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Dr. Rajendra Prasad Central Agricultural University, Pusa
In the imperial Gazetteer of India 1878, Pusa was recorded as a government estate of about 1350 acres in Darbhanba. It was acquired by East India Company for running a stud farm to supply better breed of horses mainly for the army. Frequent incidence of glanders disease (swelling of glands), mostly affecting the valuable imported bloodstock made the civil veterinary department to shift the entire stock out of Pusa. A British tobacco concern Beg Sutherland & co. got the estate on lease but it also left in 1897 abandoning the government estate of Pusa.
Lord Mayo, The Viceroy and Governor General, had been repeatedly trying to get through his proposal for setting up a directorate general of Agriculture that would take care of the soil and its productivity, formulate newer techniques of cultivation, improve the quality of seeds and livestock and also arrange for imparting agricultural education. The government of India had invited a British expert. Dr. J. A. Voelcker who had submitted as report on the development of Indian agriculture. As a follow-up action, three experts in different fields were appointed for the first time during 1885 to 1895 namely, agricultural chemist (Dr. J. W. Leafer), cryptogamic botanist (Dr. R. A. Butler) and entomologist (Dr. H. Maxwell Lefroy) with headquarters at Dehradun (U.P.) in the forest Research Institute complex.
Surprisingly, until now Pusa, which was destined to become the centre of agricultural revolution in the country, was lying as before an abandoned government estate. In 1898. Lord Curzon took over as the viceroy. A widely traveled person and an administrator, he salvaged out the earlier proposal and got London’s approval for the appointment of the inspector General of Agriculture to which the first incumbent Mr. J. Mollison (Dy. Director of Agriculture, Bombay) joined in 1901 with headquarters at Nagpur
The then government of Bengal had mooted in 1902 a proposal to the centre for setting up a model cattle farm for improving the dilapidated condition of the livestock at Pusa estate where plenty of land, water and feed would be available, and with Mr. Mollison’s support this was accepted in principle. Around Pusa, there were many British planters and also an indigo research centre Dalsing Sarai (near Pusa). Mr. Mollison’s visits to this mini British kingdom and his strong recommendations. In favour of Pusa as the most ideal place for the Bengal government project obviously caught the attention for the viceroy.
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ThesisItem Open Access Effect of flooding and chemical oxygen enrichment on physiology of Mungbean [Vigna radiata (L.) Wilczek](Dr. Rajendra Prasad Central Agricultural University, Pusa, Samastipur (Bihar), 2019) Reddy, Desam Abhinay; Kumar, ShaileshFlooding is a serious problem which affects growth and yield in various crops and flooding events are expected to increase globally as a result of climate change. Mungbean highly sensitive to waterlogging, particularly during the early stages of growth. Waterlogging during early growth stages, cause considerable yield losses in mungbean. The main cause of damage under waterlogging is oxygen deficiency, lack of oxygen shifts the energy metabolism from aerobic mode to anaerobic mode, causes oxidative stress, interruption of nutrient and water intake. Chemical oxygen fertilization of the root zone with addition of fast release (liquid) formulations such as hydrogen peroxide, is a potential method of alleviating root hypoxia. Hydrogen peroxide decomposes in the soil releasing which is needed for aerobic metabolism in the roots. The purposes of this study is to examine and explore the possible effect of application of H2O2 (as a source of oxygen) in flooded soil in improving growth and yield of mungbean genotypes under flooding stress conditions and for better understanding of mechanism, changes in physiological attributes and biochemical traits were also studied. The present investigation entitled “EFFECT OF FLOODING AND CHEMICAL OXYGEN ENRICHMENT ON PHYSIOLOGY OF MUNGBEAN [Vigna radiata (L.) Wilczek]” was conducted with two objectives (1) Identification of a contrasting set of mungbean genotypes for flooding stress on the basis of morpho-physiological traits. (2) To investigate the response of exogenous application of hydrogen peroxide on tolerance mechanism of mungbean