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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 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 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.ThesisItem Open Access Evaluation of abiotic stress tolernant PGPR and trichoderma sp. for growth and disease management in black pepper (piper nigrum L.)(Department of Agricultural Microbiology, College of Horticulture, Vellanikkara, 2017) Sri Vithya, R; KAU; Surendra Gopal, KA study was conducted on the “Evaluation of abiotic stress tolerant PGPR and Trichoderma sp. for growth and disease management in black pepper (Piper nigrum L.)” at the Department of Agricultural Microbiology, College of Horticulture, Vellanikkara during May 2015 to July 2016. The objective of the study were to screen Azospirillum sp., Micrococcus sp., Burkholderia sp., Pseudomonas fluorescens and Trichoderma sp., for abiotic stress tolerance under in vitro and also evaluate the abiotic stress tolerant isolates for growth and disease management in black pepper under stress (polyhouse) and without stress (natural) conditions. Rhizosphere soil samples were collected from ten different black pepper growing areas of Thrissur district for isolation of Azospirillum sp., Micrococcus sp., Burkholderia sp., Pseudomonas fluorescens and Trichoderma sp. The isolates obtained were screened for PGPR activities, abiotic stress tolerance and screening for antagonistic activity against P. capsici. The most promising isolate from each type of microorganism were selected for pot culture experiment to evaluate the selected abiotic stress tolerant isolates for growth promotion and disease management in black pepper. Azopsirillum sp. was not recorded in the black pepper rhizosphere soil collected from Thrissur district. In the case of Micrococcus sp., the highest population was recorded in Pazhayannur (45×104 cfu g-1). In the case of Burkholderia sp., was highest in Kannara (116.5×104 cfu g-1). In the case of Fluorescent pseudomonads, the highest population was recorded in Chellakkara (55×104 cfu g-1). And Trichoderma sp., was highest in Mupliyam (96.5×103 cfu g-1). A total of 34 obtained different microbial isolates were screened for PGPR activities (IAA production, % P - solubilisation, Ammonia production and HCN production) and abiotic stress tolerance (temperature tolerance 280C, 370C, 410C and 500C, acidity tolerance and drought tolerance). Based on the PGPR activities and abiotic stress tolerance, the most promising isolates selected for pot culture experiment were Micrococcus sp. - VKM isolate (410C, pH 5.5 and -0.15 M Pa osmotic stress) Burkholderia sp. - PAB isolate (410C, pH 5.5 and -0.15 M Pa osmotic stress), fluorescent pseudomonads - PAP isolate (410C, pH 5.5 and -0.15 M Pa osmotic stress) and Trichoderma sp. - CKT isolate (370C, pH 5.5 and -0.15 M Pa osmotic stress). The maximum Per cent inhibition (64.75 %) was recorded in the case of Burkholderia sp. (KKB) and in the case Trichoderma sp. the maximum per cent inhibition (66.95 %) was recorded with CKT isolate. The isolates were further screened under pot culture experiment. There were two pot culture experiments with polyhouse condition (with elevated temperature as stress) and natural condition (without stress). Under polyhouse condition (with elevated temperature as stress), T5 (Trichoderma sp. - CKT isolate) and T6 was the most efficient isolates for enhancing the growth of black pepper. However, T4 (Pseudomonas fluorescens - PAP isolate) and T5 (Trichoderma sp. - CKT isolate) were the most promising treatments for Phytophthora disease management. Under natural condition (without stress), T8 (PGPR Mix - II - KAU ref. culture) and T4 (Pseudomonas fluorescens - PAP isolate) were the most efficient isolates for enhancing the growth of black pepper under natural condition (without stress). However, T3 (Burkholderia sp. - PAB isolate), T4 (Pseudomonas fluorescens - PAP isolate) and T5 (Trichoderma sp. - CKT isolate) were the most promising isolates for Phytophthora disease management. Among the isolates obtained in the present studies, the most promising abiotic stress tolerant isolate for growth promotion and disease management in black pepper under polyhouse condition was Trichoderma harzianum (T5 - CKT isolate), whereas Pseudomonas fluorescens (T4 - PAP isolate) was the most promising abiotic stress tolerant isolate under natural conditions. Most promising abiotic stress tolerant isolate for abiotic stress tolerance, growth promotion and Phytophthora disease management in black pepper nursery under both polyhouse and natural conditions was Trichoderma harzianum (T5 - CKT isolate). However, further studies are needed to confirm the results.ThesisItem Open Access Biocontrol potential of plant associated bacteria from piper spp. against phytophthora capsici infecting black pepper(Department of Agricultural Microbiology, College of Agriculture, Vellayani, 2017) Nadiya Kollakkodan; KAU; Anith, K NThe study entitled “Biocontrol potential of plant associated bacteria from Piper spp. against Phytophthora capsici infecting black pepper” was conducted at the Department of Agricultural Microbiology, College of Agriculture, Vellayani and Coconut Research Station, Balaramapuram during 2015-2017 with the objective to study the antagonistic effect of plant associated bacteria from Piper colubrinum and Piper nigrum, and their potential for the