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ThesisItem Open Access PHYSIOLOGICAL BASIS OF ALUMINIUM TOLERANCE IN RICE (ORYZA SATIVA L.)(AAU, Jorhat, 2019-07) Faqiha, Ph.; Das, RanjanThe investigation was carried out to evaluate the performance of some rice (Oryza sativa L.) genotypes under different levels ofaluminium during November 2017 to December 2018 in the Stress Physiology Laboratory, Department of Crop Physiology, Assam Agricultural University, Jorhat-13. In first experiment, 149 rice genotypes collected from different North-Eastern States were screened for aluminium tolerancewith two different aluminium levels of 60 μM Al and 100 μM Al using Yoshida solution along with a control. Out of 149 genotypes, seven genotypes viz., Alubari Dhan, Dewri, Ayangleima, Marin Chatpi, Rene Nepung Aam, Rongabetguti and Rajamani were found to be promising in terms of Al tolerance and these were further evaluated in second experiment for mechanism of responses of Al. In the second experiment the screened rice genotypes were grown in potsin three different levels of Alviz.,100 μM Al (T1), 200 μM Al (T2), and 300 μM Al (T3) along with a control (T0) to study the mechanism of the morpho-physiological and biochemical traits contributing to rice growth and development under higher levels of aluminium. Results obtained during the investigation revealed that higher levels of Al significantly influenced on number of leaves, specific leaf weight, leaf area index, membrane stability index, total leaf chlorophyll content, in-vivo leaf nitrate reductase activity, SOD, root volume, root length, root dry weight, plant height and yield attributes in all the genotypes. However, among the seven genotypes Rajamani and Rene Nepung Aam showed less reduction in root length, photosynthetis rate and total chlorophyll. These two genotypes also showed the lowest per cent reduction in grain yield and yield attributesover control. This could be correlated with the increase in superoxide dismutase and proline content in the leaf with proportional decrement of MDA. The genotype Rajamani and Rene Nepung Aam accumulated less amount of aluminium in its root biomass as compared to other genotypes which indicates that this genotype has a better tolerance mechanism by excluding aluminium from the root system thereby contributing better growth and development. Considering the studied morpho-physiological, biochemical and yield related attributes, Rajamani and Rene Nepung Aam genotypes may be considered as the most promising genotypes among all seven genotypes under higher levels of Al in the present investigation.ThesisItem Open Access TOLERANCE OF SUMMER GREENGRAM GENOTYPES AGAINST WATER-LOGGING CONDITION(AAU, Jorhat, 2019-07) Saikia, Bhaskar; Kalita, PrakashA study was carried out in the Department of Crop Physiology and Stress Physiology premises, F.A., Assam Agricultural University to evaluate the physiological performance of some greengram genotypes as influenced by waterlogging condition of varying duration imposed at different stages of growth. Initially, a total of forty genotypes of greengram were evaluated for their ability to germinate and seedling growth under simulated waterlogged situation in petri-plates. Out of these genotypes, five were selected for further evaluation; they are NVL-855, KM 2355, AKM 12-28, Pratap and Sadiya Local. These five genotypes were further evaluated for their germination, seedling growth and final yield by growing them in pots filled with soil and FYM where inorganic nutrients were also supplied as per recommendation for greengram. The pots were kept under natural condition. Waterlogging conditions were created in the pots for specified length of time at vegetative and reproductive stages of the crop. When the waterlogging condition was imposed during vegetative and reproductive stage, the growth and development of the genotypes were found to be affected adversely. Longer the period of waterlogging, more severe was the affect on growth and development of the plant. Genotypes were found to show similar response to the waterlogging when plants were exposed to waterlogging at vegetative as well as reproductive stage. However, the impact of waterlogging introduced at reproductive stage was found to be more severe on the yield. The values for the traits namely leaf chlorophyll, leaf area, plant height, nitrate reductase activity, seeds/pod, pods/plant, root length, number of root nodules/plant, test weight, total biomass of the plant and harvest index were found to decline under waterlogged condition. Whereas, lipid peroxidase and superoxide dismutase activity showed higher values under waterlogged condition. The performance of the genotype namely Sadiya Local was found to be the best from the point of view of seed yield as influenced by waterlogging. The better performance of this genotype appeared to be related to higher values for the traits namely germination percentage, leaf chlorophyll, nitrate reductase activity, superoxide dismutase activity, number of pods/plant and harvest index. The genotype Sadiya Local showed a decline of 29.82% only in terms of seed yield/plant when the plants were exposed to 12 days of waterlogging at vegetative stage and 38.59% when exposed to 12 days of waterlogging at reproductive stage. The harvest index value were lowered by 12.5% and 20.87% under the waterlogging stress introduced at the vegetative and reproductive stages respectively. The results of the present study revealed that waterlogging has detrimental effects on the growth of summer