genotypes under flooding stress. Complete experiment was performed in pot and morphological, physiological and biochemical parameters were studied in 21-days-old mungbean genotypes. Effect on yield and yield attributes were also studied in in all treatments. For identification of contrasting sets of mungbean genotypes to flooding stress, pot culture experiment was performed with sixteen mungbean genotypes. All genotypes were subjected to flooding stress for 7 days and morpho-physiological data was collected at the end of flooding stress. The morphological and physiological parameters were significantly decreased under flooding stress compared to control condition. Among genotypes, least percent reduction in shoot length, root length, plant height, dry weight, relative water content and SPAD value was observed in genotypes IPM-02-3 and GAM-5 and maximum percent reduction was observed in PANT M-5 and SML-1901. In objective second, two experiments were conducted. First experiment was performed with four mungbean genotypes, IPM-02-3, GAM-5 (tolerant genotypes) and PANT M-5, SML-1901 (susceptible genotypes) to identify optimum H2O2 concentration. Total three concentrations (1%, 2% & 3%) of H2O2 was used as a source of oxygen. Addition of hydrogen peroxide in flooded soil helped in maintaining the higher growth and physiological traits compared to untreated condition. Among three different concentrations, 3% hydrogen peroxide showed better results in all growth and physiological parameters than 1% & 2% concentrations of hydrogen peroxides under flooding stress. Second experiment was also performed in pot with one tolerant (IPM-02-3) and one susceptible genotype (PANT M-5), to compare the change in morphological, physiological traits, biochemical traits, yield and yield attributes of mungbean genotypes under control, flooding stress and addition of 3% hydrogen peroxide in flooded soil. Results showed that flooding stress significantly decreased the growth parameters (plant height, no of nodules and dry weight), physiological parameters (RWC, chlorophyll and carotenoid contents, SPAD value, and MSI), and yield and yield attributes (yield per plant, test weight, number of pods plant-1, and number of seeds plant-1) in both mungbean genotypes compared to control. However, biochemical traits (TBARS content, alcohol dehydrogenase, catalase, peroxidase and SOD activity, and proline contents) increased significantly compared to control plant. Addition of 3% hydrogen peroxide in flooded soil facilitated to maintain higher growth (plant height, no of nodules and dry weight), physiological parameters (RWC, chlorophyll and carotenoid contents, SPAD value, and MSI), and yield and yield attributes (yield per plant, test weight, number of pods plant-1, and number of seeds plant-1) in both mungbean genotypes compared to untreated flooded condition. The biochemical parameters (TBARS content, alcohol dehydrogenase, catalase, peroxidase and SOD activity, and proline contents) were decreased significantly compared to untreated flooded condition as stress level decreased which was reflected in terms of decrease in TBARS contents. Overall flooding stress at vegetative stress adversely affected the mungbean genotypes and genotypic variation in response to flooding stress was observed. The addition of 3% hydrogen peroxide in flooded soil mitigated the adverse effect on growth and yield of mungbean genotypes. Thus, the potential exists to use chemical oxygen fertilization to reduce the adverse effect of flooding stress in flood-prone areas and in flooding sensitive genotypes. However, further studies are needed for different soil types and in field conditions.ThesisItem Open Access Role of hydrogen peroxide in salinity tolerance of Mungbean [Vignaradiata (L.) Wilczek](Dr. Rajendra Prasad Central Agricultural University, Pusa, Samastipur (Bihar), 2019) Ranjan, Deepika; Kumar, ShalieshSalinity is one of the most atrocious environmental factors limiting the productivity of crop plants because most of the crop plants are sensitive to salinity caused by high concentrations of salts in the soil. Mungbean is an economically important food grain legume crop, which is highly sensitive to salinity stress. It is established that hydrogen peroxide (H2O2), is toxic at high levels and causes oxidative damage but could also act as a signaling molecule at low concentrations leading to development of adaptive mechanisms in plants under stressful conditions. The present