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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.
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ThesisItem Open Access Evaluation of native rhizosphere microflora for plant growth promotion and management of fusarium yellows in ginger(Department of Agricultural Microbiology, College of Horticulture, Vellanikkara, 2016) Rekha, K G; KAU; Surendra Gopal, KA study was undertaken on “Evaluation of native rhizosphere microflora for plant growth promotion and management of Fusarium yellows in ginger”. The main objectives were to enhance the growth and yield of ginger using native beneficial microorganisms isolated from wayanad district and to manage Fusarium yellows disease in ginger by using antagonistic microorganisms. Rhizosphere soils were collected from ten different locations of healthy and diseased ginger fields of Wayanad district. The predominant beneficial microorganisms namely nitrogen fixing bacteria, phosphate solubilizing bacteria, Bacillus sp., Pseudomonas fluorescens, Streptomyces sp., and Trichoderma sp. were isolated. The highest population of nitrogen fixers (1.4x104 cfu/g), fluorescent pseudomonads (9x104 cfu/g), and Trichoderma sp. (6x103 cfu/g) were obtained from Pulpalli location. Phosphate solubilizing bacteria (9x103 cfu/g) and Streptomyces sp. (6x104cfu/g) were highest in Kappikunnu and maximum population of Bacillus sp. (2.3x104 cfu/g) was recorded in Mayilumpadi. The isolates were screened for plant growth promotion and antagonistic activity under in vitro condition. Maximum nitrogen fixation was recorded in NFMh isolate (0.43 mg/g of sucrose utilized) among nitrogen fixers. Highest IAA (35.02 μg/ ml), HCN and siderophore production were recorded by NFAh (nitrogen fixer) isolate. Among the phosphate solubilizers, highest P- solubilization (450.00%) was by PSBAh isolate where as, IAA (33.07 μg/ ml) and HCN was shown by PSBMh isolate. Among the isolates of Bacillus sp. The maximum P- solubilization index (182.99%) was recorded by BsAh isolate and the least (137.43%) by BsKUh isolate. Highest IAA (14.54 μg/ml) was produced by BsMh isolate (Mayilumpadi) and the least (12.92 μg/ml) by BsAh isolate (Appade). Out of the ten isolates tested for HCN production, only three BsMh, BsKuh and BsPTd isolate resulted moderate level of HCN production. Only one isolates, BsMh positive for siderophore production. All the seven isolates of fluorescent pseudomonads the highest (241.57%) psolubilization was in PfMh isolate and lowest (190.11%) by the isolate PfKh. Highest IAA production was (16.75 μg/ml) by the isolate PfKh from Kappikunnu and the lowest (12.13 μg/ml) by PfPh isolate. Hydrogen cyanide production of all the isolates were tested and that isolates PfPh and PfKUh produced highest HCN under in vitro screening. Siderophore production was produced only by three isolates PfKh, PfMh, and PfPh. Among the eight isolates of Streptomyces sp. the maximum P- solubilization index (176.99%) was recorded by StrAh isolate and the least (153.76%) by StrPh isolate. Highest IAA (11.63 μg/ml) was produced by StrMh isolate (Mayilumpadi) and the least (10.41 μg/ml) by StrKUh isolate (Kurumankotta). Two isolates StrMh and StrPh resulted moderate level of HCN production. Four isolates StrMh, StrPh, StrAh and StrAd isolates resulted siderophore production. StrPh (Pulpalli) isolate resulted excellent siderophore production. All the isolates of Trichoderma sp. did not solubilized phosphorus and IAA under in vitro screening Two isolates TrPh and TrKUh produced moderate HCN under in vitro screening. Siderophore production was produced only by three isolates TrKh, TrMh, and TrAh. Selected isolates of Bacillus sp., Pseudomonas fluorescens, Streptomyces sp., Trichoderma sp., were tested for their antagonistic activity against the major soil borne pathogens of ginger viz., Fusarium oxysporum, Pythium aphanidermatum, Rhizoctonia solani and Ralstonia solanacearum under in vitro condition. The isolate BsAh showed maximum antagonistic activity against F. oxysporum (64.08 per cent) and P. aphanidermatum (15. 09 per cent) where as, BsKh isolate was antagonistic against R. solani (47.09 per cent) and BsMh isolate showed 43.81per cent inhibition against R. solanacearum. Among Pseudomonas fluorescens, PfKh showed 59.43 per cent inhibition against F. oxysporum where as PfAh isolate recorded 33.71 per cent inhibition against P. aphanidermatum, 27.20 per cent aginst R. solani and PfPh isolate showed 31.32 per cent inhibition against R. solanacearum. Among the isolates of Streptomyces sp., StrPh isolate recorded maximum inhibition (67.78 per cent) against F. oxysporum, 43.11 per cent inhibition against R. solani and 34.23 per cent against R. solanacearum. TrAh isolate (Trichoderma sp.,) showed highest (78.93 per cent) inhibition against F. oxysporum, 51.30 per cent inhibition against P. aphanidermatum and 43.27 per cent against R. solani. However, TrMh isolate shown 15.96 per cent inhibition against R. solanacearum. Three most efficient isolates of nitrogen fixers (NFMh, NFPh, NFKh), phosphate solubilizing bacteria (PSBPh, PSBKh, PSBAh), Bacillus sp., (BSMh, BSAh, BSKUh), fluorescent pseudomonads (PFKh, PFPh, PFAh), Streptomyces sp., (StrPh, StrMh, StrKh) and Trichoderma sp., (TrAh, TrKUh, TrPh) obtained under in vitro studies were further screened under pot culture studies. Among the