Loading...
Kerala Agricultural University, Thrissur
The history of agricultural education in Kerala can be traced back to the year 1896 when a scheme was evolved in the erstwhile Travancore State to train a few young men in scientific agriculture at the Demonstration Farm, Karamana, Thiruvananthapuram, presently, the Cropping Systems Research Centre under Kerala Agricultural University. Agriculture was introduced as an optional subject in the middle school classes in the State in 1922 when an Agricultural Middle School was started at Aluva, Ernakulam District. The popularity and usefulness of this school led to the starting of similar institutions at Kottarakkara and Konni in 1928 and 1931 respectively.
Agriculture was later introduced as an optional subject for Intermediate Course in 1953. In 1955, the erstwhile Government of Travancore-Cochin started the Agricultural College and Research Institute at Vellayani, Thiruvananthapuram and the College of Veterinary and Animal Sciences at Mannuthy, Thrissur for imparting higher education in agricultural and veterinary sciences, respectively. These institutions were brought under the direct administrative control of the Department of Agriculture and the Department of Animal Husbandry, respectively. With the formation of Kerala State in 1956, these two colleges were affiliated to the University of Kerala. The post-graduate programmes leading to M.Sc. (Ag), M.V.Sc. and Ph.D. degrees were started in 1961, 1962 and 1965 respectively.
On the recommendation of the Second National Education Commission (1964-66) headed by Dr. D.S. Kothari, the then Chairman of the University Grants Commission, one Agricultural University in each State was established. The State Agricultural Universities (SAUs) were established in India as an integral part of the National Agricultural Research System to give the much needed impetus to Agriculture Education and Research in the Country. As a result the Kerala Agricultural University (KAU) was established on 24th February 1971 by virtue of the Act 33 of 1971 and started functioning on 1st February 1972. The Kerala Agricultural University is the 15th in the series of the SAUs.
In accordance with the provisions of KAU Act of 1971, the Agricultural College and Research Institute at Vellayani, and the College of Veterinary and Animal Sciences, Mannuthy, were brought under the Kerala Agricultural University. In addition, twenty one agricultural and animal husbandry research stations were also transferred to the KAU for taking up research and extension programmes on various crops, animals, birds, etc.
During 2011, Kerala Agricultural University was trifurcated into Kerala Veterinary and Animal Sciences University (KVASU), Kerala University of Fisheries and Ocean Studies (KUFOS) and Kerala Agricultural University (KAU).
Now the University has seven colleges (four Agriculture, one Agricultural Engineering, one Forestry, one Co-operation Banking & Management), six RARSs, seven KVKs, 15 Research Stations and 16 Research and Extension Units under the faculties of Agriculture, Agricultural Engineering and Forestry. In addition, one Academy on Climate Change Adaptation and one Institute of Agricultural Technology offering M.Sc. (Integrated) Climate Change Adaptation and Diploma in Agricultural Sciences respectively are also functioning in Kerala Agricultural University.
Browse
30 results
Search Results
ThesisItem Open Access Comparative assessment of climate resilient capacity of two indigenous goat breeds based on changes in both phenotypic and genotypic traits(Academy of Climate Change Education and Research, Vellanikkara, 2020) Reshma Nair, M R; KAU; Sejian, VThesisItem Open Access Development of encapsulated formulation of PGPR mix-I and IRS evaluation(Department of Agricultural Microbiology, College of Agriculture, Vellayani, 2020) Ayisha, Y L; KAU; Meenakumari, K SThe study entitled “Development of encapsulated formulation of PGPR mix-I and its evaluation” was conducted during 2018-2020, in the Department of Agricultural Microbiology, College of Agriculture, Vellayani, Thiruvananthapuram, with the objective to develop calcium alginate based encapsulated formulation of PGPR mix-I and its evaluation for slow release and biodegradation. The component cultures of PGPR mix-I were procured from the Department of Agricultural Microbiology, College of Agriculture, Vellayani for standardization of protocol for preparation of calcium alginate based encapsulated bead formulation of PGPR mix-I. Encapsulated bead formulation of PGPR mix-I was prepared by standard procedures. An experiment was carried out to standardize the protocol for preparation of calcium alginate based encapsulated formulation of PGPR mix–I in completely randomized design with different treatments such as 10% Standard starch, 15% Standard starch, 10% Wheat flour, 15% Wheat flour, 10% Talc, 15% Talc and control treatment as 2% Sodium alginate alone in three replications. Consistent viable count was recorded in encapsulated formulation amended with 10% Standard starch. It exhibited maximum viable count of each of the component cultures of PGPR mix-I as a result of three month population study. A significant decline of total viable population in control treatment was observed in each month compared to encapsulated formulation amended with 10% Standard starch. Based on the population study, encapsulated formulation of PGPR mix-I 10% Standard starch amended was adjudged as the best combination of filler material and hence the shelf life studies of the same had to be continued at monthly intervals at room temperature and refrigerated conditions for six months by serial dilution and plate count method. Significant viable count was recorded in encapsulated beads stored at room temperature condition throughout the shelf life study. The moisture content of beads were also monitored during standardization and shelf life study. During standardization study, moisture content of PGPR mix-I encapsulated beads of each treatment was monitored for a period of three months at monthly intervals at room temperature and it showed a significant variation among treatments in each month. A reduction in moisture content of beads was observed from first month to the end of sixth month in all treatments. Beads amended with 10% Standard starch showed a moisture content of 13.37%, 12.07%, 11.72% and 11.45% after 24 hours of drying, first, second and third month respectively. During