study entitled, “Role of hydrogen peroxide in salinity tolerance of mungbean [Vigna radiata (L.) Wilczek]” was conducted with two objectives, (1) To assess the effect of pre-seed soaking treatment of hydrogen peroxide at different concentrations on morpho-physiological traits of tolerant and susceptible mungbean genotypes under salinity stress. (2) To investigate the response of pre-seed soaking treatment of optimum concentrations of hydrogen peroxide on tolerance mechanism of mungbean seedlings under salinity stress. The morpho-physiological and biochemical parameters were estimated in 12-day-old seedlings of two mungbean genotypes i.e., TMB-37 (tolerant) and MH-1314 (susceptible) grown in normal and saline soil in pot condition. The yield and yield attributing traits as well as dry matter partitioning were also estimated in all treatments and conditions of both the genotypes. Salinity stress significantly decreased the seedling emergence and morphophysiological parameters (shoot length, root length, plant height, seedling dry weight, SPAD value, RWC, chlorophyll contents, CSI and MSI) in both the genotypes. However, reduction per cent was comparatively higher in susceptible genotype (MH- 1314) as compared to tolerant genotype (TMB-37). Seed priming with lower concentration of hydrogen peroxide (0.01%, 0.03% and 0.05% H2O2) increased seedling emergence and morpho-physiological parameters (shoot length, root length, plant height, seedling dry weight, SPAD value, RWC, chlorophyll contents, CSI and MSI) in both the genotypes and under normal and salinity stress condition. However, maximum increase was observed in treatment (0.01% H2O2). Priming with higher concentrations (0.5% and 1.0% H2O2) decreased the seedling emergence and morphophysiological traits in both genotypes under normal and salinity stress condition. Salinity stress significantly increased the lipid peroxidation in leaf and root of both tolerant as well as susceptible mungbean genotypes as compared to the normal condition. The treatment with hydrogen peroxide (0.01%) significantly reduced the lipid peroxidation in leaf and root of both tolerant (TMB-37) and susceptible (MH- 1314) genotypes under normal and salinity stress conditions. The antioxidant enzyme activity (CAT, SOD and POX) and proline content were significantly higher in leaf and root in both tolerant and susceptible mungbean genotypes under salinity stress condition with respect to the normal condition. The treatment with hydrogen peroxide (0.01%) further increased the CAT, SOD and POX activity and proline content in leaf and root of both tolerant (TMB-37) and susceptible (MH-1314) genotypes under both normal and salinity stress conditions. Salinity stress also significantly decreased yield per plant, yield attributing components and dry matter accumulation in both the genotypes. However, priming with optimum concentration (0.01%) of hydrogen peroxide increased the seed yield per plant, yield attributing components (number of seeds per pod, number of pods per plant and number of pods per cluster) and dry matter accumulation (pod, leaf, shoot and root) in both mungbean genotypes under normal and salinity stress conditions. Overall, the data show that hydrogen peroxide increased the seedling emergence per cent, as well as the morpho-physiological traits in a concentrationdependent manner. Lower concentration of H2O2(0.01%) alleviated the salinity stress, by increasing the antioxidant enzyme activity, proline level and specific leaf area appeared to be the key factor for efficient growth and yield responses under salinity stress condition. This suggests that H2O2 could be used as potential molecules to improve seedling emergence, growth and yield under salt stress.ThesisItem Open Access Physiological response of lentil (Lens culinaris Medik.) genotypes to salinity stress and its mitigation through microbial inoculation(Dr. Rajendra Prasad Central Agricultural University, Pusa, Samastipur (Bihar), 2018) Rani, Ediga Usha; KavitaLentil is an important legume crop which is highly sensitive to salinity and is adversely affected by salt stress in terms of growth and yield. Inoculation of plants with microbes such as Trichoderma viride, Bacillus, and Pseudomonas can enhance plant growth during salt stress, which is an eco-friendly approach to sustainable agriculture. The present investigation entitled “Physiological response of lentil (Lens culinaris Medik.) genotypes to salinity stress and its mitigation