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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 Characterization and integrated management of Fusarium oxysporum f.sp. cubense (E.F. Smith) synder and hansen causing fusarium wilt disease of banana(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2020) Lishma, N P; KAU; Anita Cherian, KFusarium wilt of banana caused by the soil borne fungus Fusarium oxysporum f. sp. cubense (Foc) is a serious constraint to banana cultivation in Kerala. The fungal species constitute four pathogenic races, of which Race 1 is the prevalent one in our country and Race 4 is one of the emerging threats, though not reported from Kerala yet. The present study was undertaken to characterize the associated pathogenic races and to develop an integrated package for the disease management. The project initiated with purposive sampling surveys in various districts viz., Thiruvananthapuram, Ernakulam, Thrissur, Palakkad, Kozhikode and Wayanad representing different agroclimatic zones of Kerala. The per cent disease incidence (PDI) and the per cent disease severity (PDS) ranged from 1.52 to 43.65 per cent and 20.34 to 49.57 per cent. The correlation analysis of PDI with weather parameters showed a positive correlation with rainfall. However, it was negatively correlated with temperature. The study on symptoms under natural as well as artificial conditions showed characteristic external and internal symptoms. The number of days taken for complete wilting under artificial inoculation was 29.67 in Rasthali (AAB), 47.99 in Njalipoovan (AB), 31 in Kadali (AA) and 37.67 in Chenkadali (AAA). Among the thirty isolates of the Foc collected, twenty three isolates were from Rasthali variety, four isolates from Kadali, two isolates from Njalipoovan and one from Chenkadali. Studies on identification of Foc races with the differential host assay revealed that the varieties such as Cavendish (assay host to Race 4), Nendran (assay host to Race 4), Heliconia sp. (assay to Race 3) and Monthan (assay to Race 2) did not produce any type of symptoms whereas, all the isolates produced symptoms on Rasthali (assay host to Race 1) variety. A non polymerase chain reaction (PCR) based quick molecular diagnostic technique with loop mediated isothermal amplification (LAMP) assay was developed for the detection of Races of the pathogen. All isolates showed positive reaction to the LAMP assay for Race 1 and negative for Race 4. A PCR was also standardised for the confirmation of the races. It is concluded that all the isolates collected from different agroclimatic zones belonged to the Race 1 category of the pathogen only. Cultural and morphological characterization of the isolates revealed white coloured aerial mycelium with pink pigmentation and cottony and fluffy mycelial mat. The mycelial growth rate in half strength potato dextrose agar (PDA) medium ranged from 0.83 to 2.40 cm/day and the length and breadth of macroconidia and microconidia measured about 15.01 - 20.20 μm x 2.14 - 5.07 μm and 4.49 - 7.42 μm x 1.35 - 3.13 μm respectively. The inter-septal length and breadth of hyphae ranged from 16.14 to 22.94 μm and 4.22 to 6.57 μm respectively and the size of chlamydospores varied from 5.68 to 9.58 μm in diameter. The PCR based molecular characterization of isolates using ITS (internal transcribed spacer) primers produced single bands of size approximately 580 bp. In silico analysis of the sequences showed 96 to 100 per cent homology to Foc. Based on cultural, morphological and molecular characters, the pathogen was identified as Fusarium oxysporum f. sp. cubense. The screening of accessions maintained in the germplasm of Banana Research Station (BRS), Kannara was done to assess their disease resistance to Foc Race 1 and were grouped into six categories. Fifteen immune varieties viz., Attunendran, Zanzibar, Big Ebanga, Nedunendran, Nendran, BRS II, Thiruvananthapuram, Pachanadan I, Cultivar Rose, Pisang Lilin, Pisang Jari Buaya, Yangambi Km5, Grand Naine, Chinese Cavendish and Nendran Hybrid and four highly susceptible varieties viz., Cheriya Poovan, Valiya Poovan, Kadali and Rasakadali were identified. The estimation of biochemical parameters for the assessment of host plant disease resistance against Foc Race 1 revealed that the activity of total phenols and defense related enzymes was more in resistant varieties compared to susceptible varieties and the activity of reducing and non reducing sugars was more in susceptible varieties. An in vitro experiment was conducted for the evaluation of chemical fungicides, biocontrol agents and botanicals for control of the pathogen. The effective treatments from in vitro evaluation were carried over to pot culture and field experiments for the disease management. Among the various treatments, an integrated package comprising of Pseudomonas fluorescens + arbuscular mycorrhizal fungi and Trichoderma