greengram at all stages of crop growth. But the effects of waterlogging was more detrimental when imposed at reproductive stage compared to early seedling stage, since, it was found to result in a reduction of the harvest index by 28-30% in comparison to12-15% that resulted from waterlogging stress imposed at early vegetative stage. Among the five genotypes studied, Sadiya Local and AKM 12-28 can be considered to be tolerant ones to waterlogging followed by Pratap.ThesisItem Open Access PHYSIOLOGICAL EFFECT OF HIGH TEMPERATURE STRESS ON SOME SALI RICE GENOTYPES(AAU, Jorhat, 2019-07) SAIKIA, KABITA; . Dey, P.CPlants are sensitive to high temperature during critical stages such as flowering and seed development. With the increase in daily maximum temperature averaged over flowering period above about 360C, rice yield generally declined because of spikelet sterility induced by high temperatures. Rice crop exposure to the spells of high temperature results in grain yield diminish due to spikelet sterility, reduction in source and sink activities, assimilate partitioning. Identifying genotypic variation through field screening for high temperature tolerance is required for initiating successful breeding programme to develop rice cultivars capable of higher yields under projected climatic change conditions. In view of the importance of high temperature tolerance in rice, an experiment was carried out to study “Physiological effect of high temperature stress on some sali rice genotypes” during kharif, 2017 at Regional Agricultural Research Station, AAU, Titabar in split-plot design with conditions (control and high temperature) as main-plot treatment and 33 rice genotypes as sub-plot treatment including N22 as heat tolerant check variety. Heat stress was imposed in the field immediately after PI stage by enclosing the field grown crop with a make shift locally fabricated polythene tent (<92% transmittance), duly supported by bomboo sticks. The polythene cover was removed at the time of harvest. Enclosing the field crop during reproductive phase with polythene sheet had resulted in significant increase in maximum temperature. Another set of same varieties was grown in ambient condition. The increase in maximum temperature was 1-3.50C over the ambient temperature and minimum temperature had increased by 0.5-1.50C. Elevated temperature had no significant effect on mean days to flowering and days to maturity for all the genotypes. However, significant differences were observed between varieties. Among the genotypes IET 26774, IET 26776, IET 26778, 175-2K, S-458, N22 were less affected in morphological traits under high temperature stress. The number of filled grains per panicle is an important yield determining character which was significantly affected by high temperature stress. The sterility percentage were minimum (2-7%) for 175-2K, S-458, IET 26778 due to heat stress. Yield attributes such as panicle weight, harvest index, test weight, panicle number m-2, grain number panicle-1, spikelet number panicle-1 and grain yield were significantly reduced under high temperature stress. Dry matter heat susceptibility index (DMHSI) varied between a minimum of 6.76 (N22) to a maximum of 41.52 (IET 26777). IET 26757, IET 26759, IET 26760, IET 26778, IET 26776, 175-2K, S-458 and N22 are the entries with DMHSI value <15 indicating relative tolerance to heat stress. The grain yield heat susceptibility index (GYHSI) was lowest 11.24 in 175-2K. Amongst the remaining varieties IET 26757, IET 26778, S-458 and N22 performed relatively better with < 15 GYHSI. Exposure to high temperature caused marked reduction in 1000 grain weight. The interaction between genotypes and treatment was found to be highly significant. Minimum reduction in test wt. were observed in IET 26776, 175-2K and S-458 (between 7-9% ) which were less than the check var. N22 (11%). The values for the traits namely leaf chlorophyll, starch content, nitrate reductase activity were found to decline under high temperature stress condition. Whereas, nitrogen content in leaf showed higher values under high temperature stress condition.The desirable traits of maintenance of low profile of the pace of reduction of chlorophyll content, starch content, NR acivity, leaf N content of the varieties viz. IET 26766, IET 26771, IET 26774, IET 26775, 175-2K, S-458 and N22 during high temperature stress condition. The varieties 175-2K, S-458, IET 26778 reflected the inherent capabilities to tolerate high temperature stress with less reduction in grain yield and yield components, grain sterility percentage and other biochemical parameters, could be used as a donor in various breeding programmes also could be adopted in farmer’s field to increase the economic yield.ThesisItem Open Access Effects of some Organic Nutrients on Physiology of Scented Rice (Oryza sativa L.)