through microbial inoculation” was conducted with two objectives viz., to identify contrasting sets of lentil genotypes against salinity stress on the basis of physiological traits, and to study physiological response of microbes application in contrasting genotypes under salinity stress. For the identification of contrasting sets of lentil genotypes to salinity stress, experiment was performed in Petri dishes with seventeen genotypes. All genotypes were subjected to control and salinity stress (4.0 and 8.0 dSm-1) for 7 days and physiological parameters viz. germination percentage, seedling length, seedling dry weight, germination relative index, vigour index-І and vigour index-II were observed. Results showed a significant decrease in values of these parameters under salinity stress compared to control condition. Among genotypes, the least reduction in germination percentage, seedling length, seedling dry weight, germination relative index, vigour index-І and vigour index-II value were observed in genotypes RLG-234 and RLG-254 while the maximum percent reduction was observed in LL-931 and SJL 7-2. For the second objective, contrasting set of genotypes i.e., tolerant (RLG-234 and RLG-254) and susceptible genotypes (LL-931 and SJL 7-2) were sown in CRD with three replications in plastic pot filled with soil having EC 4.0 dSm-1. The contrasting genotypes were primed with different commercial formulation of microbes (Trichoderma viride, Pseudomonas fluorescence, Bacillus subtilis, Trichoderma viride + Pseudomonas fluorescence, Trichoderma viride + Bacillus subtilis, Pseudomonas fluorescence + Bacillus subtilis and Trichoderma viride + Pseudomonas fluorescence + Bacillus subtilis) and morpho-physiological and biochemical response under salinity stress was studied. Results showed that morphological (root length, shoot length, root dry weight, shoot dry weight) , physiological (relative water content, membrane stability index, total chlorophyll content) biochemical (proline, soluble protein, total free amino acids) and antioxidant enzymes (catalase, peroxidase, superoxide dismutase) were significantly increased in all the treatments over control (without microbial inoculation), whereas lipid peroxidation and protease activity was significantly decreased in all the treatments. Sodium content was decreased while potassium content was significantly increased in both root and shoot. Potassium- sodium ratio was higher in shoot than in root. On the basis of present study it was concluded that, salinity stress adversely affected morpho-physiological, biochemical attributes and nutritional content (Na and K) in lentil genotypes. These parameters were improved under salinity stress with the combined application of Pseudomonas fluorescence, Bacillus subtilis and Trichoderma viride showing synergistic response in ameliorating salinity stress.ThesisItem Open Access Physiology of mustard (Brassica juncea L. Czern and Coss) genotypes under salinity and high temperature stress at seedling stage(Dr. Rajendra Prasad Central Agricultural University, Pusa, Samastipur (Bihar), 2018) Prasad, Satya Narayan; KavitaRapeseed-mustard is considered to be the second largest edible oilseed crop in the world after soybean. However, this is sensitive to salinity stress that adversely affects growth and yield. The crop also faces high temperature at seedling stage when sown late. The present investigation was carried out to screen mustard genotypes against salinity and high temperature stress conditions and to study physio-biochemical response in two contrasting genotypes under salinity and high temperature stress condition at seedling stage. The salt solution was prepared by using NaCl: CaCl2 in the ratio of 7:2 (w/v) and its electrical conductivity of different salinity levels (4.0 dSm-1 and 6.0 dSm-1) were maintained by direct reading conductivity meter. Twenty one genotypes viz., CS-52, CS-56, CS2002-61, CS2002-189, CS2002-195, CS2004-105, CS2004-106, CS2004-114, CS2004-191, CS2005-124, CS2005-125, CS2009-105, CS2009-145, CS2009-256, CS2009-261, CS2009-332, CS2009-347, CS2013-10, CS2013-19, CS2013-27 and CS1013-41 were subjected to primary screening at different stresses sown in seedling trays filled with soil. The treatments comprised of (a) Control (1.2 dSm-1) (b) 1.2 dSm-1 + High temperature (40℃) (c) Salinity of EC = 4.0 dSm-1 (d) Salinity of EC = 6.0 dSm-1 (e) Salinity (EC = 4.0 dSm-1) + high temperature (40℃) (f) Salinity (EC = 6.0 dSm-1) + high