isolates PSBPh (T4) was found to be the most efficient in enhancing the growth and yield of ginger where as the isolate TrKUh (T11) was the most efficient isolate for the management of Fusarium yellows disease. These two isolates were identified as Burkholderia cepacia (PSBPh) and Trichoderma harzianum (TrKUh). The present study clearly showed that Burkholderia cepacia (PSBPh) and Trichoderma harzianum (TrKUh) were effective for plant growth promotion and management of Fusarium yellows in ginger respectively. However, these isolates have to be evaluated for efficiency under field conditionThesisItem Open Access Functional diversity of beneficial microorganisms from the rhizosphere of black pepper in Wayanad(Department of agricultural microbiology, College of Horticulture,Vellanikkara, 2015) Athira, P S; KAU; Girija, DBlack pepper (Piper nigrum L.) is a perennial, woody and flowering climber belonging to family Piperaceae. It is one of the important spice crops which provides major source of income and employment for rural households in Kerala. Wayanad dominated in pepper farming in the state about 20 years ago. Annual production of pepper was 40,000 tonnes in the mid-1980s, which comprised about half of India’s total pepper production. But recently, the production has declined drastically due to the infestation of pests and diseases. Foot rot caused by Phytophthora capsici and yellowing of black pepper are the major diseases devastating most of the plantations in Wayanad. However, some of the plants in the disease affected areas remain healthy which could be due to inherent activity of native rhizosphere microflora. The present study focused on assessing the functional diversity of beneficial microorganisms which could possibly be exploited for the benefit of plant growth. Four healthy gardens, four gardens each affected by foot rot and yellowing were selected for sample collection. Rhizosphere soil samples were collected from five healthy vines in each garden. Population of beneficial microbes in the rhizosphere soils of healthy and disease affected gardens were compared. In general, rhizosphere soil from healthy gardens recorded higher population of bacteria, fungi, phosphate solubilizers and fluorescent pseudomonads. A total of 207 isolates (including 112 bacteria, 32 actinomycetes and 63 fungi) were purified and maintained to study their plant growth promoting and antagonistic activities. Maximum IAA production (292.50 μg ml-1) was recorded by HPLBC-6 followed by HABC-3 (46.43 μg ml-1). The isolate HPLPSB-3 was the most efficient P solubiliser (162.7 μg ml-1) followed by HPLF-5 (161.3 μg ml-1). The isolate YPTN- 3 fixed maximum amount of nitrogen (46.92 mg of N g-1 of sucrose) followed by HVKN-6 (32.62 mg of N g-1 of sucrose). From the invitroexperiment, two most promising isolates each of IAA producers, phosphate solubilizers and nitrogen fixers were selected for preliminary screening for growth promotion on blackpepper cuttings. The isolate HPLPSB-3 (P solubiliser) recorded maximum sprouting, vine length, number of leaves, number of roots and roots fresh weight underinplanta screening for plant growth promotion. However, maximum root length was observed in HPLBC-6 (IAA producer). All the isolates were screened in vitro for their antagonistic activity against foot rot pathogen Phytophthora capsici. Among the bacteria, isolate HPLPSB-6 recorded maximum inhibition (69.27 %) of the pathogen. Among the actinomycetes, HVZACT-1 recorded maximum mycelial inhibiton of 66.66 %. Among the fungal isolates screened, maximum inhibition (75.17 %) was recorded by the isolate FPRF-3. The three most promising PGPM selected from preliminary in planta screening and three antagonists from in vitro screening were further tested for their efficiency in controlling foot rot disease in blackpepper nursery. Minimum disease incidence (6.23%) and severity (4.00 %) were observed in isolate FPRF-3. This was followed by actinomycete HVZACT-1 with disease incidence of 13.20 % and severity of 8.00 %. Maximum disease incidence and severity were observed in control with pathogen alone. In addition to biocontrol activity, FPRF-3 also improved plant growth parameters such as length of vine, number of leaves and roots. The selected growth promoting isolates HPLPSB-3, HPLBC-6 and YPTN-3 were identified as Acinetobacter grimontii, Providencia sp. and Paenibacillus sp. The three selected antagonists HPLPSB-6, HVZACT-1 and FPRF-3 were identified as Paenibacillus polymyxa, Streptomyces termitum and Trichoderma viride respectively. Based on in planta evaluation, Acinetobacter grimontii was considered as the best PGPM and Trichoderma viridethe most promosing antagonist against P. capsici. These isolates could be further exploited for improving the growth and managing foot rot disease, after validation under field conditions. The compatibility of PGPM with antagonists and chemical fungicides may also be evaluated.This is the first report of antagonistic activity of the actinomycete S. termitum against P. capsici causing foot rot disease in blackpepper.ThesisItem Open Access Management of bacterial wilt disease of tomato by the root endophytic fungus piriformospora indica, rhizobacteria and bacterial endophytes(Department of Agricultural Microbiology, College of Agriculture, Vellayani,Thiruvananthapuram, 2018) Athira, S; KAU; Anith, K NThe study entitled “Management of bacterial wilt disease of tomato by the root endophytic fungus Piriformospora indica, rhizobacteria and bacterial endophytes” was conducted during 2016-2018 at Department of Agricultural Microbiology, College of Agriculture, Vellayani with the objective of assessing the potential of root endophytic fungus Piriformospora indica, plant growth-promoting rhizobacteria and bacterial endophytes in suppressing bacterial wilt incidence in tomato. The bacterial wilt pathogen, Ralstonia solanacearum was isolated from infected tomato plants on Semi selective medium from South Africa (SMSA). Koch’s postulates were proved by artificial inoculation of tomato seedlings. A functional relationship between population and optical density of the broth culture was worked out and was used for determining the inoculum density for challenge inoculation in the biocontrol experiment. In vitro antagonistic interaction between the bioagents and the pathogen was worked out both by direct and indirect assays. In all direct assays which involved cross streak plating, agar plug diffusion technique, disc diffusion and spot on lawn method, it was found that Bacillus amyloliquefaciens VLY24, Bacillus velezensis PCSE10 and Streptomyces leeuwenhoekii KBT004 exhibited antagonism against Ralstonia solanacearum. Indirect antagonism was checked by agar well diffusion and disc diffusion methods using culture filtrate. Out of the eight bacterial bioagents tested, only two i.e., Bacillus velezensis PCSE10 and Bacillus amyloliquefaciensVLY24 had inhibitory effect on the pathogen. Dual culture plate assay on PDA has shown that three bacterial bioagents, Rhizobium radiobacter PCRE10, Bacillus megaterium NAT001 and Streptomyces leeuwenhoekii KBT004 were compatible with Piriformospora indica. However, when the compatible bacteria were co-cultured in a single fermentor system along with Piriformospora indica it was observed that Bacillus megaterium NAT001 failed to grow along with the fungal endophyte. Suppression of bacterial wilt incidence by the individual and combined application of bacterial bioagents and fungal endophytes were tested with the wilt susceptible tomato variety Naveen (Indo-American hybrid seeds Pvt. Ltd, Bengaluru) and the moderately tolerant KAU variety Vellayani Vijay. Bioagents were applied during the nursery production of seedlings and the 21 days old seedlings were transplanted to pots filled with unsterile garden soil. Challenge inoculation with the pathogen was done five days after transplanting by drenching the pots with 10 ml each of the bacterial suspension (107cfu/ml). The disease incidence was scored at weekly intervals for 21 days. When the bioagents were tested individually for the suppression of bacterial wilt incidence in the hybrid variety Naveen, maximum disease suppression was observed in plants treated with Rhizobium radiobacter PCRE10 (15 percent) after 21 days. The disease suppressive ability of Bacillus velezensis PCSE10 (25 percent) was also significantly superior to all other treatments. Selection of bacterial bioagents for combined application with Piriformospora indica was done based on compatibility with the fungal endophyte and inhibitory action against Ralstonia solanacearum. Combined application of the fungal endophyte and Bacillus amyloliquefaciens VLY24 suppressed the wilt incidence to the highest extent (40 percent). When bacterial wilt suppression in Vellayani Vijay was tested by the individual application of bacterial bioagents, maximum disease suppression was recorded in plants treated with Streptomyces leeuwenhoekii KBT004 (30 percent), when observed 21 days after challenge inoculation. The combination of Piriformospora indica with Rhizobium radiobacter PCRE10 (50 percent) and Bacillus velezensis PCSE10 (50 percent) showed significantly lower disease incidence compared to the rest of the treatments. In the plant growth promotion experiment done with the variety Vellayani Vijay in the nursery stage, maximum plant height was observed in plants treated with Rhizobium radiobacter PCRE10 (14.49cm). However, those plants treated with Bacillus pumilus VLY17 had the highest number of leaves per plant (4.58). Combined inoculation of Piriformospora indica and Bacillus amyloliquefaciens VLY24 resulted in improved shoot fresh weight (2.08 g per plant) which was on a par with the plants treated with Bacillus velezensis PCSE10 (1.95 g plant-1). However, shoot weight on dry weight basis was the maximum for plants treated with Bacillus velezensis PCSE10 (122.55 mg plant-1) which was at par with those treated with combination of Piriformospora indica and Bacillus amyloliquefaciens VLY24 (104.78 mg plant-1). The present study revealed that biological management of bacterial wilt in tomato could be a feasible strategy under controlled conditions. The same has to be validated under field conditions before making any recommendations.ThesisItem Open Access Development of inoculant cultures of zinc solubilizing microorganisms(Department of Agricultural Microbiology, Vellayani, 2016) Aathira S Kumar; KAU; Anith, K NThe study entitled “Development of inoculant cultures of zinc solubilising microorganisms” was conducted at College of Agriculture, Vellayani during the period 2014 - 2016 with the objective of isolation, characterization and evaluation of zinc solubilising microorganisms from soils of Kerala and to develop