, to evaluate the effects of different concentrations of fungal isolate of Metarhizium anisopliae on french bean. In one experiment, fungal isolates of M. anisopliae at 105cfu/ml, 106cfu/ml, 107cfu/ml and 108cfu/ml concentrations were tested to determine their effects on germination and subsequent seedling growth of french bean under laboratory condition. It was observed that germination percentage, germination index, vigour index, shoot and root length, fresh and dry weight of shoot and root were affected by M. anisopliae isolates in a concentration dependent manner. Among the applied concentrations, 106cfu/ml and 107cfu/ml concentrations were found to be more stimulatory compared to control. Another experiment was conducted in field condition with these two concentrations (106cfu/ml and 107cfu/ml concentrations) to evaluate their effects on growth and yield of french bean. Three different modes of application, viz. seed treatment (before sowing), foliar application (15 DAS, 30 DAS and 45 DAS) and combination of seed treatment and foliar application were employed. Recorded data revealed that plant growth of french bean in terms of plant height, leaf number, leaf area, root volume, shoot and root dry weights were increased by M. anisopliae. Physiological parameters such as relative leaf water content, total chlorophyll content and leaf N P K content of french bean were also positively influenced by the fungal isolate. However, no significant alteration was recorded in leaf proline content irrespective to mode of application and concentration of fungal isolate. Among the different treatments, 107cfu/ml concentration was found to be more stimulatory when applied as combination of seed treatment and foliar spray. At this treatment combination, pronounced stimulatory effects were recorded on yield and different yield attributing parameters of french bean. From the results of this investigation, it can be concluded that in addition to its well established protective role against insect pest, M. anisopliae also exhibits stimulatory effects on growth, development and yield of the crop.ThesisItem Open Access EVALUATION OF PHYSIOLOGICAL PERFORMANCE OF LENTIL GENOTYPES IN ORGANIC SITUATION UNDER DEFERRED DATES OF SOWING IN RICE FALLOW LAND(AAU, Jorhat, 2017-01) Sarmah, Bhargob; Kalita, PrakashAn investigation was carried out during November, 2016 to March, 2017 in the Instructional-cum-Research (ICR) farm and Department of Crop Physiology, Assam Agricultural University, Jorhat-13, to evaluate the physiological performance of lentil genotypes in organic situation under deferred dates of sowing in rice fallow land. Five lentil genotypes namely HUL-57, SLC-102, PL-406, KLS-218 and SLC- 101were used for the study. There were three dates of sowing viz. 15th November, 30th November and 15th December. The land used for raising the crop has been maintained for last ten years as organic plot and has been used for raising winter rice crop. The lentil crops raised were supplied with nutrients through organic inputs (well rotten cow dung and enriched compost) and the chemicals used for plant protection were also organic. Significant variations were recorded among the genotypes in terms of various parameters namely total leaf chlorophyll content, relative leaf water content, in- vivo leaf nitrate reductase activity, root: shoot ratio, dry matter partitioning, number of pod per plant, number of seeds per pod, grain yield and harvest index .These parameters exhibited a decreasing trend with delay in the date of sowing from the recommended one. However lipid peroxidase activity was found to increase due to delay in sowing of lentil genotypes. Among the genotypes the HUL-57 performed the best compared to the other genotypes under both the situations when sowing was done at recommended date of sowing and when the sowing was delayed. On the other hand the genotype SLC-101 registered the lowest performance. The genotype HUL-57 exhibited the lowest percent reduction in terms of total leaf chlorophyll content, relative leaf water content, in- vivo leaf nitrate reductase activity, root: shoot ratio, dry matter partitioning, number of pod per plant, number of seeds per pod, grain yield etc. followed by the genotype KLS-218. When the sowing was delayed by 15 days (30th November) on an average biomass and grain yield were decreased by 12.29% and 3.30% respectively, whereas the corresponding decreases were 35.49% and 13.53% when biomass and grain yield from 15th December