shelf life study, 10% Standard starch combination at refrigerated condition showed moisture content in the range of 12.83% to 11.45% while at room temperature the same has recorded values in the range of 12.07% to 10.70%. Evaluation of rate of release of immobilized bacteria from encapsulated beads was determined as per the procedure described by Bashan (1986) and the number of released bacteria was determined by the plate count method in respective selective medium. The higher cfu of component cultures of PGPR mix-I was observed after gentle shaking at 32⁰C for 24hours (T1) in75ml of sterile saline solution. Evaluation of biodegradation of encapsulated beads was studied at weekly intervals in sterile and non-sterile soil with PGPR mix-I inoculated and non-inoculated beads with three replications each (Bashan, 1986). Both the sets were observed weekly for their rate of biodegradation. As per biodegradation scale values like 0, ˃0-0.5, ˃0.5-1, ˃1-2, ˃2-2.5 or 3 was assigned according to the degree of visible degradation which indicates no visible degradation,onset of degradation, slight visible degradation on bead edges, one-half to three-fourth of the beads degraded, 90% of beads become mushy, full degradation (beads are disintegrated into small pieces or not found in the nylon bag) repectively (Bashan, 1986). The PGPR mix-I inoculated beads with bacteria in non-sterile soil showed highest scale of biodegradation throughout the biodegradation study (mean value 1.34) and beads without bacteria in sterile soil showed the lowest scale (mean value 0.52). Kruskal-Wallis rank sum test was done and there was a significant difference between treatments and so multiple comparison was done using Dunn test. During all the four weeks of biodegradation study, treatment T1 (beads with PGPR mix-I in non sterile soil) recorded the highest biodegradation and T4 (beads without PGPR mix-I in sterile soil) recorded the least biodegradation. Treatments T2 (beads with PGPR mix-I in sterile soil) and T3 (beads without PGPR mix-I in non sterile) were on par with both the treatments T1 and T4 in all the four weeks. Treatment wise evaluation of biodegradation of beads was done with Kruskal-Wallis rank sum test and gives a chi-squared value of 46.205 with df = 15 and p-value = 4.932e-05. There was a significant difference between treatments and so multiple comparison was done using Dunn test. Treatment T4 (beads with bacteria in non sterile soil during fourth week) showed significantly different from treatment T13 (beads without bacteria in sterile soil during first week). In the present investigation, calcium alginate based encapsulated beads of PGPR mix-I amended with 10% Standard starch exhibited maximum viable count of component cultures of PGPR mix-I throughout the three months period of standardization study. In terms of evaluation of shelf life and moisture retention during storage, beads stored under room temperature condition was found to be better. The rate of release of component cultures of PGPR mix-I from the encapsulated formulation was more during the first 24-48 hours. Biodegradation studies of encapsulated beads of PGPR mix-I revealed that the beads inoculated with PGPR mix-I in non sterile soil showed highest biodegradation throughout the period of investigation.ThesisItem Open Access Field evaluation of abiotic stress tolerant strains of Trichoderma harzianum and Pseudomonas fluorescens for Phytophthora disease management in black paper (Piper nigrum L.)(Department of Agricultural Microbiology, College of Horticulture, Vellanikkara, 2020) Rima, K R.; KAU; Surendra Gopal, KBlack pepper (Piper nigrum L.), known as “the king of spices” is an important spice commodity of commerce and trade in India since pre-historic period. It is highly sensitive to abiotic stresses like climate changes. The abiotic stresses in plants can be overcome by the use of beneficial microorganisms. However, the microorganisms themselves are vulnerable to abiotic and biotic stresses. Therefore, abiotic stress tolerant strains of beneficial microorganisms have to be developed for black pepper to overcome changes due to micro-climatic variables and soil parameters. In an earlier study in the Department of Agricultural Microbiology, College of Horticulture, native abiotic stress tolerant isolates of Trichoderma harzianum (CKT isolate) and Pseudomonas fluorescens (PAP isolate) were identified for growth promotion and disease management in black pepper (Piper nigrum L.) under pot culture studies. As the performance of these strains varies under field conditions, a study on “Field evaluation of abiotic stress tolerant strains of Trichoderma harzianum and Pseudomonas fluorescens for Phytophthora disease management in black pepper (Piper nigrum L.)” was undertaken with an objective to study the effect of micro- climatic and soil parameters on abiotic stress tolerant strains under field conditions. Before field evaluation, pot culture experiment was conducted to evaluate the efficiency of the abiotic stress tolerant Trichoderma harzianum (CKT) and Pseudomonas fluorescens (PAP) for growth promotion and Phytophthora disease management in black pepper during April – October, 2017. T. harzianum (CKT) was the most promising isolate for growth promotion and disease management based on biometric (number of leaves, plant height, number of lateral branches, number of nodes, intermodal length), biological and disease management characters under pot culture studies. It was found that population of Trichoderma harzianum (CKT), Pseudomonas fluorescens (PAP), Trichoderma viride (KAU reference culture) and Pseudomonas fluorescens (KAU reference culture) was negatively correlated with soil temperature and positively correlated with soil moisture. There was no significant correlation between the population of microbes and soil pH and soil respiration. Field evaluation revealed that Trichoderma harzianum (CKT) + KAU POP was the most promising treatment for growth promotion under field conditions based on biometric and biological characters. The population of Trichoderma harzianum (CKT), Pseudomonas fluorescens (PAP), Trichoderma viride (KAU reference culture) and Pseudomonas fluorescens (KAU reference culture) were negatively correlated with soil temperature and positively correlated with soil moisture content. However, soil pH and soil respiration did not have any correlation with the population of Trichoderma sp. and