temperature (40℃) that were compared with control (1.2 dSm-1). The contrasting set of genotypes identified were used to study the physio-biochemical changes in 15-day old seedlings. On the basis of physiological parameters viz., survival percent, seedling length, dry weight of seedlings, vigour index-I and vigour index-II of contrasting set of genotypes were identified. Survival percent, seedling length, dry weight of seedlings, vigour index-I and vigour index-II declined in all the genotypes in different treatments over control, however, the decline was less in genotypes CS2009-347 and CS-52 whereas it was more in CS2009-256 and CS2009-145. The genotypes CS2009-347 and CS-52 were identified as relatively tolerant, whereas CS2009-256 and CS2009-145 were found to be susceptible genotypes. Stress application resulted in decline in membrane stability index, relative water content, chlorophyll content and soluble protein content; however, the decline was less in tolerant genotypes. Contrary to this, carotenoids content, proline content, catalase activity, peroxidase activity were found to increase, the increase being more pronounced in tolerant genotypes. Total free amino acids and protease activity also enhanced with the percent enhancement being more in susceptible genotypes. Results of this study will be helpful for finding salinity and high temperature tolerant genotypes for mustard improvement programme.ThesisItem Open Access Physiology of wheat (Triticum aestivum L.) under salt and high temperature stress condition(Dr. Rajendra Prasad Central Agricultural University, Pusa, Samastipur (Bihar), 2018) Neelambari; Singh, Ajay KumarUnder natural conditions, plants are often subjected to a combination of different stresses such as salt stress and heat shock. Wheat crops are slightly salinity tolerant but as a cool season crop it is sensitive to heat stress at both vegetative and reproductive stages. Recent studies revealed that the response of plants to a combination of two different stresses is specific and cannot be deduced from the stresses applied individually because increased transpiration rate associated with high temperature stress worsen the harmful effects of salinity stress. Therefore, the present investigation entitled “Physiology of wheat (Triticum aestivum L.) under salt and high temperature stress condition” was conducted with three main objectives (1) Screening of wheat genotypes for combined salt and high temperature stress to identify the contrasting sets of wheat genotypes on the basis of physiological traits. (2) To study physiological and biochemical mechanisms of tolerance of wheat genotypes subjected to independent, and combined salt and high temperature stress conditions. (3) To quantify the changes in yield and yield attributes of wheat genotypes grown under independent, and combined salt and high temperature stress conditions. In the present study, two independent experiments were conducted. The first experiment was done in laboratory condition where 46 wheat genotypes were screened for individual and combined salinity and high temperature stress condition at seedling stage. Wheat seeds were sown in petri plate in three replications for germination. A saline solution of composition NaCl:CaCl2: Na2SO4 (7:2:1) with salinity levels at 4.0 and 8.0 dS m-1 were used as irrigation solution for giving salt stress treatments. High temperature treatment, was given by keeping the petri dishes in incubator at temperature 37 ± 2°C, and combined salinity and high temperature stress was given by transferring salinity stressed plant to incubator at high temperature (37 ± 2°C). The physiological parameters were measured in 10-day-old seedling. Physiological parameters (germination percentage, shoot length, seedling length, shoot fresh weight, root fresh weight, seedling fresh weight, root dry weight, shoot dry weight, seedling dry weight, vigour index I, vigour Index II and SPAD value) were measured and found to be reduced, except root length which was found to be increased in some genotypes and decreased in others under salinity, high temperature and combined stress. However the reduction was more pronounced under combined stress. On the basis of physiological data, the contrasting set of wheat genotypes (tolerant genotypes, i.e., KRL-1-4, KRL-19 and HD-2733, and susceptible genotypes, i.e., HT-8, HI-1563 and HD-2987) were identified for further study. The genotypes identified from screening experiment were used for a