sowing were compared with that of 15th November sowing. In case of HUL-57 the decrease in biomass and grain yield were only 33.97% and 12.11% respectively when performance under 15th December sowing were compared with that of 15th November sowing. The better performance of HUL-57 could be attributed to better performance of this genotype in terms of the parameters namely total chlorophyll content, relative leaf water content, in- vivo leaf nitrate reductase activity, root: shoot ratio, dry matter partitioning, number of pod per plant, number of seeds per pod etc. As with the delay in sowing resulted in the exposure of the lentil plants to moisture shortage coinciding with the vegetative and early reproductive stages, the genotype HUL-57 can be labeled as moisture shortage tolerant genotype; more over this genotype can be said to have adjusted efficiently under the decreasing length of photo period as encountered when sowing was delayed.ThesisItem Open Access PHYSIOLOGICAL BASIS OF SUBMERGENCE TOLERANCE IN LOWLAND RICE(AAU, Jorhat, 2017-07) Talukdar, Krishna; Das, RanjanThe experiment was conducted for two years during Kharif season 2016 and 2017. About 200 genotypes from different adaptations were collected and screened for submergence tolerance by SES scoring developed IRRI, Philippines. After screening, five genotypes viz. Tejai longpi, Marjina, Badam bao, Sok langlu and OM5451 were selected based on survival, recovery characteristics and comparing with submergence susceptible line IR-64. Significant variation was observed amongst the genotypes for all the parameters viz. lipid peroxidation, leaf soluble protein content, leaf temperature and Membrane Stability Index, Chlorophyll Stability Index, Nitrate Reductase Activity. However, a significant increase in MDA content, root volume, root: shoot ratio was observed under stress condition. Stress induced reduction in stem elongation and plant height was found highest in Badam bao which could be correlated to an increase in total carbohydrate content in the genotype. Badam bao also recorded the lowest reduction in total chlorophyll content and tiller number under submerged condition. It can be assumed that Badam bao being a tall variety has got an inherent capability to cope submergence stress by reducing stem elongation and increasing tiller number thereby increasing yield. In the present study, under submerged condition, Badam bao could maintain its yield and yield attributes in terms of 1000 grain weight and no. of grain /panicle. This could be correlated with a significant increase in flag leaf area in the genotype. Modern high-yielding rice varieties are highly susceptible to flooding whereas traditional cultivars have acquired moderate tolerance to flooding but they carry the penalty being of inherently lower grain yields. Therefore, in the present investigation, it was found that two traditional genotypes viz. Badam bao and Marjina could be grown successfully under submerged condition with moderately higher yield.ThesisItem Open Access RESPONSE OF BLACK GRAM GENOTYPES TO PLANT GROWTH REGULATORS UNDER LATE SOWN CONDITIONS(AAU, Jorhat, 2018-07) Baishya, Navanita; Kalita, PrakashA pot experiment was carried out during the kharif season of 2017 with five black gram genotypes in the stress physiology premises of Department of Crop Physiology, AAU, Jorhat-13. Five black gram genotypes viz., LBG-752, PU-30, PU-40, AZAD URD-3 and LBG-645 were sown at three different dates viz., 15th September (recommended date of sowing i.e. D1), 1st October (15 days delayed beyond recommended date of sowing i.e. D2), and 15th October (30 days delayed beyond recommended date of sowing i.e. D3) and were treated with water spray (control), 50 ppm GA3 and 500 μ mole/lit salicylic acid at 20 DAS and 15 days there after. The objectives of the experiment was to evaluate the physiological performance of black gram genotypes under late sown situation and to examine the influence of some plant growth regulators in improving productivity of black gram genotypes under late sown conditions .Significant variations were recorded due to the genotypes, treatments (plant growth regulators) as well as dates of sowing in terms of various parameters namely leaf area, leaf number, plant height, root volume, root surface area, root length, number of nodules, whole plant biomass, leaf total chlorophyll content, in vivo leaf nitrate reductase activity, lipid peroxidase activity, proline content, number of pods per plant, number