Pseudomonas fluorescens. Micro-climatic and soil parameters did not show any effect on the production of ammonia, HCN and siderophore but had significant effect on production of IAA in Trichoderma sp. and Pseudomonas fluorescens. Soil temperature (26.8 to 30.6 °C), soil moisture content (14 to 17.6 %), soil pH (5.7 to 6.1) and soil respiration (8.1 to 9.8 mg CO2 g-1 day-1) were found to be the optimum micro-climatic and soil parameters for IAA production. Trichoderma harzianum (CKT) was the most promising isolate for growth promotion under field conditions. However, multilocational field trials at different agro- ecological zones of Kerala need to be conducted before commercialization of Trichoderma harzianum (CKT).ThesisItem Open Access Isolation and in vitro screening of silicate solubilizing bacteria from paddy rhizosphere(Department of Agricultural Microbiology, College of Agriculture, Vellayani, 2020) Akhila P, Subash.; KAU; Meenakumari, K SThe study entitled “Isolation and in vitro screening of silicate solubilizing bacteria from paddy rhizosphere”, was conducted during 2018-2020, in the Department of Agricultural Microbiology, College of Agriculture, Vellayani, Thiruvananthapuram, with the objective of isolation and in vitro screening of bacteria which are capable of solubilizing insoluble form of silicate. Bacteria capable of solubilizing silicates were isolated from the rhizosphere soils collected from different upland and low land paddy fields by serial dilution and plate count method using Bunt and Rovira medium supplemented with 0.25 per cent magnesium trisilicate. Based on the clear halo zone formed around the bacterial colonies on solid media, they were identified as Silicate Solubilizing Bacteria (SSB). Twenty seven isolates of bacteria capable of solubilizing insoluble form of silicate (magnesium trisilicate) were obtained from different locations and were allotted code numbers from SSB 1 to SSB 27. These isolates were subjected to plate and broth assay in Bunt and Rovira medium supplemented with 0.25 per cent magnesium trisilicate. After three days of incubation of test plates at room temperature, all the twenty seven isolates solubilized magnesium trisilicate and produced clearing zone around the bacterial colonies on solid media. The size of clearance zone ranged from 3 mm to 13 mm in plates. The maximum clearance zone of 13 mm was recorded with the isolate SSB 14 which was significantly superior to all other isolates. In broth culture, SSB 20 showed the highest silicate solubilization of 94.65 mg L-1. Based on plate as well as broth assay of all the twenty seven isolates obtained, five isolates viz., SSB 3, SSB 14, SSB 18, SSB 20 and SSB 22 which showed the maximum clearance zone in plate and silicate solubilization in broth were selected as superior isolates. All the isolates obtained were subjected to plate and broth assay for phosphate solubilization in Pikovskaya’s medium and potassium solubilization in Aleksandrov medium. Among them, fourteen isolates showed phosphate solubilization in plates and the clearance zone ranged from 0.87 mm to 5.50 mm. The maximum clearance zone of 5.50 mm was recorded with the isolate SSB 22 which was on par with SSB 23 with 5 mm clearance zone in plate and highest solubilization of 41.92 mg L-1 in broth was shown by SSB 22 which was significantly superior to all other isolates. Twelve isolates showed potassium solubilization in plates and the clearance zone ranged from 2.25 mm to 5.50 mm. Maximum clearance zone of 5.50 mm was recorded with the isolate SSB 8 which was significantly superior to all other isolates. The highest potassium solubilization of 37.50 mg L-1 in broth was observed with isolates SSB 1, SSB 2, SSB 7, SSB 8, SSB 13, SSB 18, SSB 21 and SSB 22 which were found to be statistically on par. Acid production by the five superior SSB isolates, SSB 3, SSB 14, SSB 18, SSB 20 and SSB 22 was detected as a yellow halo around the bacterial colonies in bromophenol blue amended Bunt and Rovira medium. All the five superior isolates tested showed positive results for acid production. The antagonistic activity of the five superior SSB isolates were assessed against major pathogens of paddy viz., Rhizoctonia solani, Magnaporthe grisea, Helminthosporium oryzae and Xanthomonas oryzae pv. oryzae following dual culture method. Out of the five isolates tested, three isolates (SSB 18, SSB 20 and SSB 22) inhibited Rhizoctonia solani. Three isolates (SSB 3, SSB 18 and SSB 22) showed antagonism against Magnaporthe grisea and four isolates (SSB 3, SSB 18, SSB 20 and SSB 22) inhibited Helminthosporium oryzae. The bacterial pathogen, Xanthomonas oryzae pv. oryzae was inhibited by three isolates (SSB 18, SSB 20 and SSB 22). Among all the five isolates tested against different phytopathogens, SSB 18 was found superior with the maximum zone of inhibition of 9.65 mm, 14.45 mm, 10.80 mm and 11.50 mm against Rhizoctonia solani, Magnaporthe grisea, Helminthosporium oryzae and Xanthomonas oryzae pv. oryzae respectively. The five superior isolates were characterized based on morphological and biochemical characters. The results revealed that all the isolates were rod shaped, Gram positive endospore formers. Based on the results of present study, it can be concluded that SSB 3, SSB 14, SSB 18, SSB 20 and SSB 22 are the superior silicate solubilizing bacterial isolates. Among them, SSB 18 showed the highest antagonistic activity against major pathogens of paddy.ThesisItem Open Access Development of encapsulated formulation of PGPR mix-I and its evaluation(Department of Agricultural Microbiology, College of Agriculture, Vellayani, 2020) Ayisha, Y L; KAU; Meenakumari, K SThe study entitled “Development of encapsulated formulation of PGPR mix-I and its evaluation” was conducted during 2018-2020, in the Department of Agricultural Microbiology, College of Agriculture, Vellayani, Thiruvananthapuram, with the objective to develop calcium alginate based encapsulated formulation of PGPR mix-I and its evaluation for slow release and biodegradation. The component cultures of PGPR mix-I were procured from the Department of Agricultural Microbiology, College of Agriculture, Vellayani for standardization of protocol for preparation of calcium alginate based encapsulated bead formulation of PGPR mix-I. Encapsulated bead formulation of PGPR mix-I was prepared by standard procedures. An experiment was carried out to standardize the protocol for