pot culture experiment to study the physiological and biochemical mechanism of stress tolerance and yield/yield associated parameters. Three replications of pot were arranged in factorial completely randomized design. Four treatments were given, i.e., control (wheat genotypes were sown timely in soil with ECe 1.3 dS m-1), salinity stress treatment (wheat genotypes were sown timely in natural saline soil with ECe 7.4 dS m-1), high temperature stress treatment (wheat genotypes were sown late in soil with ECe 1.3 dS m-1) and combined salinity and high temperature stress treatment (wheat genotypes were sown late in natural saline soil with ECe 7.4 dS m-1). The physiological and biochemical parameters were measured in flag leaf at anthesis period and yield parameters were measured at physiological maturity. The result revealed a decrease in physiological parameters in all wheat genotypes, while in tolerant group the decrease was less in all parameters, i.e., relative water content (25.0-29.6%), membrane stability index (23.9-27.2%), total chlorophyll (41.1-42.4%) and carotenoids content (14.9-17.2%), chlorophyll stability index (30.8-36.2%) and SPAD value (26.1-28.7%) as compared to susceptible group of genotypes in which percentage change in relative water content ranged from 37.7 to 41.2%, membrane stability index (37.9-44.5%), total chlorophyll (52.6-60.2%) and carotenoids content (15.1-33.9%), chlorophyll stability index (44.6-49.9%) and SPAD value (33.5-40.9%) under combined salinity and high temperature stress treatments. However, lipid peroxidation was increased in all the genotypes with minimum percentage increase in tolerant group which ranged from 58.6 to 60.3% and maximum percentage increase in susceptible group ranged from 71.4-88.3% under combined salinity and high temperature stress treatments. Greater antioxidant enzyme activities were induced in tolerant group, i.e., peroxidase (61.8-69.8%) and superoxide dismutase activity (75.4-86.9%). Similarly, proline content (61.1-68.1%), total phenol content (59.9-71.9%), total soluble sugar (42.5-48.9%), and free amino acids (43.3-50.9%) were higher in tolerant types, in comparison to susceptible group, i.e.,, peroxidase (40.6-49.2%), superoxide dismutase activity (50.7-56.3), total soluble protein (12.2-24.4%), proline content (37.6-47.4%), total phenol content (43.8-49.0%), and free amino acids (21.1-32.2%) under combined stress condition. However, total soluble protein content was found to be decreased less in tolerant group (19.6-21.6%) then in susceptible group (36.6-28.4%) under combined stress condition. Irrespective of the genotypes, combined stress reduced the yield and yield components in all genotypes. However, the reduction was minimum in tolerant genotypes, i.e., plant height (25.8-30.6%), number of grain per ear (28.6-34.1%), test weight (29.2-31.9%), harvest index (36.7-39.0%) and yield per plant (37.6-43.6%) as compared to susceptible genotypes in which reduction in plant height ranged from 36.9 to 49.6%, number of grain per ear 44.4 to 49.4%, test weight 38.7 to 43.4%, harvest index 47.3 to 50.3% and yield per plant 53.5 to 58.3% under combined stress treatments. However, floret sterility index was increased in all the genotypes with minimum percentage increase in tolerant group which ranged from 67.0-74.1% and maximum percentage increase in susceptible group ranged from 96.3 to 101.2% under combined salinity and high temperature stress treatments. From the present investigation it was evident that tolerant genotypes, i.e., KRL-19, KRL-1-4 and HD-2733 had the potential to cope up with the adverse effect of given stress treatments and they performed well under stress condition with least reduction in physiological, yield and yield associated parameters and greater increase in biochemical parameters. Among all parameters, antioxidants enzyme activity (SOD), phenol and proline content were highly correlated with yield per plant and showed maximum induction under combined salinity and high temperature stresses. Hence, the higher percentage increase in these parameters may be the reason for the tolerance of genotypes, HD-2733, KRL-19 and KRL-1-4. Possibly, some of these indices might prove useful for improving wheat genotypes to withstand combined salinity and high temperature.ThesisItem Open Access Physiological response of Mung bean [Vigna radiata L. (Wilczek)] genotypes to application of salicylic acid and trichoderma under salinity stress(Dr. Rajendra