of seeds per pod, seed yield and harvest index. The interaction between genotypes and growth regulator treatments was also found to be significant for these traits. The genotypes responded differently towards the dates of sowing for the traits namely leaf area, plant height, root volume, root surface area, whole plant biomass, total chlorophyll content, lipid peroxidase activity, hundred seed weight and seed yield and the interaction among genotypes, plant growth regulators and sowing dates was found to be significant in terms of plant biomass content at harvest. In general, all the traits excepting lipid peroxidase activity exhibited a declining trend with delayed dates of sowing compared to that of recommended date of sowing. The genotype LBG-645 showed the best yield performance followed by AZAD URD-3 when sowing was done in the recommended date as well as in delayed dates. On the other hand, the genotype PU-40 registered the lowest yield performance in both the situations. The GA3 treated plants showed the best performance for most of the traits as compared to salicylic acid treated plants and water spray under all the sowing dates. The combination of LBG-645 with GA3 treatment recorded the best results for most of the traits under all the three dates of sowing. In the case of the recommended date of sowing, the values of seed yield in LBG-645, AZAD URD-3 and PU-40 with GA3 treatment were 12.96 g plant-1, 10.39 g plant-1, 5.96 g plant-1 respectively. With second date of sowing (1st October) the corresponding seed yield values were 11.18 g plant-1, 7.04 g plant-1, 4.75 g plant-1 respectively. When the sowing was done on 15th October, the GA3 treated plants of LBG-645, AZAD URD-3 and PU-40 recorded 8.61 g plant-1, 4.53 g plant-1, 4.51 g plant-1 respectively. The higher values of grain yield in LBG-645 with applied GA3 may be related to its better performance for the traits namely leaf area, root surface area, whole plant biomass, leaf total chlorophyll content, in-vivo leaf nitrate reductase activity and harvest index. From the correlation study also positive and significant correlations were recorded in D1, D2 and D3; between seed yield and leaf area (0.770**, 0.695**, 0.727**), seed yield and root surface area (0.736*, 0.796**, 0.541**), seed yield and whole plant biomass (0.790**, 0.638**, 0.723**), seed yield and total leaf chlorophyll content (0.833**, 0.805**, 0.673**), seed yield and in-vivo leaf nitrate reductase activity (0.813**, 0.784**, 0.705**), seed yield and harvest index (0.983**, 0.083**, 0.987**).ThesisItem Open Access MORPHO-PHYSIOLOGICAL PERFORMANCE OF SOME LENTIL GENOTYPES IN RESPONSE TO ORGANIC MANURE SOURCES(AAU, Jorhat, 2018-07) Borah, Horipriya; Kalita, P.A field experiment was conducted during the rabi season of 2017-18 at ICR farm (organic block) of AAU, Jorhat-13. Five lentil genotypes were evaluated for their morpho-physiological performance in response to three different sources of organic manure. The genotypes were HUL-57, SLC-102, SLC-101, KLS-218 and PL-406 which were collected from Regional Agricultural Research Station, AAU, Shillongani, Nagaon and the souces of organic manure were FYM, vermicompost and poultry manure. The recommended package of practices for lentil under Assam situation were followed for raising the crop . The recomended levels of N, P and K were supplied with various organic manure sources. Significant variations were recorded among the genotypes as well as sources of organic manure at both the stages of observation in relation to the various traits viz plant height, leaf biomass, root biomass, whole plant biomass. The traits viz. root volume, root surface area, nodules number, stem biomass ,reproductive biomass, in-vivo leaf nitrate reductase activity, total chlorophyll content of leaf, lipid peroxidation, leaf nitrogen content, leaf phosphorus content showed significant variation due to genotypes as well as organic manure sources at active pod filling stage only. At harvest number of pods per plant, 100 grain weight, grain yield and harvest index also exhibited significant variation due to genotypes as well as sources of organic manure.The interaction between genotypes and manure sources were found to be significant for the traits viz leaflet number per plant for both the stages of observation and stem biomass at 50% flowering and leaf proline content at active pod filling stage. Highest values of these traits were recorded in the plants supplied with vermicompost followed