preparation of calcium alginate based encapsulated formulation of PGPR mix–I in completely randomized design with different treatments such as 10% Standard starch, 15% Standard starch, 10% Wheat flour, 15% Wheat flour, 10% Talc, 15% Talc and control treatment as 2% Sodium alginate alone in three replications. Consistent viable count was recorded in encapsulated formulation amended with 10% Standard starch. It exhibited maximum viable count of each of the component cultures of PGPR mix-I as a result of three month population study. A significant decline of total viable population in control treatment was observed in each month compared to encapsulated formulation amended with 10% Standard starch. Based on the population study, encapsulated formulation of PGPR mix-I 10% Standard starch amended was adjudged as the best combination of filler material and hence the shelf life studies of the same had to be continued at monthly intervals at room temperature and refrigerated conditions for six months by serial dilution and plate count method. Significant viable count was recorded in encapsulated beads stored at room temperature condition throughout the shelf life study. The moisture content of beads were also monitored during standardization and shelf life study. During standardization study, moisture content of PGPR mix-I encapsulated beads of each treatment was monitored for a period of three months at monthly intervals at room temperature and it showed a significant variation among treatments in each month. A reduction in moisture content of beads was observed from first month to the end of sixth month in all treatments. Beads amended with 10% Standard starch showed a moisture content of 13.37%, 12.07%, 11.72% and 11.45% after 24 hours of drying, first, second and third month respectively. During shelf life study, 10% Standard starch combination at refrigerated condition showed moisture content in the range of 12.83% to 11.45% while at room temperature the same has recorded values in the range of 12.07% to 10.70%. Evaluation of rate of release of immobilized bacteria from encapsulated beads was determined as per the procedure described by Bashan (1986) and the number of released bacteria was determined by the plate count method in respective selective medium. The higher cfu of component cultures of PGPR mix-I was observed after gentle shaking at 32⁰C for 24hours (T1) in75ml of sterile saline solution. Evaluation of biodegradation of encapsulated beads was studied at weekly intervals in sterile and non-sterile soil with PGPR mix-I inoculated and non-inoculated beads with three replications each (Bashan, 1986). Both the sets were observed weekly for their rate of biodegradation. As per biodegradation scale values like 0, ˃0-0.5, ˃0.5-1, ˃1-2, ˃2-2.5 or 3 was assigned according to the degree of visible degradation which indicates no visible degradation,onset of degradation, slight visible degradation on bead edges, one-half to three-fourth of the beads degraded, 90% of beads become mushy, full degradation (beads are disintegrated into small pieces or not found in the nylon bag) repectively (Bashan, 1986). The PGPR mix-I inoculated beads with bacteria in non-sterile soil showed highest scale of biodegradation throughout the biodegradation study (mean value 1.34) and beads without bacteria in sterile soil showed the lowest scale (mean value 0.52). Kruskal-Wallis rank sum test was done and there was a significant difference between treatments and so multiple comparison was done using Dunn test. During all the four weeks of biodegradation study, treatment T1 (beads with PGPR mix-I in non sterile soil) recorded the highest biodegradation and T4 (beads without PGPR mix-I in sterile soil) recorded the least biodegradation. Treatments T2 (beads with PGPR mix-I in sterile soil) and T3 (beads without PGPR mix-I in non sterile) were on par with both the treatments T1 and T4 in all the four weeks. Treatment wise evaluation of biodegradation of beads was done with Kruskal-Wallis rank sum test and gives a chi-squared value of 46.205 with df = 15 and p-value = 4.932e-05. There was a significant difference between treatments and so multiple comparison was done using Dunn test. Treatment T4 (beads with bacteria in non sterile soil during fourth week) showed significantly different from treatment T13 (beads without bacteria in sterile soil during first week). In the present investigation, calcium alginate based encapsulated beads of PGPR mix-I amended with 10% Standard starch exhibited maximum viable count of component cultures of PGPR mix-I throughout the three months period of standardization study. In terms of evaluation of shelf life and moisture retention during storage, beads stored under room temperature condition was found to be better. The rate of release of component cultures of PGPR mix-I from the encapsulated formulation was more during the first 24-48 hours. Biodegradation studies of encapsulated beads of PGPR mix-I revealed that the beads inoculated with PGPR mix-I in non sterile soil showed highest biodegradation throughout the period of investigation.ThesisItem Open Access Plant associated endospore forming bacteria from amaranthus as growth promoters and biocontrol agents against rhizoctonia leaf blight(Department of Agricultural Microbiology, college of Agriculture, Vellayani, 2020) Yashwasini, M S; KAU; Anith, K NThe study entitled “Plant associated endospore forming bacteria from amaranthus as growth promoters and biocontrol agents against Rhizoctonia leaf blight”, was conducted during 2018-2020, in the Department of Agricultural Microbiology, College of Agriculture, Vellayani, Thiruvananthapuram, with the objective of isolation and characterization of endospore forming bacteria from endorhizosphere and phyllosphere of Amaranthus and evaluate their effect on growth promotion and disease suppression. Endospore forming bacteria from endorhizosphere and phyllosphere were isolated from healthy roots and leaves of red amaranthus variety Arun, green amaranthus var. CO1 and wild relative (Amaranthus viridis) respectively by enrichment method on NA medium. A total of eight endospore forming bacterial isolates were obtained each from endorhizosphere and phyllosphere of the variety Arun, variety CO-1 and wild relative (Amaranthus viridis). All the isolates were identified as Bacillus spp. based on morphological, biochemical and molecular characterization. These isolates designated