Prasad Central Agricultural University, Pusa, Samastipur (Bihar), 2018) Kumar, Suresh; KavitaThesisItem Open Access Physiology of mungbean [Vignaradiata(L.)Wilczek] under salt and high temperature stress condition(Dr. Rajendra Prasad Central Agricultural University, Pusa (Samastipur), 2018) Kumari, Shikha; Kumar, ShaileshMany agricultural lands affected by salinity, the influence of salt stressis aggravated by the simultaneous action of high temperature. Recent studies revealed that the response of plants to a combination of two different stresses is specific and cannot be deduced from the stresses applied individually. Here, we report on the respons1e of mungbean seedlings to individual and combination of salt and high temperature stress. The present study entitled “Physiology of mungbean [Vigna radiata (L.) Wilczek] under salt and high temperature stress condition” was conducted with three objectives (1) Screening of mungbean genotypes for combined salt and high temperature stress to identify contrasting sets of mungbean genotypes on the basis of physiological traits(2) To study physiological and biochemical mechanisms of tolerance of mungbean genotypes subjected to independent, and combined salt and high temperature stress condition.(3) To study the ionic and nutrient homeostasis in contrasting sets of mungbean genotypes subjected to independent, and combined salt and high temperature stress condition. Entirestudies were performed in 8 days old mungbean seedling grown in petriplate. For screening of contrasting sets of genotypes, experiments were performed with thirty one mungbean genotypes. Germination percentage and growth parameters (seedling dry weight, root length & seedling length, seedling vigour I & II, germination relative index) and physiological traits (chlorophyll contents measured in terms of SPAD units), were recorded in 8 days old mungbean seedling, and on the basis of growth performance under combined stress condition, two sets of contrasting mungbean genotypes were identified (TMB-37 & Pusa 1501, relatively tolerant for combined stressand MH-1314 & MH- 1315, relatively susceptible for combined stress). Second experiment was conducted to compare the changes occurred due individual and combined stress on physiological and biochemical traits.Results showed that combined stress severely reduced the photosynthetic pigment contents, carotenoids contents, SPAD value, chlorophyll stability, relative water contents, membrane stability compared to individual stress. Reduction was more in susceptible group compared to tolerant group of genotypes. In tolerant group the levels of antioxidant enzyme activity (peroxidase, CAT and SOD) and proline were higher compared to susceptible group both under individual and under combined stress conditions. Compared to individual stress the antioxidant enzyme activity (peroxidase, CAT and SOD) and proline were higher under combined stress conditions. Lipid peroxidation (estimated in terms of TBARS content) were also significantly high in combined stress compared to individual stress. In third experiments ionic and nutrient homeostasis estimated by analyzing the content of Na, K, and Zn and Fe in shoot and root of contrasting sets of mungbean genotypes subjected to independent, and combined salt and high temperature stress condition. Results indicated that tolerant genotypes maintained high K-Na ratio in both shoot and root compared to susceptible genotypes under individual and combined stress conditions and produced more dry matter compared to susceptible genotypes. Reduction in K-Na ratio both shoots and roots were more in combined stress compared to individual stress. Zn and Fe mobilization was severely affected under stress condition in all genotypes under individual and combined stress conditions, however tolerant genotypes able to maintain more Zn and Fe content in their shoot and root compared to susceptible genotypes. From Pearson Correlation Matrix it is clear that the endogenous seed Zn contents was positively correlated with dry weight, germination percentage, total chlorophyll, RWC, SPAD value, Fe & Zn content of shoot and root, and K-Na ratio. Therefore, seed Fe & Zn can also be used trait for screening of genotypes under individual & combined stress conditions during seedling stage.ThesisItem Open Access Studies on protective role of cytokinin in wheat (Triticum aestivum L.) under combined drought and high temperature stress condition(Dr. Rajendra Prasad Central