inoculant culture of the best zinc solubilising isolate. Microorganisms capable of solubilising zinc were isolated from Agroecological units 20, 21 (Wayanad) and 8 (Thiruvananthapuram) by serial dilution technique on Bunt and Rovira medium containing 0.1% insoluble zinc oxide. Ten isolates of bacteria capable of solubilising insoluble forms of zinc (zinc oxide) were obtained and allotted code numbers from ZSB-1 to ZSB-10. These were subjected to plate assay and broth assay in media supplemented with 0.1 per cent insoluble forms of zinc as zinc oxide or zinc phosphate. After three days of incubation of test plates, all the ten isolates solubilised zinc and produced clearing zone around the colonies on solid media. The size of the solubilisation zone ranged from 8.67 mm to13.33 mm in zinc oxide and from 1.00 mm to 5.33 mm in zinc phosphate incorporated medium. In broth culture, maximum solubilisation of zinc in both sources was observed on 30th day in the range of 35.91 ppm to 104.08 ppm in zinc oxide supplemented medium and 1.38 ppm to 4.15 ppm in zinc phosphate supplemented medium. The isolate ZSB – 4 showed maximum solubilisation of zinc in plate assay and broth assay. For soil incubation study, the isolate with maximum zinc solubilisation (ZSB – 4) was inoculated in zinc deficient soils and analysed for the soil chemical parameters and population dynamics of the bacterial isolate for a period of three months. The treatments were designed as T1 and T2 with Zn at two levels as ZnO, T3 with Zn solubilising culture alone @ 2 kg ha-1, T4 and T5 with Zn solubilising culture @ 2 kg ha-1 supplemented with Zn at two levels as ZnO and T6, the absolute control had no insoluble zinc supplementation and inoculation with the bacterial isolate. The isolate ZSB – 4 significantly increased the available zinc content in soil from 0.55 ppm to 9.47 ppm in treatment T4 (ZSB – 4 @ 2 kg ha-1 + zinc oxide @ 1 kg ha-1) during the incubation period. The same treatment registered the highest mean value for available phosphorus content, 12.09 kg ha-1 and 12.26 kg ha-1 respectively for the 2nd and 3rd month. There was an increase in oxidisable organic carbon content in the 3rd month for treatments T4 (1.44%), T5 (1.43%) and T3 (1.38%) and it was maximum in T4 which was statistically on par with T3 and T5. On the 3rd month, there was a decrease in the available boron content in soil for the treatments T3 (0.30 ppm) and T5 (0.34 ppm) when compared with previous months and the treatment T4 (0.33) maintained the level of boron. The total zinc content of the soil ranged from 0.05 % to 0.08 % during the entire three months and the mean values had no significant difference among treatments. The maximum colony count of 9.3 x 103 cfu g-1 of soil was recorded in the treatment T4 during the 3rd month which was on par with T5 (9.1 x 103 cfu g-1) and T3 (8.8 x 103 cfu g-1). The best isolate ZSB – 4 was subjected to molecular characterization and it was revealed that the organism is Bacillus cereus. Different carrier materials like talc, lignite, vermiculite, vermicompost and perlite were used in the present study to assess survival of ZSB – 4. Among the different carriers tested, the talc powder supported the maximum population of 3.9 x 108 cfu g-1 during the 3rd month. Based on the results of present study it can be concluded that application of talc based formulation of the zinc solubilising bacteria ZSB – 4 (Bacillus cereus) @ 2 kg ha-1along with zinc oxide @ 1 kg ha-1 was found to increase zinc content in soil after incubation. Based on the survival of the isolates in different carriers for the development of inoculant cultures, talc was found to be most suitable carrier for the formulated product.ThesisItem Open Access Assessment of soil temperature and soil parameters on the population and functional efficiency of pseudomonas fluorescens in the rhizosphere of Pokkali rice (Oryza Sative L.)(Department of Agricultural Microbiology, College of Agriculture, Vellayani, 2018) Reshma Francis; KAU; Surendra Gopal, KPokkali is a umque variety of rice that is cultivated organically in coastal wetlands of Kerala. Pokkali fields are situated close to the sea and therefore prone to flooding and salinity. Pokkali rice has enormous potential for tolerating most of the abiotic stresses. It is the only economic crop which can be grown in waterlogged environment while tolerating salinity. The present study on “Assessment of soil temperature and soil parameters on the population and functional efficiency of Pseudomonas fluorescens in the rhizosphere of Pokkali rice (Oryza sativa L.)”, was conducted in Rice Research Station, Vyttila, under Kerala Agricultural University during 2016 to 2018. Two plots (40 m2) were used for the study. One of the plots was maintained as control (without application of Pseudomonas fluorescens) and another plot with rice was treated with P. fluorescens. P. fluorescens (KAU) was applied as seed treatment (10g kg-1) just before sowing and soil application (2.5 kg ha-1) at 1 week after dismantling. The main objectives were to study the effect of soil temperature and soil parameters on the population and functional efficiency of P. fluorescens / fluorescent Pseudomonas in Pokkali rice. The rhizosphere soils of Pokkali rice were collected at monthly interval from June, 2017 to October, 2017. The population of fluorescent Pseudomonas sp. in the