as AR1, AR2, AR3, GR1, GR2, GR3, WR1, WR2, AL1, AL2, AL3, GL1, GL2, GL3, WL1 and WL2 were identified as Bacillus sp., Bacillus siamensis, Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus amyloliquefaciens, Bacillus amyloliquefaciens, Bacillus sp., Bacillus amyloliquefaciens, Bacillus sp., Bacillus subtilis, Bacillus sp., Bacillus amyloliquefaciens, Bacillus sp., Bacillus sp., Bacillus subtilis and Bacillus amyloliquefaciens respectively based on 16S rRNA sequence. Indole Acetic Acid production by the different endospore forming endorhizosphere bacterial isolates ranged from 4.09 to 9.73 μg mL-1 of culture filtrate. The isolate AR3 produced the maximum IAA of 9.73 μg mL-1 of culture filtrate. In roll towel assay significant increase in germination percentage, seedling shoot length, root length and seedling vigour index compared to control was observed when seeds were treated with the endospore forming endorhizosphere bacterial isolates. Isolate WR1 showed the maximum germination (43.33%) whereas control recorded a germination of 30%. Isolate WR1 showed maximum seedling vigour index (223.66) compared to the control (136.53). A portray experiment was also conducted to study the influence of endospore forming endorhizosphere bacterial isolates on plant growth parameters of amaranthus in the nursery stage. Highest root length was observed in the seedlings treated with isolate GR1 (4.76 cm) whereas the control recorded 3.91 cm. Shoot length was the maximum in seeds treated with WR1 (6.34 cm) whereas control recorded a shoot length of 5.59 cm. Maximum germination percentage of 100 was obtained in seeds treated with the isolate WR2. Significant influence of the bacterial isolates on seedling vigour index was observed wherein the isolate WR2 recorded maximum of 884.50. Highest root fresh weight was recorded in the plants treated with isolate GR1 (8.12 mg/plant) and the lowest root fresh weight of 3.56 mg/plant was recorded in control plants. It was found that the highest root dry weight was found in plants treated with isolate WR1 (2.99 mg/plant) as against the control (2.46 mg/plant). Dual culture plate assay was carried out on Potato Dextrose Agar medium to check the ability of endospore forming phyllopshere bacterial isolates to inhibit Rhizoctonia solani causing foliar blight disease. All the isolates inhibited the mycelial growth of Rhizoctonia solani, of which GL3 and GL1 exhibited the maximum and minimum zone of inhibition (ZOI) of 8.73 and 1.00 mm respectively. All the endospore forming phyllopshere bacterial isolates tested for their indirect antagonism inhibited Rhizoctonia solani mycelial growth, of which isolate GL3 showed the maximum ZOI of 2.88 mm and the minimum was recorded by the isolate GL1 (0.50 mm). In detached leaf assay, significant difference was noticed in the lesion size appeared on the detached leaves treated with endospore forming phyllosphere bacterial isolates and water (control) on 3rd and 4th day after pathogen inoculation. Control exhibited maximum lesion area of 3.49 and 12.23 cm2 and the minimum lesion area of 0.42 and 3.11 cm2 was developed on the leaves treated with isolate WL2 on 3rd and 4th day after pathogen inoculation respectively. Based on in vitro studies on plant growth promotion and antagonistic activity against R. solani the endospore forming endorhizosphere bacterial isolates AR1, AR2, GR1, GR2, WR1 and WR2 and endospore forming phyllosphere bacterial isolates - AL1, AL3, GL2, GL3, WL1 and WL2 were selected for further pot culture study. A pot culture experiment was conducted to evaluate the efficacy of selected endospore forming endorhizosphere bacteria for their plant growth promoting activity in Amaranthus (var. Arun). Endospore forming endorhizosphere bacteria inoculated plants showed significant increase in biometric parameters such as number of leaves, number of branches, plant height and dry matter production compared to control. Plants treated with Bacillus amyloliquefaciens GR1 exhibited the maximum shoot fresh weight of 54.30 g/plant, whereas the control plants showed the minimum of 40.24 g/plant. Shoot dry matter production was maximum with plants treated with the isolate AR2 (6.74 g/plant) and the control plants recorded 4.76 g/plant. Bacillus amyloliquefaciens GR1 treated plants produced maximum root fresh weight of 13.64 g/plant, whereas the control plants had root fresh weight of 9.88 g/plant. Maximum root dry weight was exhibited by plants treated with Bacillus amyloliquefaciens GR1 (1.98 g/plant), lowest was produced by control plants with 1.37 g/plant. Suppression of Rhizoctonia leaf blight in the variety Arun treated with selected endospore forming phyllosphere bacterial isolates was studied by challenge inoculation with the pathogen on intact leaves. The bacterial suspension containing bacterial cells of concentration 107 cfu ml-1 was sprayed on to the intact leaves of plants one week prior to pathogen inoculation. On 3rd day after pathogen inoculation, plants treated with Bacillus sp GL3 showed the minimum percent disease index of 11.80 with 32.92% disease 11.80 with 32.92% disease 11.80 with 32.92% disease 11.80 with 32.92% disease 11.80 with 32.92% disease 11.80 with 32.92% disease 11.80 with 32.92% disease 11.80 with 32.92% disease suppression over the pathogen co suppression over the pathogen co suppression over the pathogen co suppression over the pathogen co suppression over the pathogen co suppression over the pathogen co suppression over the pathogen co suppression over the pathogen co suppression over the pathogen cosuppression over the pathogen control, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the ntrol, which was on par with the Bacillus sp AL3 with with 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. 11.81 percent disease index. No symptom development was observed in absolute control. On 5th day after pathogen inoculation, Bacillus sp AL3 treated plants showed the minimum percent disease index of 18 .