enriched cow dung + tebuconazole (T6) was proved to be the best for yield and disease management. It is concluded that the present study has enlightened our knowledge on characterization, race identification and management of Fusarium wilt pathogen infecting banana.ThesisItem Open Access Management of early blight disease of tomato (Solanum lycopersicum L.) under protected cultivation(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2020) Sumbula, V; KAU; Sainamole Kurian, PTomato (Solanum lycopersicum L.) is one of the most remunerative and widely grown vegetables all over the world. With the coordinated efforts of central and state governments, protected cultivation of tomato is now gaining popularity in Kerala. Despite being a versatile crop adapted to various agroclimatic regions and seasons, cultivation of tomato is constrained by various fungal, bacterial and viral diseases. Among the fungal diseases, early blight caused by Alternaria solani is the most common, destructive and widespread in all the tomato growing tracts. Fungicides and bioagents are commonly used to manage plant pathogens. But little is known about their effects on the non-target microbial communities that inhabit inside and outside the plant. Hence, it has become necessary to consider the effect of different fungicidal and bioagent treatments on target and non-target microbial communities while formulating disease management strategies. So, the present investigation was carried out with the objectives to formulate suitable management strategies against early blight disease of tomato under protected cultivation and to assess their impact on culturable and non-culturable microflora associated with the plant. Isolation of the pathogen from infected tomato leaf samples revealed the association of the fungus, Alternaria sp. and its pathogenicity was established by inoculating on threemonth- old tomato seedlings. Symptoms observed on leaves, shoot and fruits were almost same under both natural and artificial conditions. Cultural and morphological characters of pathogen was studied on potato dextrose agar (PDA). Initially, pathogen produced greenish brown mycelium and later turned to grey colour. Hyphae are septate and the colony has aerial topography and irregular rough growth patterns with concentric zonation. Sporulation was observed after six days of incubation and conidiophores were straight or flexuous brown to olivaceous brown in colour. The conidia are solitary straight or muriform or oblong, pale or olivaceous brown, length 40-110 μm and 7-15 μm thick with 2-8 transverse and 0-3 longitudinal septa. The cultural and morphological characters of the pathogen completely fit into the description of Alternaria solani by Alexopoulos et al. (1996). Hence, it is confirmed that the symptom observed on tomato leaves are those of early blight disease caused by A. solani. In vitro evaluation of fungicides and bioagents showed complete inhibition of the pathogen with propineb (0.1%, 0.2% & 0.3%), hexaconazole (0.05%, 0.1% & 0.15%), iprodione + carbendazim (0.1%, 0.2% & 0.3%), difenoconazole (0.075%), Trichoderma viride (KAU), T. viride (PGPM mix), T. harzianum (PGPM mix) and plant growth promoting microbial consortium (PGPM mix of KAU). Among the bacterial antagonists, Bacillus subtilis (endophyte from cocoa) showed maximum growth inhibition of the pathogen. All the three bioagents recorded earliness in seed germination and enhanced seedling vigour compared to the fungicidal treatments and control. The results of field experiment under polyhouse and rain shelter conditions showed that all the treatments are superior to control in early blight disease management, of which, spraying of iprodione + carbendazim (0.2%) and propineb (0.2%) were the best among fungicides and PGPM mix application was the most efficient among bioagents. Moreover, the highest yield was recorded from iprodione + carbendazim treated plants. Biocontrol treated plants showed better performance in overall plant vigour of which PGPM mix application was the most effective. Residue analysis showed that degradation rate of fungicides was more under polyhouse condition. Analysis of population of phylloplane and endophytic microflora proved that there was drastic reduction in microbial population after spraying with chemical fungicides whereas population increased after bioagent application. The study on survival of bioagents on tomato phylloplane revealed that both Pseudomonas fluorescens and T. viride, survived on leaf surface up to 15 days after foliar application. Analysis of fungicidal residue on tomato fruits revealed that, the degradation of fungicides was faster in polyhouse compared to rain shelter. Metagenomic analysis of microbial diversity on tomato leaves revealed that spraying of chemical fungicides reduces microbial population and diversity while bioagent application enhances the same. However, microbial