Agricultural University, Pusa (Samastipur), 2017) Kumari, Sanam; Kumar, ShaileshDrought and high temperature stress often occur simultaneously especially in rainfed grown wheat crop causing severe yield loss in most of the wheat growing areas of the world. The simultaneous effects of these two stresses on crop performance in terms of growth, development, biomass accumulation, and yield may be quite different than the individual stress, but there are limited studies on this topic. Drought as well high temperature stress inhibits CK synthesis and accelerates CK degradation, reducing CK levels in roots and shoots. Increasing endogenous CK content through exogenous application of CK or genetic modification to overexpress isopentenyl transferase (ipt) controlling cytokinin synthesis has positive effects on improving plant tolerance to stress, which has been attributed to the promotion of photosynthesis, water use efficiency, and antioxidant metabolism of shoots in various plant species. CK have been shown to modulate leaf enzymatic antioxidant activities (i.e. POD and SOD), activating leaf defenses to abiotic stresses. CKs may retard senescence directly by scavenging or interfering with free radicals, which are proposed to be involved in this process. The present investigation entitled “Studies on protective role of cytokinin in wheat (Triticum aestivum L.) under combined drought and high temperature stress condition” was conducted with two objectives (1) Screening of wheat genotypes for combined drought and high temperature stress and to identify contrasting set of wheat genotypes on the basis of physiological traits. (2) To study the protective role of cytokinin (6-BAP) on physiological and biochemical traits in contrasting sets of wheat genotypes subjected to combined drought and high temperature stress condition. Complete experiments were performed in 10 days old wheat seedling grown in petri plate. For identification of contrasting genotypes, screening experiments were performed with twenty wheat genotypes. Growth parameters (dry mass accumulation, fresh weight, root length & shoot length per plant) and physiological traits (chlorophyll contents measured in terms of SPAD units), were recorded in 10 days old wheat seedling, and on the basis of growth performance under combined stress condition, one set of contrasting wheat genotypes were identified (C-306, relatively tolerant for combined stress and KO-307, relatively combined stress sensitive). For objective second, two experiments were performed, first experiments were performed to optimize dose of cytokinin using varying levels of benzyl amino purine (BAP; 5, 10 and 20 ppm). Exogenous application of BAP significant increased membrane stability index (MSI) and other growth parameters in wheat seedlings grown under independent and combined stress condition in all the three concentration of cytokinin. However, among three concentrations response of 10 ppm cytokinin application was maximum on all parameters studied. Second experiment were conducted to find out the effect of optimum dose of BAP on physiological (RWC, MSI, CSI, Chlorophyll & carotenoid contents, TBARS contents and SPAD units) and biochemical traits (antioxidant enzyme activity and proline contents) in contrasting sets of wheat genotypes subjected to drought, high temperature & combined drought and high temperature stress in 10 days old wheat seedlings. Results showed that combined stress severely reduced the photosynthetic pigment contents, carotenoids contents, chlorophyll stability, relative water contents, membrane stability compared to individual stress, which were significantly improved by foliar application of 10 ppm of 6-BAP. Reduction was more in sensitive genotypes (KO-307) as compared to tolerant genotypes (C-306). However, the response of KO-307 was more pronounced to exogenous application of BAP compared to C-306. The levels of antioxidant enzyme activity (peroxidase and SOD) and proline were higher under combined stress conditions which were enhanced further by 6-BAP in both the genotypes. Membrane injury and lipid peroxidation were also significantly reduced by the 6-BAP.Overall, combined effect of drought + high temperature stress was more detrimental than the individual stress however, the effect was hypo-additive in nature, which may be due to cross adaptation effect and further exogenous application of cytokinin (6-BAP) ameliorates the adverse affect of combined stress as well individual stress.