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the .75 with 44.51% disease suppression over the pathogen inoculated control. pathogen inoculated control. pathogen inoculated control. pathogen inoculated control. pathogen inoculated control. pathogen inoculated control. The present study revealed that seed bacterization of amaranthus plants with endospore forming endorhizosphere and foliar spray of phyllosphere bacterial isolates improved plant growth and suppressed Rhizoctonia solani leaf blight incidence respectively and helps in better establishment of plants. Bacillus amyloliquefaciens GR1 and Bacillus sp AL3 were selected as the best isolates for plant growth promotion and disease suppression respectively.ThesisItem Open Access Plant growth promotion and foot rot disease suppression in black pepper using fungal and bacterial endophytes(Department of Agricultural Microbiology, college of Agriculture, Vellayani, 2020) Teenu, Paul; KAU; Anith, K NThe study entitled “Plant growth promotion and foot rot disease suppression in black pepper using fungal and bacterial endophytes” was conducted in the Department of Agricultural Microbiology, College of Agriculture, Vellayani during the period 2018 – 2020. The objective of the study was to assess and evaluate the compatibility of the root endophytic fungus Piriformospora indica and two endophytic bacterial strains Bacillus velezensis PCSE 10 and Rhizobium radiobacter PCRE 10 and their effect on growth promotion in bush pepper and foot rot disease suppression in black pepper. Experiments comprised both in vitro and in vivo studies. In vitro interaction of bacterial bioagents and P. indica using dual culture plate assay was done to assess the compatibility between them. In PDA plates B. velezensis PCSE10 inhibited the growth of P. indica with an inhibition zone of 4 mm on 6th day after bacterial inoculation. Virulent isolate of foot rot pathogen Phytophthora capsici was isolated from infected black pepper leaves on PDA medium. The pathogenicity of the strain was proved by artificial inoculation on black pepper leaves. In vitro antagonism shown by the bacterial bioagents against the pathogen was evaluated using dual culture plate assay. All the three bioagents were found to have in vitro antagonism against P. capsici. In the dual culture plate assay zone of inhibition was produced by B. velezensis PCSE 10 (4.67 mm) and R. radiobacter PCRE 10 (1.03 mm). The dual culture plate assay was followed by a detached leaf assay using the two endophytic bacterial isolates. There was significant difference in lesion size on control leaves sprayed with sterile water and leaves sprayed with the selected isolates. The minimum lesion size was observed in leaves treated with R. radiobacter PCRE10 (1.43 cm) which caused 52.33 % disease suppression over control which was on par with leaves treated with B. velezensis PCSE 10 with lesion size of 2.18 cm and 27.33% disease suppression over control. The maximum lesion size was observed in control leaves sprayed with distilled water (3.0 cm). Both the isolates produced IAA under in vitro conditions. R. radiibacter PCRE 10 was found to produce 4.62 μg/ml and 8.79 μg/ ml IAA without and with L- Trypthophan respectively. B. velezensis PCSE 10 produced 3.77 μg/ml and 4.92 μg/ml IAA in absence and presence of L- Tryptophan respectively. R. radiobacter PCRE 10 was also positive for ammonia production. A pot culture experiment was conducted to study the effect of the different treatments on growth promotion and foot rot suppression in bush pepper. The experiment was laid out in CRD with six treatments and three replications and observations were taken at 30 days interval. The treatments comprised fungal and bacterial endophytes individually along with combinations of both fungal and bacterial endophytes and an uninoculated control. Bioagents were applied during the production of rooted cuttings and plants transplanted to pots filled with unsterile garden soil. The plant growth promotion aspects of the endophytes were studied by analysing the biometric characters of bush pepper var. Panniyur -1 at monthly intervals. The results revealed that the maximum leaf number was observed in plants treated with combination of P. indica and R. radiobacter PCRE10. Maximum leaf area per plant was recorded in the treatment with combination of P. indica and R. radiobacter PCRE 10 at fourth month after transplanting. Single application of P. indica resulted in the highest spike length. The highest number of spikes harvested per plant was recorded in the treatment with combination of P. indica and R. radiobacter PCRE 10. When the berry fresh weight and dry weight were analyzed statistically, there was no significant difference observed among the treatments. The highest value was recorded in the treatment involving single application of P. indica. Plants treated with P. indica alone showed highest root colonization of 35.50 percent followed by combination by P. indica and B. velezensis (31.11 per cent) and P. indica and R. radiobacter PCRE10 (19.35 percent). Suppression of foliar infection by P. capsici in plants treated with the individual endophytes and their combination was studied by challenge inoculation with the pathogen on the foliage. Following artificial inoculation with the pathogen, the lowest lesion size was observed in plants treated with combination of P. indica and R. radiobacter PCRE10 (0.44 cm) which caused 33.33% disease suppression over the pathogen control with the lowest disease index of 0.2. The in vivo study for plant growth promotion revealed that plants treated with combination of P. indica along with R. radiobacter PCRE10 and single inoculation of P. indica performed better than all other treatments. സംഗ്രഹം വെള്ളായണി കാർഷിക കോളേജിലെ കാർഷിക മൈക്രോബയോളജി വിഭാഗത്തിൽ 2018 - 2020 കാലയളവിൽ “കുമിൾ, ബാക്ടീരിയൽ എൻഡോഫൈറ്റുകൾ ഉപയോഗിച്ച് കുരുമുളക് ചെടികളുടെ വളർച്ച പ്രോത്സാഹനം, കാൽ ചെംചീയൽ രോഗം അടിച്ചമർത്തൽ” എന്ന തലക്കെട്ടിലുള്ള പഠനം നടത്തി. റൂട്ട് എൻഡോഫൈറ്റിക് കുമിളായ പിരിഫോർമോസ്പോറ ഇൻഡിക്കയും, ബാസിലസ് വെലെസെൻസിസ് പിസിഎസ്ഇ 10, റൈസോബിയം റേഡിയോബാക്റ്റർ പിസിആർഇ 10 എന്നി രണ്ട് എൻഡോഫൈറ്റിക് ബാക്ടീരിയകളും തന്നിലുള്ള അനുയോജ്യതയും കുറ്റി കുരുമുളകിലെ വളർച്ചയെ പ്രോത്സാഹിപ്പിക്കുന്നതിലും കാൽ ചെംചീയൽ രോഗത്തെ അടിച്ചമർത്തുന്നതിലും ഉള്ള കഴിവ് വിലയിരുത്തുകയും ചെയ്യുകയായിരുന്നു പഠനത്തിന്റെ ലക്ഷ്യം. ബാക്ടീരിയൽ ബയോജെന്റുകളുടെയും പിരിഫോർമോസ്പോറ ഇൻഡിക്കയും തമ്മിലുള്ള അനുയോജ്യത വിലയിരുത്തുന്നതിനായി ഡ്യുവൽ കൾച്ചർ പ്ലേറ്റ് അസ്സെ ഉപയോഗിച്ചു. പിഡിഎ പ്ലേറ്റുകളിൽ ബാസിലസ് വെലെസെൻസിസ് പിസിഎസ്ഇ 10, പിരിഫോർമോസ്പോറ ഇൻഡിക്കയുടെ വളർച്ചയെ തടഞ്ഞു. കാൽ ചെംചീയൽ രോഗകാരിയായ കുമിൾ ബാധിച്ച കുരുമുളക് ഇലകളിൽ നിന്നും ഫൈറ്റോപ്തോറ കാപ്സിസി, പിഡിഎ എന്ന മാധ്യമം ഉപയോഗിച്ച് വേർതിരിച്ചു. കുരുമുളക് ഇലകളിൽ കൃത്രിമ കുത്തിവയ്പ്പിലൂടെ സമ്മർദ്ദത്തിന്റെ രോഗകാരിത്വം തെളിഞ്ഞു. ഡ്യുവൽ കൾച്ചർ പ്ലേറ്റ് അസ്സെ ഉപയോഗിച്ച് രോഗകാരിക്കെതിരായ ബയോ ഏജന്റുകൾ കാണിച്ച ഇൻ വിട്രോ വൈരാഗ്യം വിലയിരുത്തി. മൂന്ന് ബയോ ഏജന്റുമാർക്കും ഫൈറ്റോപ്തോറ കാപ്സി ക്കെതിരെ ഇൻ വിട്രോ വൈരാഗ്യമുണ്ടെന്ന് കണ്ടെത്തി. ഡ്യുവൽ കൾച്ചർ പ്ലേറ്റ് അസ്സെയ്ക്ക് ശേഷം രണ്ട് എൻഡോഫൈറ്റിക് ബാക്ടീരിയകളും ഉപയോഗിച്ച് വേർതിരിച്ച ഇലയി ൽ പരിശോധന നടത്തി. അണുവിമുക്തമായ വെള്ളത്തിൽ തളിക്കുന്ന നിയന്ത്രണ ഇലകളിലും ബാക്ടീരിയ തളിക്കുന്ന ഇലകളിലും നിഖേദ് വലുപ്പത്തിൽ കാര്യമായ വ്യത്യാസമുണ്ട്. റൈസോബിയം റേഡിയോബാക്റ്റർ പിസിആർഇ 10 (1.43 സെ.