by poultry manure and FYM except the trait of lipid peroxidase activity which showed just the opposite trend. The genotype KLS-218 with vermicompost treatment recorded the highest plant biomass and grain yield at harvest. This increase in grain yield was 9.1% and 6.8% with vermicompost over FYM and poultry manure respectively. The highest grain yield in KLS-218 may be attributed to the higher values in the traits like relative leaf water content, leaflet no per plant, nodule no per plant, leaf biomass, stem biomass, reproductive biomass, whole plant biomass, nitrate reductase activity, total leaf chlorophyll content, proline content, leaf nitrogen content, leaf phosphorus content, no of pods per plant, no of seeds per pod, 100 grain weight and harvest index. From the correlation study positive and significant correlation were recorded between seed yield and relative leaf water content (0.772**), seed yield and leaflet no at 50% flowering(0.887**), seed yield and leaflet no at active pod filling stage (0.790**, seed yield and nodule no (0.911**), seed yield and leaf biomass at 50%flowering (0.891**), seed yield and leaf biomass at active pod filling stage (0.854**), seed yield and stem biomass at 50%flowering (0.909**), seed yield and stem biomass at active pod filling stage (0.908**), seed yield and whole plant biomass at 50%flowering (0.935**), seed yield and whole plant biomass at active pod filling stage (0.967**), seed yield and reproductive biomass (0.924**), seed yield and nitrate reductase activity (0.883**), seed yield and total chlorophyll content (0.873**), seed yield and proline content (0.895**), seed yield and leaf nitrogen content (0.923**), seed yield and leaf phosphorus content (0.878**), seed yield and no of pods per plant(0.919**), seed yield and no of seeds per pod(0.892**), seed yield and 100 grain weight (0.907**) and seed yield and harvest index (0.979**). The genotype KLS-218 registered highest benifit cost ratio i.e 1.43, 1.52, 1.46 for FYM, vermicompost and poultry manure respectively and this genotype can be recomended for Assam condition with the supply of N,P and K through vermicompost.ThesisItem Open Access RESPONSES OF SOME WHEAT (Triticum aestivum L.) GENOTYPES TO AEROSOLS OF NITROGEN(AAU, Jorhat, 2018-07) Borgohain, Eshani; Bharali, BhagawanWheat (Triticum aestivum L.) is one of the most important cereal crops globally, and it is a staple food for about one third of the world’s population. Cultivation of wheat has been the symbolic of green revolution that played pivotal role in making the nation a food surplus nation. The importance of wheat in Indian Agriculture is second to rice. The investigation into the effects of Nitrogen aerosols on some wheat (Triticum aestivum L.) genotypes (viz., 306, 1544, LOK-1, SHRI RAM-273), was accomplished both under field (October, 2016-March, 2017) and pot culture (October, 2017-March, 2018) at ICR farm and at the vicinity of Stress Physiology Laboratory, Department of Crop Physiology, Assam Agricultural University, respectively. The main objective of the investigation was to evaluate the physiological traits in wheat fertilized with Nitrate aerosols under field condition. The study, too, looked into the action mechanism of Nitrogen aerosol altering the physiology of wheat crop, and the relations between economic yield, physiological attributes and nitrogen status of wheat crop under the influence of aerosols. Treatments were applied at three stages viz., seedling, maximum tillering and spike initiation stages. The aerosols @ 400 ppm (≈40 kg N ha-1), were applied in three times i.e. 1200ppm or 1.2% (on sunny days in the afternoon (after 2–3 P. M.) when air temperature was low. In the field experiment, at maximum tillering and spike initiation stages, almost all the Nitrogen aerosols as compared to control increased the parameters significantly in a range viz., leaf area (8-13%) and (6-15%), LAI(19-31%) and (25.08-31.43%), SLW (11-26%), tiller numbers (14-28%) and (16-24%), effective tillers (19-31%), plant height (3-6%), rate of Pn (9-19%) and(10-16%), total chlorophyll content (14-34%) and (19-31%), chlorophyll a content (16-45%) and (23-35%), chlorophyll b content (14-33%) and (17-29%), NR activity (12-25%) and (23-36%), lipid peroxidase (6-53%) and (2-9%), CMS (14-28%), total carbohydrate content (18-28%), N content in grains (18-37%), NUE (26-39%), intercellular [K+] (13-31%), exchangeable [K+] (14-32%), intercellular [Ca2+] (11-28%) and exchangeable [Ca2+] (8-17%). The