community structure was changed in both cases. This study also enlightened the new mode of action for fungicides and bioagents besides their direct effect that is shifting the microbial community structure so that it provides greater resistance against the pathogen. Interestingly, metagenomic results also showed association of Cladosporium, Corynespora, Pseudocercospora along with early blight pathogen Alternaria on tomato leaves that otherwise remain undetected. Another important observation was Clostridium in tomato leaf samples except in PGPM mix treatment, suggesting the possibility of plants as alternate host for major human and animal bacterial pathogens. Hence, considering the effects of treatments on per cent disease severity both under polyhouse and rain shelter condition, residue analysis, phylloplane and endophytic microbial enumeration study and metagenomics analysis of microbial diversity, the present study recommends spraying of propineb (0.2%) as the best treatment among the tested fungicides and spraying of PGPM mix among biocontrol agents for the management of early blight disease of tomato under protected cultivation. Further system-level analysis of the complex interaction that governs outcomes among community members in the context of the plant host is required, in order to identify microbial interaction and selection processes for beneficial communities at different concentrations of fungicides and pathogen pressures.ThesisItem Open Access Deterioration of oil cake by fungi(Department of Plant Pathology, College of Agriculture, Vellayani, 1989) Naseema, A; KAU; Wilson, K IFungi causing deterioration of coconut, groundnut and sesamum oil cakes were studied. ficremonium implicatum, Asperdllus aculeatus, A. flavus, A. fumigatus, A. nlaer, A. terreus, A. versicolor, Bipolaris hawaiiensis, Curvularia clavata, Monascus ruber, Penicillium aurantioqriseum, P. Pinophilum, Pestalotiopsis palmarum, Rhizomucor £usillus and Ehizopus stolonifer were obtained from coconut oil cake. Aspergillus flavus, A. niaer, A. terreus, A. versicolor, Gliocladium sp. Penicillium pinophilum, RhizoEUS or^zae and Rhizopus stolonifer were noticed in groundnut and Aspergillus candidus, A. flavus, A. fumigatus, A. nlaer, A. tamarii, A. terreus, Curvularia clavata, Eurotium. chevalieri, F"sarium pallidoroseum, Monascus ruber, Fenicilliuiu pinophilum, Pestalotiopsls palmarum and Rhizopus or^zae in sesamum oil cake. Of these, Acremonium implicatum, Aspergillus aculeatus, A. caeslellus, A. .f"-igatus, Bipolaris hawaiiensis, Curvularia clavata, Monascus ru^, Penicillium anrantlogriseum, P. pinophilum, Pestalotiopsls palmarum and Rhizomucor pusillus from coconut oil cake, Aspergillus versicolor, Gliocladium sp., Penicillium pinophilum, Rhizopus oryzae and R. stolonifer from groundnut and Aspergillus candidus, A. fumigatus, A. tamarli, A. terreus, Curvularia clavata, Eurotium chevalieri, Fusarium pallidoroseum,Monascus ruber, Penicillium pinophilum, Pestalotiopsis palmarum and Rhizopus oryzae from sesamum oil cake have not been reported earlier. * Aspergillus flavus and A. niger were isolated from all the samples of groundnut and sesamum oil cakes. In coconut oil cake, these two fungi were present in 88.89 and 77.78 per cent of the samples. A. terreus was isolated from 66.67 per cent of groundnut and 55. 56 per cent of coconut and sesamum oil cake samples. Penicillium pinophilum was obtained from 66.67 per cent of groundnut, 44.44 per cent of sesamum and 27.78 per cent of coconut oil cake samples. Wide variation was noticed in the population of fungi present in the oil cakes collected from different regions during different periods of the year. Oil cakes collected during June-July had the highest population, of fungi. The central and the northern regions recorded higher population of fungi than the southern region. Positive and significant correlation could be obtained between weather parameters and population of fungi in different oil cakes. Maximum correlation was noticed in relation to total rainfall. Qood mycelial growth of fungi was obtained in all the oil cakes incubated at 27, 29 and 32°C. Maximum mycelial growth was noticed at 100 per cent relative humidity. This was followed by 96.1 per cent and 92.9 per cent in the descending order. The oil content of the oil cakes was considerably reduced due to the growth of all the fungi tested individually and in combination. Maximum reduction v/as noticed due to the growth of Pestalotiopsis palmarum in coconut oil cake, Rhizopus stolonifer in groundnut and Fusarium pallidorosem in sesamum oil cake. In the case of combinations, Aspergillus flavus, A. niger and Penicillium pinophilum together caused maximum reduction in oil content of coconut oil cake. In groundnut, combined growth of A. flavus, A. niger and A. terreus caused maximum reduction in oil whereas, A. niger and P. pinophilum together effected maximum reduction of oil in sesamum oil cake. Oil cakes inoculated with different fungi showed considerable reduction in total carbohydrates, crude protein, free amino nitrogen, crude fibre and ash to the extent of 6.11 to 76.95 , 4 . 