മീ) ഉപയോഗിച്ച് ചികിത്സിച്ച ഇലകളിലാണ് ഏറ്റവും കുറഞ്ഞ നിഖേദ് വലുപ്പം കണ്ടെത്തിയത്.രണ്ട് ബാക്ടീരിയകളും ഇൻ വിട്രോ സാഹചര്യങ്ങളിൽ ഇൻഡോൾ അസെറ്റിക് ആസിഡ് ഉൽപാദിപ്പിച്ചു. റൈസോബിയം റേഡിബാക്റ്റർ പിസിആർഇ 10 യഥാക്രമം മൈക്രോഗ്രാം/ മില്ലി, 4.62 മൈക്രോഗ്രാം/ മില്ലി എൽ-ട്രിപ്റ്റോഫാൻ സാന്നിധ്യത്തിലും അസാന്നിധ്യത്തിലും ഉൽപാദിപ്പിക്കുന്നതായി കണ്ടെത്തി. റൈസോബിയം റേഡിയോബാക്റ്റർ പിസിആർഇ 10 അമോണിയ ഇൻ വിട്രോ ഉൽപാദിപ്പിച്ചു. കുറ്റി കുരുമുളകിന്റെ വളർച്ച പ്രോത്സാഹിപ്പിക്കുന്നതിലും കാൽ ചെംചീയൽ അടിച്ചമർത്തുന്നതിലുമുള്ള വ്യത്യസ്ത ചികിത്സകളുടെ ഫലത്തെക്കുറിച്ച് പഠിക്കാൻ ഒരു പോട്ട് കൾച്ചർ പരീക്ഷണം നടത്തി. ആറ് ചികിത്സകളോടെ പൂർണ്ണമായും ക്രമരഹിതമായ ഡിസൈനിൽ പരീക്ഷണം നടത്തി. കുമീൾ, ബാക്ടീരിയ എൻഡോഫൈറ്റുകൾ എന്നിവയുടെ ഒറ്റയായ പ്രയോഗവും, കൂടാതെ അവയുടെ സംയോജനവും, നിയന്ത്രണാതീതമായ നിയന്ത്രണവും ചികിത്സയിൽ ഉൾപ്പെടുന്നു. വേരുറപ്പിക്കാനായി തണ്ടുകൾ കൂടയിൽ നടുന്ന സമയത്തും വേരുറപ്പിച്ച ചെടികൾ അസ്ഥിരമായ തോട്ടം മണ്ണ് നിറച്ച ചട്ടിയിലേക്ക് പറിച്ചു നടുന്ന സമയത്തും എന്നിവയുടെ ഉൽപാദനത്തിൽ ബയോ ഏജന്റുകൾ പ്രയോഗിച്ചു. കുറ്റി കുരുമുളക് ഇനം പന്നിയൂർ 1 ന്റെ ബയോമെട്രിക് പ്രതീകങ്ങൾ വിശകലനം ചെയ്തുകൊണ്ട് എൻഡോഫൈറ്റുകളുടെ സസ്യവളർച്ച പ്രോത്സാഹന വശങ്ങൾ പ്രതിമാസ ഇടവേളകളിൽ പഠിച്ചു. പിരിഫോർമോസ്പോറ ഇൻഡിക്ക, റൈസോബിയം റേഡിയോബാക്റ്റർ പിസിആർഇ 10 എന്നിവയുടെ സംയോജനത്തിൽ ചികിത്സിച്ച സസ്യങ്ങളിൽ പരമാവധി ഇല വിസ്തീർണ്ണം ഇലകളുടെ എണ്ണം കണ്ടെത്തിയതായി ഫലങ്ങൾ വെളിപ്പെടുത്തി. പിരിഫോർമോസ്പോറ ഇൻഡിക്കയുടെ ഒറ്റയ്ക്കുളള ആപ്ലിക്കേഷൻ ഏറ്റവും ഉയർന്ന തിരി ദൈർഘ്യത്തിന് കാരണമായി. പിരിഫോർമോസ്പോറ ഇൻഡിക്കയിൽ മാത്രം ചികിത്സിച്ച സസ്യങ്ങൾ ഏറ്റവും ഉയർന്ന റൂട്ട് കോളനിവൽക്കരണം 35.50 ശതമാനം രേഖപ്പെടുത്തി. വ്യക്തിഗത എൻഡോഫൈറ്റുകളും അവയുടെ സംയോജനവും ചികിത്സിക്കുന്ന സസ്യങ്ങളിൽ ഫൈറ്റോപ്തോറ കാപ്സിസി ഫോളിയർ അണുബാധയെ അടിച്ചമർത്താനുള്ള ശേഷിയെ പറ്റി പഠനം നടത്തുകയും ചെയ്തു. രോഗകാരിയായ കുമിളിൻറെ കൃത്രിമ കുത്തിവയ്പ്പിനെത്തുടർന്ന്, പിരിഫോർമോസ്പോറ ഇൻഡിക്ക, റൈസോബിയം റേഡിയോബാക്റ്റർ പിസിആർഇ 10 (0.44 സെ. മീ) എന്നിവയുടെ സംയോജനത്തിൽ ചികിത്സിച്ച സസ്യങ്ങളിൽ ഏറ്റവും കുറഞ്ഞ നിഖേദ് വലുപ്പം കണ്ടെത്തി, ഇത് രോഗകാരി നിയന്ത്രണത്തെക്കാൾ 33.33% രോഗം അടിച്ചമർത്താൻ കാരണമായി. റൈസോബിയം റേഡിയോബാക്റ്റർ പിസിആർഇ 10, പിരിഫോർമോസ്പോറ ഇൻഡിക്ക എന്നിവ സംയോജിപ്പിച്ച് ചികിത്സിച്ച കുറ്റി കുരുമുളകിന്റെ വളർച്ചയും കാൽ ചെംചീയൽ രോഗകാരിയായ കുമിളുകൾ അടിച്ചമർത്തുന്നതിലുമുള്ള തിരഞ്ഞെടുത്തു.ThesisItem Open Access Performance of long pepper (piper longum L.) on inoculation with fungal bacterial endophytes(Department of Agricultural Microbiology, college of Agriculture, Vellayani, 2020) Divya, M V; KAU; Anith, K NThe study entitled ‘Management of root-knot nematode, “Meloidogyne incognita (Kofoid and White) Chitwood in vegetable cowpea” was conducted at Department of Nematology, College of Agriculture, Vellayani, Thiruvananthapuram during 2018-2020. The objectives were to screen varieties for resistance and to evaluate efficacy of biocontrol agents, organic amendment and new nematicide fluopyram for the management of root-knot nematode in vegetable cowpea. Seven varieties of vegetable cowpea (5 KAU released and 2 local) were screened for their resistance against Meloidogyne incognita in pot culture under glass house condition. The experiment was laid out in CRD with 7 treatments and 3 replications. The results revealed that local variety collected from Kadakkal was highly resistant to root-knot nematode with root-knot index 1. The local variety performed best in reducing the multiplication of nematodes. Lowest number of egg masses 5g root-1 (2.33), eggs egg mass-1 (63.33) and nematode population 200cc soil-1 (7.33) was observed in the local variety and it showed statistically significant variation compared to the KAU released varieties. Regarding the number of nodules 5g root-1 also the Kadakkal variety showed significant superiority (22.67 nodules 5g root-1). KAU variety VS 50 was highly susceptible to M. incognita infestation with root-knot index 5. Highest number of egg masses 5g root-1(224.33) and number eggs egg mass-1 (147.00) was recorded in VS 50. Pot culture experiment was laid out in completely randomized design to standardize the dosage of fluopyram for the management of M. incognita in cowpea. The treatments were fluopyram 400 SC @ 500g a.i ha-1 as basal application, fluopyram 400 SC @ 500g a.i ha-1 as basal application + 500g a.i ha-1 25 days after first treatment, fluopyram 400 SC @ 250g ai ha-1 as basal application + 250g a.i ha-1 25 days after first treatment, fluopyram 400SC @ 250g a.i ha-1 as basal application, Untreated. All the dosages of nematicide were applied as soil drenching to the root knot nematode infected soil. Basal application of fluopyram 400 SC @ 250g a.i ha-1 was the effective dosage for managing M. incognita in vegetable cowpea. Phytotoxicity symptoms were not observed in any of the treatments. Nematode penetration in roots and life cycle completion was observed in untreated control plants. M. incognita juveniles, adult female and male were not observed in roots of fluopyram treated cowpea plants. Galls and egg masses were observed in uprooted cowpea plant roots in untreated whereas in fluopyram applied treatments it was zero. Regarding final nematode population also, no nematodes were observed in soil samples were collected from fluopyram treated plants while in untreated control plants it was 761.5. Number of rhizobium nodules was significantly lower in untreated plants (17.75) while in fluopyram treated plants it ranged from 24.25 to 27.5 in 5g roots of cowpea plants. Field experiment was conducted by using the susceptible variety (VS 50) to study the comparative effect of bio agents (Purpureocillium lilacinum) and organic amendment (neem cake) in comparison with chemicals fluopyram and carbosulfan. The experiment was laid out in RBD with 8 treatments and 3 replications. All the treatments significantly reduced nematode population in soil and root compared to untreated control. Effect of soil application of P. lilacinum (cfu 2x106 g-1) @ 10 g m-2 + neem cake @ 50 g m-2 found equally effective to basal application fluopyram 400 SC @ 250g a.i ha-1 in reducing the nematode population in soil (93.03 per cent reduction over untreated) and root (86.94 per cent reduction over untreated). Regarding yield also effect of these two treatments was statistically on par giving 