aerosols also increased the yield attributes such as no. of seeds per spike (2-7%), length of spike (14-24%), spike weight (14-18%), test weight (4-10%), harvest index (1.23-5.38%), biological yield (2-3%) and economical yield (3-8%). However, CMS was reduced non-significantly as compared to control at spike initiation stage. In the pot experiment, too, as compared to control, almost all the Nitrogen aerosols increased the parameters significantly in a range at maximum tillering stage and at spike initiation stages, respectively viz., leaf area (8-14%) and (4-10%), LAI (11-25%) and (11-21%), SLW (11-20%), tiller numbers (12-21%) and (10.68-16.66%), effective tillers (14.83-21.25%), plant height (5-8%), rate of Pn (16.78-23.43%) and (18-24%), total chlorophyll content (22-39%) and (26-33%), chlorophyll a content (22-43%) and (34-41%), chlorophyll b content (22-37%) and (23-30%), NR activity (14-28%) and (7.39-14.26%), lipid peroxidase (4-16%) and (2-9%), CMS (12-42%) and (12-26%), total carbohydrate content (7-16%), N content in grains (18-39%), NUE (25-42%), intercellular [K+] (21-44%), exchangeable [K+] (8-18%), intercellular [Ca2+] (7-24%) and exchangeable [Ca2+] (11-21%) . The aerosols also increased the yield attributes such as no. of seeds per spike (2-6%), length of spike (12-22%), spike weight (7-15%), test weight (5-9%), harvest index (2-7%), biological yield (2-7%) and economical yield (6-11%). In the field experiment, the variety LOK-1 possessed the highest score (25) followed by SHRI RAM-273 (10), and 1544 and 306 (2) considering their responses to the aerosols at maximum tillering, spike initiation and harvest stages. In the pot experiment, the variety LOK-1 possessed the highest score (28) followed by 1544 (4), SHRI RAM-273 (3) and 306 (2). However, based on the overall performance of the varieties at field and pot experiments together, the variety LOK-1 possessed the highest score (53) followed by SHRI RAM-273 (13), 1544 (6) and 306 (4). Thus, it could be concluded that the variety LOK-1 emerged as the most physiologically efficient one in the experiments. The physiological characteristics supporting the holistic performance of the variety LOK-1 especially are higher leaf area (12.90 cm2 plant-1) and (16.92 cm2 plant-1), LAI (1.63) and (0.99), effective tillers (2.69) and (3.89), rate of net photosynthesis (8699.76 ppm CO2 absorbed g-1d.w.h-1) and (9042.73 ppm CO2 absorbed g-1d.w.h-1), total chlorophyll content (2.48 mg g-1 fw of leaf) and (2.59 mg g-1 fw of leaf), chlorophyll a content (0.73 mg g-1 fw of leaf) and (0.80 mg g-1 fw of leaf), chlorophyll b content(1.68mg g-1 fw of leaf) and (1.73 mg g-1 fw of leaf), nitrate reductase activity (17.21 nmol NO2- g-1 fw of leaf hr-1) and (33.16nmol NO2- g-1 fw of leaf hr-1), CMS (0.17) and (0.65), carbohydrate content (147.63 mg g-1 dw) and (144.84 mg g-1 dw), intercellular [K+] (0.98 mg g-1 fw) and (1.07 mg g-1 fw), exchangeable [K+] (2.03mg g-1 fw) and (1.97 mg g-1 fw), intercellular [Ca2+] (1.66 mg g-1 fw) and (1.61 mg g-1 fw), exchangeable [Ca2+] (8.28 mg g-1 fw) and (8.28 mg g-1 fw), length of spike (10.78 cm) and (11.02 cm), spike weight (1.63 g) and (1.83g), test weight(47.15 g) and (4.57g), harvest index(69.42) and (51.57), biological yield (1.43 t ha-1) and (10.13 g plant-1) and economical yield(0.99 t ha-1) and (5.23 g plant-1) for field and pot respectively. Further as regard to the field application of N aerosols, KNO3 scored the highest (26) followed by Ca(NO3)2 (7), NH4NO3 (5), Control (0) considering the overall scores at maximum tillering, spike initiation and harvest stages. Similarly, in the pot experiment, KNO3 scored the highest (23) followed by Ca(NO3)2 (10), NH4NO3 (4), Control (0). However, based on the overall performance of the varieties at field and pot experiments together, the treatment KNO3 scored the highest (49) followed by Ca(NO3)2 (17), NH4NO3 (9), CONTROL (0). The correlation studies revealed that seed yield in LOK-1 was positively correlated with length of spike (0.63*, 0.97**), spike weight (0.69*. 