28 to 68.03, 14.91 to 92.52, 1.25 to 92.55 and 0.17 to 65.16 per cent respectively. In the case of mineral nutrients like phosphorus, potassium, magnesium. calcium, copper and iron reduction ranging from 15.07 to 75.54, 23.13 to 94.41, 10.89 to 63.37, 28.78 to 90.20, 52.52 to 97.12 and 0.32 to 60.77 per cent respectively was noticed. Fourteen out of 2 0 isolates of Aspergillus flavus produced aflatoxins B^, and G2 in culture medium with maximum quantities being 1210, 1040 and 151 ppb respectively by the isolates from coconut oil cake. Eight out of 19 isolates of A. niger elaborated upto 222 ppb by the isolate from sesamum oil cake. When grown on the respective host material, A. flavus isolates from coconut oil cake produced maximum quantity of B^^, B^ and being 1517, 1092 and 272 ppb respectively. A. niger isolate from coconut oil cake produced B^^ upto 419 ppb. oil cakes treated with calcium propionate (0.6 per cent, w/w) were free from fungus growth throughout the period (180 days) of observation and showed minimum number of fungal propagules whereas, those kept as control had higher population of fungi than the treated ones, at all period.of observation. Oil cakes stored in polythene lined gunny bags had the least population of fungi, whereas those stored in ordinary gunny bag had very high population of fungi. These results revealed that fungal deterioration and spoilage of oil cakes could be prevented or reduced to the minimum by treatment with 0.6 per cent calcium propionate- and by using polythene lined gunny bags for storage arid transport.ThesisItem Open Access Fungal diseases of selected medicinal plants of Kerala(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1991) Sukumara, Varma A; KAU; ; Abi, CheeranThesisItem Open Access Study of bacterial leaf spot of betel vine- biochemical changes and control(Department of Plant Pathology, College of Agriculture, Vellayani, 1986) Koshi, Abraham; KAU; James, MathewThe bacterial leaf spot is one of the most serious diseases of betel vine in Kerala. The bacterium is one of the most serious disease of betal vine. Confidering the seriouness of the disease , studies were undertaken on the different aspects of the disease and to find out a suitable control /management practice.ThesisItem Open Access Survival of Xanthomonas campestris pv. Oryzae and its Control in Kuttanad(Department of Plant Pathology, College of Agriculture, Vellayani, 1996) Mary, C A; KAU; Sasikumar NairThe present investigation was taken up to understand the factors responsible for the recurrence of bacterial blight disease in a severe from only during the additional crop season in Kuttanad. The mode of survival of the pathogen during and in between the two major cropping seasons of Kuttanad region were also studied in detail. An extensive survey was also conducted among 115 farmers in 12 Krishibhavans of Kuttanad taluk for this purpose to collect specific informations on existing cultural practices, crop variety, nature and distribution of weed flora and self sown rice plants in and around rice fields and on wether data from June 1992 to March 1994. The efficacy of two different methods of spraying, prophylactic and curative using streptocycline, mixture of streptomycin and oxytetracycline in the proportion 1:9, Bactrinol – 100 cowdung extract on the control of bacterial blight disease was tested under field condition at Nedumudi in Kuttanad. The survey showed that there was considerable variation in the incidence of bacterial blight in Kuttanad taluk. Among the 12 Krishibhavan areas the disease incidence was maximum in Ramankari and Nedumudi and minimum in Kavalam, Kainakary and Muttar. In Neelamperoor and Thalavadi areas there was no incidence of this disease during the period of survey. Between the two major cropping seasons the disease incidence was more during the additional crop season than during Punja season. Red Triveni and Jyothy were the most popular varieties cultivated in the area and more than 50% of the farmers cultivate Red Triveni. It was observed that the variety Red Triveni as highly susceptible to bacterial blight disease. The isolate of the pathogen Xanthomonas oryzae pv. Oryzae from the rice variety Red Triveni was capable of both gelatin liquefaction and starch hydrolysis. The pathogen X. oryzae pv. oryzae was found to survive for a maximum period of 42 days in infected seed, 105 days in infected straw, 56 days in infected stubbles at room temperature, 24 days in infected stubbles under dry land condition and 14 days under wet land condition. The pathogen did not survive in soil and water. Weeds like Oryza sativa var. fatua and Paspalum conjugatum served as alternate