rhizosphere soils of Pokkali rice were recorded at monthly interval. The population was absent before the start of the experiment in treated plot. However, the highest population 3.3x102 cfu g-l) was recorded at 90 DAS (August, 2017). However, the lowest population was recorded at 60 DAS (July, 2017). The population was not found at 30 DAS (June, 2017), 120 DAS (September, 2017) and 150 DAS (October, 2017). In the case of control plot, population of fluorescent Pseudomonas was absent before the start of experiment. At 30 DAS (June, 2017) population of fluorescent Pseudomonas was 3.3 x 102 cfu g-1. However, no fluorescent Pseudomonas were found at 60 DAS (July, 2017), 90 DAS (August, 2017), 120 DAS (September, 2017) and 150 DAS (October, 2017). Out of the six isolates (VPJU, VPJL, VPAU1, VPAU2, VPAU3 and VPAU4) of fluorescent Pseudomonas obtained, all the isolates produced IAA and ammonia with varied intensity. Three isolates (VPAU1, VPAU3 and VPAU4) produced HCN and none of the isolates showed siderophore production. The correlation studies between soil temperature, soil pH, EC and C02 evolution with population, revealed that the population of fluorescent Pseudomonas was affected by soil pH and soil EC. However, soil temperature and C02 evolution did not affect the population of fluorescent Pseudomonas. The functional efficiency of the fluorescent Pseudomonas were correlated with soil temperature, soil pH, EC and C02 evolution It was found that soil temperature, soil pH, EC and C02 evolution did not affect the functional efficiency of fluorescent Pseudomonas. All the six isolates obtained m the study were identified and confirmed through 168 rDNA sequencing. The isolates VPAJU, VPAU1 and VPAU2 were identified as Pseudomonas sp. and VPAJL, VPAU3 and VPAU4 isolates were found to be Pseudomonas aeruginosa. The present studies indicated that the inoculated P.fluorescens did not survive in Pokkali fields. The population of fluorescent Pseudomonas showed negative correlation with soil pH and EC. However, soil temperature and C02 evolution did not had any effect on population. The functional efficiency of fluorescent Pseudomonas was not affected by soil temperature, soil pH, EC and C02 evolution. However, further studies on influence of soil edaphic factors and weather variables on host plant and P. fluorescens needs to be studied and develop a suitable PGPR for Pokkali rice.ThesisItem Open Access Standardization of liquid formulation of PGPR MIX-1 and its evaluation for plant growth promotion in amaranthus(amaranthus tricolor L.)(Department of Agricultural Microbiology,College of Agriculture, Vellayani,Thiruvananthapuram, 2018) Gokul, K Gopi; KAU; Meenakumari, K SThe study entitled “Standardization of liquid formulation of PGPR mix–I and its evaluation for plant growth promotion in Amaranthus (Amaranthus tricolor L.)” was conducted in the Department of Agricultural Microbiology, College of Agriculture, Vellayani during the period 2016-2018. The main objectives of the study were standardization of liquid formulation of PGPR mix–I and its evaluation for plant growth promotion along with saving of chemical fertilizers in amaranthus. The component cultures of PGPR mix-I, Azospirillum lipoferum, Azotobacter chroococcum, Bacillus megaterium and Bacillus sporothermodurans were procured from the Department of Agricultural Microbiology, College of Agriculture, Vellayani. All the isolates produced significant quantity of IAA under in vitro conditions. The nitrogen (N) fixers, Azospirillum lipoferum and Azotobacter chroococcum produced 40.31 and 36.43 ppm of IAA respectively, whereas Bacillus megaterium and Bacillus sporothermodurans produced 1.28 ppm and 3.36 ppm of IAA respectively. The in vitro estimation of N fixation by N fixing organisms namely, Azospirillum lipoferum and Azotobacter chroococcum recorded a significant quantity of 21 and 14 mg N g-1 of carbon source respectively. Quantitative assessment of solubilization of phosphorus (P) by Bacillus megaterium present in PGPR mix–I under in vitro conditions recorded 69.36 ppm, whereas qualitative assessment recorded a clearing zone of 8 mm and 12 mm diameter in NBRIP and Pikovaskayaˈs medium respectively. Similarly, in vitro assessment of K solubilization by Bacillus sporothermodurans recorded 12.18 ppm of potassium (K) and a clearing zone of 18 mm diameter in Glucose Yeast Agar medium. Morphological and biochemical characterization of the isolates supported the genus level identification of the isolates. An experiment was carried out to standardize the protocol for the preparation of liquid formulation of PGPR mix–I in completely randomized design with different treatments such as 2% Glycerol, 2% Polyvinylpyrrolidone (PVP), 15mM Trehalose, 1% Glycerol + 1% PVP, Glycerol (2%) + Trehalose (1%) + Yeast extract (1%) + PVP (1%) + Proline (1%) and control without any additives in four replications. Talc based formulation was kept as a standard. In spite of inconsistent viable count recorded in different treatments till eighth month, from ninth month onwards, formulation amended with 15mM Trehalose exhibited maximum viable count until fourteenth month. A significant decline of total viable population in talc based formulation was observed in each month compared to 15mM Trehalose amended formulation. Based on the population study, 15mM Trehalose amended formulation was adjudged as