0.09), harvest index (0.88**, 0.74*), biological yield (0.89**, 0.94*) and N content (0.80**, 0.94**) both for field and pot experiments respectively. In case of aerosol treatments, KNO3 was positively correlated with length of spike (0.97**, 0.55), test weight (0.88**), harvest index (0.96**, 0.79*), biological yield (0.78*, 0.76*) and N content (0.93**, 0.79*) at P (0.05)/ and P (0.01).ThesisItem Open Access Germination, seedling survival, growth and development of rice (Oryza sativa L.) under anoxia(AAU, Jorhat, 2018-07) Paul, Deepjyoti; Das, RanjanThe experiment was conducted for two years during kharif season 2016 and 2017. One hundred and forty six rice genotypes from different ecotypes were collected and screened for submergence tolerance. Out of 146 genotypes, six genotypes viz. Ronga Lahi, Ronga Bao, Bangali Lahi, Suwag Moni Horu, Asra 123 and Asra 8 were selected as anoxia tolerant lines based on germination, survival and growth. After screening, the six genotypes were evaluated to understand the mechanism of tolerance from germination to seedling stage (plastic glasses in tray) and during vegetative and reproductive growth period (plastic pot) under submergence and normal condition in comparison to susceptible genotype IR 64. Significant variation was recorded during anoxic germination among the genotypes. Highest amylase activity viz., alpha amylase and beta amylase, total sugar, non structural carbohydrate was recorded higher in Asra 123 followed by Asra 8 as compared with susceptible genotype IR-64 indicating that sufficient amount of soluble sugar was produced immediately after imbibition due to significant increase of amylase activity at the time of germination particularly in highly tolerant genotypes. Lower stem elongation rate was recorded in genotypes Asra 123, Asra 8 followed by Ronga Lahi and Ronga Bao. This may be related with lower use and more conservation of carbohydrate during submergence to support growth and development after the water recedes. This may be an inherent character of such genotypes which may reflect even after seed formation and this is attributed in our present investigation where more amount of reserve in total soluble sugar were recorded in tolerant genotypes with higher amylase activity in first experiment. Stress induced reduction in stem elongation was found to be highest in Asra 123 followed by Ronga Lahi. Less reduction in grain yield per hill was recorded in Asra 123 followed by Asra 8 because these genotypes could maintain lower stem elongation with more number of tiller production during submergence. Some genotypes have different degrees of submergence tolerance by maintaining higher CSI, MSI, Photosynthesis, chlorophyll content which may help to maintain growth and development under these conditions. The susceptible genotypes invariably reflected more metabolic de-arrangements in terms of photosynthesis rate, nitrate reductase activity, chlorophyll loss and depression of membrane stability due to higher level of MDA content. In the present investigation Asra 123, Asra 8, Ronga Lahi, Ronga Bao, Bangali Lahi and Suwag Moni Horu could grow successfully under anoxic and showed better performance under submergence.ThesisItem Open Access VASE LIFE AND QUALITY OF GLADIOLUS (Gladiolus grandiflora) AS INFLUENCED BY POSTHARVEST CHEMICAL APPLICATIONS(AAU, Jorhat, 2018-07) NATH, DEB JYOTI; Das, KaushikAn investigation was carried out during October, 2016 to March, 2017 in the Department of Crop Physiology, Assam Agricultural University, Jorhat-13, to evaluate the effects of different pulsing treatments and holding solutions on vase life and quality of cut gladiolus spikes. In one experiment the cut gladiolus spikes were pulsed with different concentrations of salicylic acid (50ppm, 100ppm and 150ppm), benzyl adenine (50ppm, 100ppm and 150ppm) and nano silver (5ppm, 10ppm and 15ppm) under laboratory condition. Recorded data revealed that moisture content, fresh and dry weights of cut gladiolus spikes were positively influenced by the pulsing treatments. Amount of solution uptake, transpirational water loss and relative leaf water content recorded in cut gladiolus spikes were also altered significantly by the applied pulsing agents. Total carbohydrate content of petals, chlorophyll content of sepals, anthocyanin content of petals and vase life of cut gladiolus spikes were affected appreciably by pulsing treatments in a concentration dependent manner. Among the applied treatments, salicylic acid 150ppm was found to be the best in increasing the vase life of cut gladiolus spikes. In another experiment cut gladiolus spikes were treated with different concentrations of salicylic acid (50ppm, 100ppm and 150ppm), benzyl adenine (50ppm, 100ppm and 150ppm) and nano silver 10ppm as holding treatments under laboratory condition. Combined effects of nano silver (10ppm) with salicylic acid (50ppm, 100ppm and 150ppm) and benzyl adenine (50ppm, 