host for the pathogen. Bacterial blight infected self sown rice plants could be seen in Kuttanad during the cropping and non cropping seasons. Due to certain specific reasons, the cultivation practices were often found to extend beyond the normal cropping seasons in the region resulting in the chances of survival of bacterial blight pathogen in the host plant itself. The specific weather conditions during the additional crop season played an important role for the severity of bacterial blight desease in this season in Kuttanad. The pathogen X. oryzae pv. oryzae was tested for sensitivity to antibiotics, Bactrinol – 100 and cowding extract under in vitro conditions. The maximum growth inhibition was obtained with oxytetracycline followed by chloramphen icol which was statistically on par with oxytetracycline. The effect of increasing concentrations of oxytetracycline in combination with streptomycin on growth of X. oryzae pv. oryzae was studied with 100, 250 and 500 ppm concentrations. The growth inhibition increased not only with the concentrations of antibiotic from 100–500 ppm but also with increasing concentration of oxytetracycline. The maximum zone of growth inhibition was obtained with 1:9 proportion of streptomycin and oxytetracycline. The five treatments selected for field evaluation trial included streptocycline at 500 ppm, streptomycin + oxytetracycline (1:9) at 250 ppm and 500 ppm, Bactrinol -100 at 500 ppm and fresh cowdung extract at 20g/1. Two different spraying methods, prophylactic and curative were evaluated in two rice varieties, T(N) 1 and jyothy. The reduction in disease index by prophylactic and curative sprayings was maximum after spraying with cowdung extract 20g/1. As regards to two methods of spraying, significant reduction in per cent disease index was obtained with curative spraying. The maximum per cent increase in grain yield over control was obtained after curative spraying with 500 ppm streptomycin and oxytetracycline mixture in jyothy followed by cowdung extract 20 g/l. In T(N) 1 and jyothy both by prophylactic and curative spraying, the thousand grain weight was maximum with cowdung extract 20 g/1. As regards to two method of spraying, significant increase in grain yield and thousand grain weight was obtained after curative spraying. In T(N) 1, both by prophylactic and curative spraying the per cent increase in straw yield was maximum with a mixture of streptomycin and oxytetracycline at 500 ppm and jyothy with cowdung extract 20g/1. In T(N)1 significant reduction in chaff per cent was recorded by prophylactic spraying while in Jyothy no significant difference was obtained by the two methods of spraying. In both these varieties the reduction in chaff per cent was maximum by spraying with cowdung extract (20g/1). It was observed that two prophylactic spraying with selected bactericidal agents, neither resulted in any significant reduction in disease index nor increase in yield as compared to curative spraying. This could be due to the fact that in Kuttanad bacterial blight disease usually occurred only around the panicle initiation stage or even later. Therefore a need based curative spraying schedule would be most effective for the control of bacterial blight disease in Kuttanad. On working out the economic benefits of controlling bacterial blight it was observed that there will be economic return only from spraying infected plants of both (T(N) 1 and jyothy with cowdung extract 20g/1. The return from plants sprayed with all other treatments in the investigation was low when compared to unsprayed control plants. Thus it will be economically advantageous to use cowdung extract to control bacterial blight of rice.ThesisItem Open Access Management of foot rot of black pepper (piper nigrum L.) with va mycorrhiza and antagonists(Department of Plant Pathology, College of Agriculture, Vellayani, 1998) Christin Robert, P; KAU; Sivaprasad, PExtensive investigation was carried out to develop a native microbial inoculant based technology involving Arbuscular Mycorrhizal Fungi (AMF) and fungal antagonists for the foot rot disease management and growth improvement of black pepper in the nursery and field. Phytophthora capsici Leonian emend A. Alizadeh and P.H. Tsao, the foot rot pathogen isolated from Peringammala, Thiruvananthapuram district was found most virulent isolate. Seven native AMF cultures and fifty fungal antagonists were isolated from Kerala soils. AMF isolates were screened in the green house for plant growth improvement and disease tolerance in comparison with identified species-Glomus fasciculatum, G.clarum and Gigaspora margarita. Of the ten AMF tested isolates Is - 6, Pi - 11, Pi - 9, G. fasciculatum and Gigaspora margarita were very effective in stimulating growth and nutrient (P, K, Ca, Mg, Cu, Fe, Mn and Zn) uptake of black pepper. Regarding the ability of AMF in reducing the foot rot incidence, Glomus