(AAU, Jorhat, 2019-07) HAZARIKA, STUTIPRIYA; Medhi, Ajay KumarRice is widely grown as staple food for half of the world’s population. In the post independence period, the most important challenge in India has been to produce enough food for the growing population.Hence, high yielding varieties are being used with infusion of irrigation water, fertilizers, or pesticides.This combination of high yielding production technology has helped the country develop a food surplus as well as contributing to concerns of soil health, environmental pollution, pesticide toxicity,and sustainibility of agricultural production. Scientist and policy planners are, therefore reassessing agricultural practices which relied more on biological inputs rather than heavy usage of chemical fertilizers and pesticides.Organic farming can provide quality food without adversely affecting the soil health and environment. India has tremendous potential to become a major exporter of organic rice in the international market. Assam is also known to be the centres of its origin along with wide range of rice cultivars. Among all cultivars, aromatic rice, more particularly joha group of this region enjoys the top position. The joha rice is known for its unique aroma, superfine kernel, good cooking qualities and excellent palatability. It is now established that organic farming can improve the quality of scented rice. Assam can earn good revenue by promoting joha rice to the national and global markets asit fetches high premium price for its high standard quality traits .The information about the effects of the organic inputs on scented rice is very limited in Assam. Considering the importance of organic farming and to generate comprehensive scientific research data, the present investigation was conducted. The study was carried out on growth physiology, nutrients uptake pattern. Yield and quality parameters under the influence of organic nutrient scented on scented joha rice under Assam condition. The eight treatment combinations of organic inputs were laid out in RBD with 3 replications. Organic nutrients combination were taken as treatment such as T1. Enrich compost (5 t/ha) + Biofertilizer consortium as root dip (4kg/ha seedling), T2 .Green manure (2.5 t/ha) +azolla( 20kg/ha) + Biofertilizer consortium( 4kg/ha seedling) as root dip + Rock phosphate (17 kg/ha), T3. Green manure(5t/ha)+Azolla(20kg/ha) +Biofertilizer consortium (4 kg/ha seedling) as root dip + Rock phosphate (17 kg/ha), T4. Vermicompost (2.5t/ha )+ Azolla( 20 kg/ha) +Biofertiliser consortium as root dip (4kg/ha seedling) +rock phosphate( 17 kg/ha), T5. Vermicompost(5t/ha)+ Azolla (20kg/ha)+Biofertilizer consortium( 4 kg/ha seedling) as root dip +rock phosphate(17 kg/ha), T6. Green manure (2.5t/ha)+ Vermicompost( 2.5t/ha)+Consortium(4kg/ha seedling) as root dip 4+Rock phosphate (17kg/ha)+Azolla( 20 kg/ha), T7. Vermicompost( 2.5t/ha)+ Neem cake (300kg/ha)+Half basal and half top dressed +Biofertilizer consortium(4kg/ha seedling ) as root dip and T8. Control. The experiment was conducted at organic block of Regional Agricultural Research Station (RARS) in the kharif season of 2017 and 2018. The organic inputs under study was produced under strict organic guidelines of Assam Agricultural University, Jorhat. The seeds of Keteki joha was collected from organic block of RARS, Titabar, Assam. The plant protection measures also carried out by organic standards. In the control plot, no external organic inputs were added, may be treated as organic with native fertility and biological make up. Seed treatment will be carried out by soaking the seeds 12 hours in a solution of pseudomonas flouroscense @ 10 g/litre of water/kg of seed. For both the years, dhaincha as green manure crops was grown using 50 kg ha-1 in the month of May in separate plot till 60 days. After harvesting, it was weighed, chopped and incorporated as per treatments one week before transplanting of rice. Enriched composed was prepared by taking ordinary compost prime with microbial consortia @ 1%, mixed with 1% rock phosphate (17 kg per 100 kg compost and cure for 15-20 days. Enriched compost, vermicompost was applied one week before transplanting of rice . Before transplanting root dip treatment was carried out with bio fertilizer Consortium @ 10 g/kg of seed. Consortium is a specific formulation of Azospirillum, Azotobacter, Phosphorus solubilizing bacteria (PSB) and Rhizobium. Azolla was applied 7 days after transplanting of rice as per the treatment. After formation of a thick mat, the azolla was incorporated with soil. The results revealed that application of different treatment significantly increased the plant height, tiller number hill-1, flag leaf area in treatment T6. The highest value recorded in case of the plant height , tiller no hill-1, flag leaf area in the treatment T6 were 78.5 cm, 12.1, 35.33 cm2. The different growth parameters significantly recorded highest CGR of (24.0 g/m2/day), RGR of (61.39 g/g/day), SLW of (8.56 g/dm2) , NAR of (48.4 mg/cm2/day) , LAI of (4.32), dry matter partitioning of (1320.06 g m-2) at treatment T6. The biochemical parameters chlorophyll content (3.12 mg/g/f.wt) and nitrate reductase activity (2.80 u mole N02 - formed g-1 f.w.hr-1) which were significantly higher over all other organic inputs . The quality parameters TSP ( 8.13% ) ,Starch ( 64.6%) ,TSS (0.95%) increased significantly in treatment T6. The Nitrogen (54.05 kg/ha), Phosphorus (6.77 kg/ha) , Potassium (99.05 kg/ha) uptake by the plant were significantly increased in treatment T6 compared to control. Application of T6.exhibited the highest grain yield and yield attributing characters such as panicle m2, 1000 grain weight, grain per panicle over all other organic inputs applied. The highest yield of (38.05 q/ha) and yield attributing characters panicle m2 of (304.3 m2), grain/ panicle of (84.43 ) and 1000 grain weight of (23.62 g) were recorded in treatment T6. The highest straw yield were recorded in the T7 (73.97 q/ha) and the highest harvest index of (33.60 q/ha ) were recorded in the treatment T6. Though the cost of cultivation was highest in treatment T1.due to high value of enriched compost and among different organic inputs, High benefit cost ratio was found to be highest in treatment T6.