100ppm and 150ppm) were also evaluated. Recorded data revealed that physiological and biochemical parameters in terms of moisture content, fresh and dry weights, amount of solution uptake, transpirational water loss, relative leaf water content, total carbohydrate content of petals, chlorophyll content of sepals, anthocyanin content of petals and vase life of cut gladiolus spikes were increased by different holding treatments. It was further observed that nano silver application significantly enhanced the efficacy of salicylic acid and benzyl adenine in increasing the vase life of cut gladiolus spikes. Among the different holding solutions, salicylic acid 150ppm + 10ppm nano silver + 4% sucrose exhibited the longest vase life (13.65 days). Results of this experiment confirmed that holding treatments exhibited better results compared to pulsing treatments in increasing the vase life of cut gladiolus spikes.ThesisItem Open Access Characterization of some upland rice (Oryza sativa L.) genotypes under low phosphorus condition(AAU, Jorhat, 2018-07) Shyam, Akash; Das, RanjanThe investigation was carried out for characterization of some upland rice (Oryza sativa L.) genotypes under low phosphorus condition during Jan 2017 to May 2018 in the Stress Physiology Laboratory, Department of Crop Physiology, Assam Agricultural University, Jorhat-13. The main objective of the investigation was to evaluate upland rice cultivars adapted under to low phosphorus condition and to identify the physiological traits contributing to rice growth and development under low phosphorus condition. The study was done to understand the mechanism of phosphorus altering the physiology of rice crop, and its relationship between yield, physiological attributes and nutrient status of rice as influenced by Phosphorus. In first experiment, fifty rice accessions of different genetic backgrounds were used for the evaluation of low-P tolerance. The accessions were grown in two sets of plastic pots; oneset was treated with – P and another with +P using Hoagland solution. Treatment was imposed at 5 days interval. The potential accessions were screened out under the above simulated level of P for studying tolerant ability of the lines using SES scoring. On the basis of SES scoring eight line viz. Kasalth, Ronga Ahu, Amo Amkel, Maipholong, Sesapal, Bizary, Bijor and Haringajali were identified as tolerant to low P.We made an attempt to study, the mechanism of tolerance to low P which was elucidated in second experiment. In the second experiment, the seed of screened lines were grown in the three sets of plastic pot, maintaining the soil with zero “0” level of P (normal soil), second at 10kg/ha of P (moderate dose) and third was maintained at 20kg ha-1 (recommended doses of P). Results obtained during the investigation revealed that P significantly influenced various morpho-physiological, biochemical and yield parameters.A significantly variable response was observed in genotypes due to different levels of P. Due to low P, stress induced reductionin terms of root length, root biomass, shoot dry weight, plant height, specific leaf weight, number of tillers per hill, no. of leaves per hill, and photosynthetic parameters were lower in Maipholong and at par with Kasalath (check line). However, Ronga Ahu and Amo Amkel also showed the similar trend compared to check line under low level of P. A reduction in values of relative membrane stability index and Chlorophyll Stability Index, proline content were recorded under „0‟ dose of P. Under low and moderate P level, a comparatively better performance was recorded in Maipholong and Kasalath in terms of yield and yield related parameter viz. panicle length, number of filled grain and grain yield. The tolerance indices parameter viz. P use efficiency and P uptake revealed that cultivar Maipholong and Kasalath showed maximum in all doses of P followed by Ronga Ahu and Amo Amkel. The susceptible lines invariably reflected less favourable plant P utilization, more metabolic de-arrangements in terms of photosynthesis rate, nitrate reductase activity and depression level of membrane stability. From the results of the experiment it might be concluded that Maipholong and Kasalath was more suitable under low P condition indicating that lines are adaptable to low phosphorus by maintaining better root growth, photosynthesis, chlorophyll stability index, NR activity and NPK level within the plant.
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