biological control of Phytophthora capsici induced foliar infection in black pepper in the nursery. Plant associated bacteria were isolated from phylloplane, stem surface and within the leaves, stem and roots of P. colubrinum and P. nigrum on different bacteriological media. A total of 70 isolates were obtained, out of which 39 were from P. colubrinum and 31 from P. nigrum. The isolates were grouped based on cultural and morphological characters. In the initial in vitro screening using dual culture plate assay, it was found that out of the 70 isolates obtained, 16 isolates showed inhibitory effect against P. capsici. The results revealed that the isolates PCSE8 and PCSE10 had the maximum zone of inhibition. The dual culture plate assay was followed by a detached leaf assay using the 16 isolates showing inhibition. It was found that minimum lesion size was observed in leaves sprayed with isolate PCSE10 which caused 79.02% disease suppression over the control, which was on par with leaves sprayed with PCSE5. Biochemical characterization of the selected isolates were carried out using biochemical kits and a tentative genus level identification was done. Molecular level characterization was done and the plant associated bacteria from Piper spp. having biocontrol potential against P. capsici were identified as Burkholderia cenocepacia, Acinetobacter sp, Staphylococcus epidermidis, Streptomyces deccanensis, Bacillus sp, Rhizobium sp, Pantoea dispersa, Bacillus velezensis, Enterobacter sp, Acinetobacter baumannii and Bacillus subtilis. A greenhouse experiment was carried out at Coconut Research Station, Balaramapuram, to study the effect of selected isolates on plant growth promotion and suppression of P. capsici induced foliar infection in the black pepper var. Karimunda. Suppression of foliar infection 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 Rhizobium sp PCRE10 (1.18 cm) which caused 75.05% disease suppression over the pathogen control with the lowest disease index of 0.2. The isolate B. velezensis PCSE10 resulted in 53.69% disease suppression over pathogen control with a disease index of 0.32. The plant growth promotion aspects of the plant associated bacteria were studied by analysing the biometric characters of rooted cuttings of black pepper var. Karimunda at 70 DAP. Maximum leaf number was observed in plants treated with B. velezensis PCSE10 (2.25). The treatments had significant effect on the rooting of the cuttings. The highest root number was observed in plants treated with isolate Rhizobium sp PCRE10 (12.33) followed by S. deccanensis PCRE1 (10.92). A similar trend was observed in root fresh weight and root dry weight. The shoot dry weight was highest in plants treated with B. velezensis PCSE10 followed by plants treated with B. velezensis PCSE8. The study revealed that wild relative of black pepper, P. colubrinum is a good source for isolation of antagonistic bacteria against P. capsici. Bacterization with endophytes improved the plant growth characteristics and helped in better establishment of plants. Treatment with plant associated bacteria from P. colubrinum and P. nigrum suppressed the development of foliar infection of P. capsici. The endophytes of P. colubrinum, Rhizobium sp PCRE10 and B. velezensis PCSE10 were selected as best candidates when both disease suppression and plant growth promotion were considered..ThesisItem Open Access Evaluation of bacillus thuringiensis isolates against diaphania indica (saund.) (Lepidoptera:pyralidae)(Department of Agricultural Microbiology, College of Horticulture, Vellanikkara, 2017) Janish Rose, Jacob; KAU; Girija, DChemical pesticides provide significant benefit by controlling pests of agricultural crops. However, their use has increased at an alarming rate, along with proportionate increase in their adverse effect on the environment. In recent years, several insects have developed resistance towards a few pesticides due to their indiscriminate use. Several microbial agents have been used as an alternative for chemical pesticides and Bacillus thuringiensis is one among them. B. thuringiensis is a sporulating, Gram positive, facultative anaerobic soil bacterium, capable of synthesizing δ-endotoxins or Cry proteins during sporulation. Due to the insecticidal properties of these proteins, the bacterium is used against insect species of the orders Lepidoptera, Coleoptera and Diptera. More than 500 isolates of B. thuringiensis obtained from the Western Ghats of Kerala, in a DBT funded project, are being maintained in the repository of the Department of Agricultural Microbiology, College of Horticulture, Thrissur. Several microbial inoculants such as Pseudomonas fluorescens, Trichoderma viride, Beauvaria bassiana, Lecanicillium lecanii have been developed by Kerala Agricultural University but there is no formulation of B. thuringiensis. A study was conducted to develop a commercial formulation of B. thuringiensis and to evaluate its bio-efficacy against the pumpkin caterpillar, Diaphania indica (Saund.). Twenty native isolates with cent per cent mortality in previous studies were selected from the repository of the Department of Agricultural Microbiology. Morphological, biochemical and molecular characterisation of these native B. thuringiensis were carried out. The isolates showed only very slight variations in their cultural characteristics. Colonies appeared circular, creamy white with entire to