the best liquid biofertilizer formulation. Even after fourteenth month significant population was observed in 15mM Trehalose amended formulation and hence the shelf life studies of the same have to be continued. A pot culture experiment was conducted in completely randomized design using sterilized soil under glass house conditions to test the efficacy of the best treatment ( liquid formulation amended with 15mM Trehalose ) with amaranthus as the test crop The seven treatments included 100% NPK as per KAU recommendation as chemical fertilizer alone, talc based or liquid formulation of PGPR mix–I each alone and with 100% and 50% NPK, control with additives without PGPR microorganisms and absolute control in three replications. Roots of seedlings were dipped in 2 per cent of the freshly prepared liquid formulation at the time of transplanting and 50 ml of 2 per cent liquid was drenched in the soil in each pot two weeks after transplanting. The results indicated that the treatment T6- liquid formulation of PGPR mix–I+ 100% NPK recorded, maximum plant height of 37.54 cm, leaf number of 44.44 and leaf area index of 4.97 at harvest, but was on par with T3- talc based formulation of PGPR mix–I+ 100% NPK. The treatment T6 also recorded maximum fresh and dry weight of shoot (55.41 and 4.97 g plant-1 respectively) and fresh and dry weight of root (6.6 and 0.56 g plant-1 respectively). However, the treatment T6 was found to be on par with T3 in these characters also. But T6 recorded the least oxalate content of 0.39 per cent as well. The treatment liquid formulation of PGPR mix–I + 50% NPK (T7) was found to be statistically on par with chemical fertilizer @ 100% NPK (T1) in parameters such as plant height, number of leaves, leaf area index, fresh and dry weight of shoot and root and oxalate content. Application of treatments had significant effect on the soil available NPK content. Analysis of rhizosphere population after application of PGPR mix-I revealed successful colonization of organisms of PGPR mix-I in the rhizosphere of amaranthus. The present investigation could standardize the protocol for liquid formulation of PGPR mix-I with 15 mM Trehalose as the best amendment. The study revealed that liquid formulation of PGPR mix–I is equally effective as talc based formulation of PGPR mix–I along with 100% NPK chemical fertilizers in enhancing yield and other biometric parameters of amaranthus. Compared to talc based formulation, the liquid formulation of PGPR mix–I showed higher shelf life beyond fourteenth month. The study also indicated that liquid formulation of PGPR mix–I + 50% NPK as chemical fertilizers was on par with chemical fertilizer @ 100% NPK and hence a saving of 50 per cent of chemical fertilizers could be advocated after confirmatory field trials.ThesisItem Open Access Evaluation of biofilm based microbial antagonists for the management of soil borne diseases and growth promotion in cowpea (Vigna unguiculata L. Walp)(Department of Agricultural Microbiology, College of Horticulture, Vellanikkara, 2018) Vinay Kumar, B; KAU; Surendra Gopal, KThe biocontrol agents play an important role in the plant disease management and growth promotion. They are eco-friendly and low cost agricultural inputs. One of the major constraints in the use of biocontrol agents, is the survivability of inoculated cultures till the end of the crop period. So, there is a need to enhance the survivability of the biocontrol agents for the management of soil borne pathogens and growth promotion. Trichoderma and Bacillus sp. are two well-known biocontrol agents for plant disease management and growth promotion. Cowpea is one of the most popular, protein rich legume crop of Kerala. One of the major constraints in the cowpea production is the diseases like collar- rot (Rhizoctonia solani) and root rot (Pythium aphanidermatum) which have become a serious threat. Since, no studies have been conducted in Kerala on the biofilm based inoculants, an attempt was made to increase the survivability of Trichoderma and Bacillus through biofilm based inoculants for the management of two major soil borne diseases and growth promotion in cowpea. Rhizosphere soil samples were collected from ten different cowpea growing areas of Thrissur district. The maximum population of Trichoderma sp. (4.8 × 103 cfu g-1) and Bacillus sp. (4.48 × 105 cfu g-1) were recorded in Chellakara and Mala, respectively. A total of nine Trichoderma sp. and five Bacillus sp. were obtained. They were screened for plant growth promoting and antagonistic activities. Among Trichoderma sp., maximum IAA production (24.03 μg ml-1) was recorded by TCK- 2 (Chalakudy) followed by TML (Mala) (14.77 μg ml-1). TML (Mala) isolate was the most efficient P solubilizer (147.2 μg/ml). Among Bacillus sp., maximum IAA production (6.20 μg ml-1) and maximum P solubilization (151.3 μg ml-1) were recorded by BCH (Chellakara) isolate. Among Trichoderma sp., TCH-1 (Chellakara) and TMT (Mttathur) were positive for HCN production and TCH-1, TMT, TMS, TPZ and TCK-1 were positive for ammonia production. Among Bacillus sp., BCH (Chellakara) and BMT (Mattathur) were positive for HCN production and all five isolates (BCH, BML, BMS, BPN and BMT) were positive for ammonia production. Both Trichoderma sp. and Bacillus sp. were screened in vitro for their antagonistic activity against Rhizoctonia solani and Pythium