53.70 to 54.63 per cent increase over untreated. Plants treated with P. lilacinum (cfu 2x106 g-1) @ 10 g m-2 + neem cake @ 50 g m-2 showed significant superiority in number of nodules (29.33) in root (5g). Results on reisolation of bioagents at the time of harvest revealed that addition of organic substrate neemcake increased the persistence of bioagent (8.33x103 cfu g soil-1) in soil. Residue of fluopyram and carbosulfan was found to be less than limit of quantification (LOQ) in cowpea pods, which were safe for consumption. From this study, it is concluded that vegetable cowpea variety Kadakkal local is resistant to M. incognita. Soil application of P. lilacinum (cfu 2x106 g-1) @ 10 g m-2 + neem cake @ 50 g m-2 can be recommended for management of M. incognita in organic cultivation of cowpea.ThesisItem Open Access Alginate based consortial formulation of native microbial fertilizers(Department of Agricultural Microbiology, College of Horticulture, Vellanikkara, 2019) Alfiya Beegum, A; KAU; Surendra Gopal, KAt present, the available biofertilizers are bulky and have short shelf life due to contamination problem. Hence, a suitable formulation needs to be developed which is less bulky and has increased shelf life. Alginate is one of the most commonly used polymers for microbial encapsulation. It is commercially extracted from seaweeds like Macrocystis pyrifera, Ascophyllum nodosum, Laminaria etc. The present study was undertaken in the Department of Agricultural Microbiology, College of Horticulture, Vellanikkara to develop an alginate based formulation of nitrogen, phosphorus, and potash biofertilizers consortia and evaluate for growth enhancement using tomato as the test crop. Five isolates each of nitrogen fixers, phosphorus and potassium solubilizers from Wayanad district were obtained from the repository maintained in the Department of Agricultural Microbiology, COH, Vellanikkara. The bacterial isolates were screened for nitrogen fixation, phosphorus and potash solubilization along with indole acetic acid production. Amount of nitrogen fixed (22.63 mg of N g -1 sucrose utilized) and indole acetic acid production (6 μg ml-1) were highest for Microbacterium arborescence. Similarly, Burkholderia cepacia recorded the highest amount of phosphorus solubilization (64.83 μg ml-1) and indole acetic acid production (8.67 μg ml-1). Among the potassium solubilizers, Acinetobacter calcoaceticus solubilized the highest amount of potassium (41.63 μg ml-1) under in vitro conditions. Microbacterium arborescence, Microbacterium testaceum and Nguyenibacter vanlangensis were selected as the three most promising nitrogen fixers. Similarly, the phosphorus solubilizers selected were Burkholderia cepacia, Bacillus subtilis (KASB5) and Bacillus subtilis (H4). The potassium solubilizers selected were Acinetobacter calcoaceticus, Burkholderia sp. and Brevibacterium sp. Compatibility studies were conducted among the selected bacterial isolates using cross streak method which showed no inhibition at the intersection of two bacterial isolates. The compatible isolate was further confirmed by dual culture method. The efficient isolates selected for consortia preparation were Microbacterium arborescence + Burkholderia cepacia + Acinetobacter calcoaceticus (N1P1K1), Microbacterium arborescence + Bacillus subtilis (KASB5) + Acinetobacter calcoaceticus (N2P2K2) and Microbacterium testaceum + Burkholderia cepacia + Burkholderia sp. (N3P3K3). In order to prepare a sterile and uniform sized alginate beads, a protocol was standardized for temperature, time and concentration of sodium alginate solution with calcium chloride solution. The optimum concentration of sodium alginate solution and temperature required for alginate beads preparation was 3% and 95 oC for 15 minutes. The diameter of alginate beads ranged between 2 mm – 2.7 mm. The rate of release of nitrogen fixers from alginate based consortia-1 during the initial 24 hours was high (41.67 x 106 cfu -1 g of beads) which reached to a population of 21 x 106 cfu -1 g of beads at 90th day. Population of nitrogen fixers, phosphorus solubilizers and potassium solubilizers decreased towards the 90th day when compared with the initial count of bacteria released from the alginate beads. A pot culture experiment using tomato as a test crop was conducted under sterile and unsterile potting mixture separately to evaluate Alginate based consortia (T1, T2 and T3), combination (T1 + T2 + T3), Talc based consortia (T5, T6 and T7) and POP (T8), Organic POP (T9) and Absolute control (T10). In sterile soil, the population of nitrogen fixers were higher for all the treatments receiving bacterial consortia. The population of P-solubilizers were higher in alginate based consortium-1 (13.0 x 106 cfu g-1) while the population of K-solubilizers were higher in treatments with combined application of alginate based consortia. Under unsterile soil, the population of nitrogen fixers were found to be higher in treatments with alginate and talc based consortia. The population of potassium solubilizers was higher in treatment with combined application of alginate based consortia. Treatments with alginate based consortium showed a higher population of phosphorus solubilizers compared with talc based consortia in unsterile soil. However, the population of N fixers, P and K solubilizers decreased with time in all treatments. Compared to initial soil status, application of alginate based bacterial consortium-1 resulted in a significant increase in available nutrient content among treatments receiving bacterial consortia in sterile soil conditions. Yield and yield attributes were higher in the alginate based bacterial consortia-1(897.0 g/plant) under sterile condition. However, yield was higher in treatment based on POP under unsterile soil conditions (845.0 g/plant). Among alginate based treatments, alginate based consortium-1 recorded a higher yield (707.33g/plant) under unsterile condition also. The present studies indicated that the alginate based consortium could be a potential microbial inoculant formulation which is less bulky, free from contamination, biodegradable and non-toxic. Encapsulation enables slow and controlled release of cells and thus, maintains a uniform bacterial population. However, further studies are required to study its shelf life, its performance under field condition before commercialization and develop a suitable protocol for large scale production.