undulate margin and flat elevation. The isolates showed positive reaction to starch and esculin hydrolysis, sucrose fermentation test and negative to Voges-Proskauer test. The isolates were screened for the presence of lepidopteran specific insecticidal genes, using PCR. Among the 20 native B. thuringiensis isolates, seven isolates yielded cry1 gene amplicons. None of the isolates produced cry2 and cry9 amplicons. The cry1 amplicons were further sequenced and when subjected to Blastn analysis showed homology towards cry1, cry1A, cry1Aa and cry1Ac. All the isolates have shown identity in the range of 93-96 per cent to the known cry1 genes. Thus, the presence of cry1 gene was confirmed. Based on the abundance of crystal protein and cry1 gene, three native isolates (KAU-11, KAU-474 and KAU-2189) were further selected for laboratory bioassay against the lepidopteran pest, D. indica. Among the native isolates, KAU-2189 showed highest per cent morality and was further selected for liquid formulation studies. Suitability of three media (soy flour broth, coconut water broth and T3 broth) was assessed based on the population and spore count at 0 h, 72 h and 96 h after inoculation. Coconut water yielded higher population than the standard medium (T3 broth). Spore count of B. thuringiensis in coconut water and T3 were statistically on par. Thus, coconut water served as the best among the tested substrates for B. thuringiensis production and this was further used for the liquid formulation. Bio-efficacy of the liquid formulation was evaluated in pot culture experiment against D. indica using little gourd (Coccinia indica) as the test crop. Btk (ABTEC), a commercial formulation was used as standard. The higher per cent mortality was recorded for the formulations containing KAU-2189 in coconut water broth and HD-1 in coconut water broth and both were statistically on par with each other. Minimum leaf damage was also recorded in treatments with these formulations and was statistically on par with each other. Shelf life studies of liquid formulations indicated that both population and spore count decreased from fourth month onwards. The study revealed that the native isolates have the potential to be developed into a biopesticide. Coconut water could be used as an ingredient for low cost liquid formulation. Further evaluation under field conditions is required to confirm the efficiency of KAU-2189 as a biopesticide.ThesisItem Open Access Metagenomic analysis of bacterial diversity in the rhizosphere of arecanut palms affected by yellowing in Wayanad(Department of Agricultural Microbiology, College of Horticulture, Vellanikkara, 2017) mahesh Mohan; KAU; Girija, DThe study entitled “Effect of growth retardants on growth and yield of African marigold (Tagetes erecta L.)” was conducted at College of Agriculture, Padannakkad during 2015-2017 with the objective to assess the response of marigold in terms of growth, yield and carotenoid content as influenced by foliar application of growth retardants Alar and Cycocel. The experiment was laid out in split plot design during two seasons viz., monsoon and pre-monsoon. The data was subjected to statistical analysis to find out the effect of growth retardants on different parameters. The experimental material comprised of Pusa Narangi Gainda and Maxima Yellow F1 varieties of African marigold and their response to growth retardants was evaluated with treatments viz., C1 : Alar 500 ppm, C2 : Alar 1000 ppm, C3 : Alar 1500 ppm, C4 : Cycocel 1000 ppm, C5 : Cycocel 1500 ppm, C6 : Cycocel 2000 ppm and C7 : Water spray (control). The analysis of data regarding different plant characters revealed that the varieties and growth retardants resulted in significant differences with vegetative, floral and yield characters and pigment contents in flowers. Growth retardants significantly influenced plant height, plant spread, number of branches, internodal length, and stem girth, number of flowers, flower yield and carotenoid content. There was no significant difference noticed on days to first flowering, days to 50 % flowering, flower length, pedicel length, flower diameter and flower weight. The effects of growth retardants on leaf area, SCMR, total biomass, crop duration, flowering duration and post-harvest longevity varied with seasons. On comparing the two varieties during two seasons, Maxima Yellow F1 performed better for most of the growth and floral characters and recorded highest flower yield in monsoon season. From economic point of view, Maxima Yellow F1 can be recommended during monsoon season in Kerala to meet the high demand of flowers during Onam. Among the growth retardants, Cycocel 1000 ppm can be recommended for better growth, higher yield and carotenoid content in Pusa Narangi Gainda and Maxima Yellow F1 varieties of African marigold during monsoon season and pre-monsoon seasons.ThesisItem Open Access Exploration of native mineral phosphate solubilizing microorganisms as biofertilizer for the acidic soils of Kerala(Department of Agricultural Microbiology, College of Horticulture, Vellanikkara, 2016) Saranya, K S; KAU; Girija, DA study was undertaken on ‘Exploration of native mineral phosphate solubilizing microorganisms as biofertilizer for the acidic soils of Kerala’. The main objective was to exploit native microorganisms with mineral phosphate solubilization and plant growth promoting activities for the acidic soils of Kerala.