aphanidermatum. Among Trichoderma sp., TCH-1 (Chellakara) isolate recorded maximum inhibition (51.1%) against Rhizoctonia solani and Pythium aphanidermatum (57.7%). Bacillus sp. isolates were screened for biofilm production and highest biofilm production was recorded by BCH (Chellakara) (0.060) followed by BPN (Pazhayanur) (0.058) isolates. Based on the PGPR traits, per cent inhibition and biofilm production under in vitro, three most promising Trichoderma sp. (TCH, TMT, TPZ) and Bacillus sp. (BCH, BPN, BML) were subjected for mutual compatibility studies. All the selected Trichoderma sp. and Bacillus sp. were mutually compatible with each other. The isolates of TCH (Chellakara) + BCH (Chellakara), TPZ (Pazhayanur) + BPN (Pazhayanur) and TMT (Mattathur) + BML (Mala) were selected for the biofilm based inoculant production. Among the different carrier materials for biofilm based inoculant production talc powder was the most promising carrier material due to highest population of isolates at 90 DAI. Biofilm based inoculants were evaluated under pot culture for the management of collar rot (Rhizoctonia solani) and root rot (Pythium aphanidermatum) in cowpea under two separate experiments. Based on the biometric parameters, collar rot and root rot disease management and yield parameters, biofilm based formulation of TCH (Chellakara)+BCH (Chellakara) (T2) was the most promising treatment for the management of collar rot disease and growth promotion in cowpea, which was on par with the PGPR Mix- II (T9). Population of inoculated Trichoderma sp., Bacillus sp. and Rhizobium sp. indicated declining trend till the final harvest of the crop. The population decreased from 108 cfu ml-1 to 104 cfu ml-1. However, biofilm based inoculant showed highest population of Trichoderma sp. and Bacillus sp. at the time of harvest. The three best promising Bacillus sp. isolates were identified through 16S rRNA sequencing and identified BCH isolate as Bacillus subtilis, BPN as Bacillus velezensis and BML as Bacillus megaterium.ThesisItem Open Access Isolation and characterization of pink pigmented facultative methylotrophs (PPFMs) associated with paddy(Department of Agricultural Microbiology, College of Agriculture, Vellayani, 2018) Nysanth, N S; KAU; Meenakumari, K SThe study entitled “Isolation and characterization of Pink Pigmented Facultative Methylotrophs (PPFMs) associated with paddy” was conducted in the Department of Agricultural Microbiology, College of Agriculture, Vellayani during the period 2015-2017. The main objectives of the study were isolation, characterization and evaluation of Pink-Pigmented Facultative Methylotrophs (PPFMs) associated with paddy for antagonistic efficiency, seed germination, seedling growth and yield of paddy. . The pink pigmented facultative methylobacteria (PPFM) were isolated from phyllosphere of paddy collected from different locations of Kerala by leaf imprint method on Ammonium Mineral Salt (AMS) agar medium supplemented with 0.5% methanol and cycloheximide. Forty six isolates were obtained from different locations and code numbers were allotted for each of the isolate. They were tentatively identified as PPFMs based on the characteristic pink pigmented colonies on AMS agar supplemented with 0.5% methanol as sole source of carbon and energy. The product developed by Tamil Nadu Agricultural University was taken as the reference culture. Indole Acetic Acid production by the different isolates of PPFM showed wide variations ranging from 9.27 to 68.65 μg mL-1 of culture filtrate. Maximum IAA production of 68.65μg mL-1 of culture filtrate was recorded by PPFM35. The reference culture produced 57.39 μg mL-1 of IAA. All the isolates were found to produce carotenoid pigment in varied quantity ranging from 0.07 to 1.74 μg mL-1. Among these isolates, the highest carotenoid production was recorded in PPFM16 (1.74 μg mL-1). The reference culture recorded a total carotenoid production of 0.64 μg mL-1. The antagonistic efficiency of all forty seven PPFM isolates including reference culture was assessed against two important fungal pathogens of paddy namely, Rhizoctonia solani, Pyricularia oryzae and one bacterial pathogen, Xanthomonas oryzae pv. oryzae following dual culture method. Six out of forty seven isolates tested inhibited Rhizoctonia solani. The results revealed that the isolate PPFM 10 exhibited the maximum zone of inhibition (ZOI) of 12.72 mm. The reference culture inhibited Rhizoctonia solani and produced a ZOI of 9.07mm. Four out of forty seven isolates tested showed antagonistic activity against Pyricularia oryzae with PPFM24 producing the maximum zone of inhibition of 10.00 mm. Four out of forty seven isolates tested inhibited Xanthomonas oryzae pv. oryzae and PPFM5 produced the maximum ZOI of 9.80 mm diameter. In the study on the effect of PPFM isolates on seed germination and seedling growth both treated and uninoculated control seeds germinated on the second day of seed treatment. Maximum germination percentage of 100 was recorded in seeds treated with PPFM35. Treatment with PPFM30 recorded the maximum shoot length of 26.38 cm and maximum root length of 24.20 cm was obtained in seeds treated with PPFM22 and same isolate recorded the highest seedling vigour index of 4756.35 over the control (3037.91). The root shoot ratio of seedlings showed significant increase when seeds were treated with PPFM isolates. Maximum root shoot ratio of 0.62 was observed when seeds were treated with PPFM26 and PPFM35 compared to control (0.33). A pot culture experiment was conducted using variety Jyothi (Ptb-39)) in completely randomized design using wetland soil. Seedlings were dipped in 2 per cent of liquid culture of the PPFM isolates before transplanting. One per cent foliar spray of the liquid culture of respective isolates was given 15 and 30 days after transplanting. Appropriate control treatments and replications were maintained. Application of PPFM isolates significantly increased growth and biomass production. Also the yield of paddy was significantly increased. PPFM11 recorded the highest grain yield of 46.30 g hill-1 whereas the control recorded a grain yield of 33.65 g hill-1 only. The reference culture recorded a grain yield of 38.40 g hill-1. Physiological characterization of plants revealed significant influence of PPFM isolates on chlorophyll content, cell membrane stability and proline content of the plant compared to untreated plants. The isolates PPFM11, PPFM16, PPF19, PPFM22 and PPFM35 were adjudged as superior isolates based on maximum germination percentage, seedling vigour index, growth promotion efficacy and grain yield of paddy. These five isolates were identified as Methylobacterium spp. based on morphological, biochemical and molecular characteristics.ThesisItem Open Access Impact of weather variables on the functional efficiency of beneficial microflora in the rhizosphere of black pepper (piper nigrum L.)(Department of Agricultural Microbiology, College of Horticulture, Vellanikkara, 2017) Manju Mohan, E; KAU; Surendra Gopal, KBlack pepper has been reported to be the most vulnerable spice crop to climate change. The beneficial microorganisms in the rhizosphere of black pepper can reduce the impact of abiotic stress due to changes in the weather variables. However, the soil microbial community are also influenced by changes in weather and microclimatic parameters. A study was undertaken on the “Impact of weather variables on the functional efficiency of beneficial microflora in the rhizosphere of black pepper”. The main objectives were to study the effect of weather and microclimatic parameters on the population and functional efficiency of beneficial microflora namely; Azospirillum, phosphate solubilizing bacteria (PSB), Pseudomonas fluorescens and Trichoderma sp. The rhizosphere soil samples from black pepper were collected at monthly interval for a period of one year from Pepper Unit, Kerala Agricultural University (KAU), Vellanikkara. The selected beneficial microorganisms were enumerated and in vitro screening was done at monthly interval for IAA, ammonia, HCN, siderophore production, phosphate solubilization and antagonistic activity against Phytophthora capsici. Simultaneously, the weather and microclimatic parameters were also recorded. The Azospirillum and PSB were not obtained throughout the study period from July, 2015 to June, 2016. The population of fluorescent pseudomonads was highest in September, 2015 and was absent in March, 2016 and April, 2016. Trichoderma sp. recorded the highest population in July, 2015 and lowest in June, 2016. A total of 31 isolates of fluorescent pseudomonads and 3 isolates of Trichoderma sp. were obtained during the entire study period. Out of 31 isolates of fluorescent pseudomonads, 29 isolates produced ammonia with different concentrations. Fifteen isolates produced HCN and only ten isolates showed siderophore production as their antagonistic mechanism. Only 5 isolates were phosphate solubilizers and 4 isolates were antagonistic to Phytophthora capsici. However, in the case of Trichoderma sp. two isolates produced ammonia, one isolate was HCN producer, two produced siderophore and two isolates showed antagonistic activity against Phytophthora capsici. Considering the correlation studies between weather, microclimatic parameters and population of isolates obtained, it was found that the population of fluorescent pseudomonads were positively correlated with rainfall and soil moisture whereas negatively correlated with air temperature, sunshine hours and soil temperature. However, the population of Trichoderma sp. was positively correlated with rainfall, relative humidity and soil moisture whereas it was negatively correlated with air temperature, sunshine hours and soil temperature. The study indicated that rainfall (200 to 500 mm) and soil moisture (15 to 20%) favoured fluorescent pseudomonads and Trichoderma population. The functional efficiency of the isolates were also correlated with the weather and microclimatic parameters. In case of fluorescent pseudomonads, the weather and microclimatic parameters had no significant effect on its ammonia and HCN production. However, significant effect on the siderophore production was noticed. In the case of Trichoderma, weather and microclimatic parameters had no significant effect on ammonia, HCN and siderophore production. The present studies clearly indicated that the weather and microclimatic parameters affected the siderophore production in the case of fluorescent pseudomonads but, there was no effect on functional efficiency of Trichoderma sp. However, mitigation strategies have to be studied in the case of fluorescent pseudomonads to overcome the effect of weather and microclimatic variables on functional efficiency.