fasciculatum recorded the lowest plant mortality and root rot index (53.35% and 62.50%) followed by Is - 6 (60.00% and 64.77%) and Pi - 11 (60.64% and 68.18%) as against 100 per cent mortality and 98.60 per cent root rot index noticed in control. The above five cultures were subjected for further studies. Characterisation of AMF associated with different genotypes of black pepper grown in various soil types indicated the definite influence of soil type on AMF colonization. Sandy soil (oxyaquic quartpsamment) harboured maximum root colonization while forest soil (haplic argiustoll) had the lowest. Species of Glomus particularly G. fasciculatum was the predominant AMF associated with black pepper irrespective of soil type. As an exception Acaulospora and Gigaspora species were frequently noticed in sandy soils. Based on the ability of the fungal antagonists to suppress P. capsici in vitro either through mycoparasitism, antibiosis or soil fungistasis, 24 isolates were selected for green house studies. In the further testing isolates A1, A13, A21, A22and A35 significantly reduced the foot rot infection and increased the plant growth. They showed better population build up in the soil and suppressed the P. capsici population considerably. These native antagonists were further tested in combination with selected AMF in the green house and field. Under green house condition, combination of G. fasciculatum x A1 or A21 showed significant influence on growth stimulation, while Is - 6 x A22 recorded lowest mortality of 32.90 per cent due to foot rot incidence as against 97 per cent in control. The dual inoculation of Is - 6 x A21 and Pi - 11 x A1 was highly effective in plant growth stimulation and disease suppression. Both the combination recorded less than 60 per cent infection and mortality due to the disease, while control showed 95.66 per cent infection and plant mortality. Bordeaux mixture and copper oxychloride recorded 66.67 and 59.68 per cent mortality respectively. AMF colonization and multiplication of antagonists were also favoured by dual inoculation. The potential AMF isolates Is - 6 and Pi - 11 were identified as species of Glomus while, the antagonistic isolates A1, A13, A21, A22, and A35 were confirmed as aspergillus fumigatus Fres., Fusarium oxysporum Schlecht. Ex Fr. Aspergillus sydowii (Bain. & Sart.) Thom. & Church, Trichoderma viride Pers. Ex Gray. And Gliomastix murorum (Corda) Hughes respectively. A technique for AMF inoculation to established pepper vines was developed using ‘carrier plants’. Raising sorghum with AMF inoculation around the pepper vines was found effective to achieve intense colonization in pepper roots by the introduced AMF in the field. This technique developed for the pepper vines may be tried for extending to other perennial crops for AMF inoculation. Promising AMF cultures Pi - 11, Is - 6, G. fasciculatum and antagonists Aspergillus fumigatus, A. sydowii, Trichoderma viride were further tested on eight year old established pepper vines following ‘carrier plant’ based AMF inoculation and cowdung - neem cake based antagonist inoculation. The treatment Pi - 11 x A. Sydowii was most effective with no symptom development, followed by Is- 6 x T. Viride or A. sydowii with disease score of 2.0 as against 7.0 recorded for control. The disease score for bordeaux mixture and copper oxychloride application was 3.5 and 3 respectively. Neem cake-cowdung food base was highly favourable for multiplication and activity of fungal antagonists. The amino acids, total sugar and reducing sugar and total phenols and orthodihydroxy phenol content and activity of cellulose and chitinase were influenced by AMF colonization particularly by Is - 6 and Pi - 11. The positive change could be related with the relative disease tolerance recorded for various AMF isolates. The development of native AMF and antagonists through extensive testing in the green house and field and also the technology of AMF inoculation for established pepper vines are the first record of work.ThesisItem Open Access Effectiveness of soil solarization for the control of soft rot disease in ginger(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1996) Vilasini, T N; KAU; Peethambran, C KThe effectiveness of soil solarisation for the control of soft rot disease in ginger was studied at the College of Horticulture, Vellanikkara, Thrissur during March 1992 to December 1993. The beds were inoculated with Pythium aphanidermatum, five days before the solarisation. Transparent, 150 guage polyethylene sheets were used for solarizing the beds. Maximum soil temperatures recorded were 63.00, 59.00 and 46.50 at 5, 10 and 15 cm depths in solarized soil, while, that in non-solarized soils were 49.50, 43.00 and 40.00C, respectively, at 5,10 and 15 cm depths. Temperature in the solarized soil at 5 cm depth was above 50.00 C for the entire solarisation period and above 55.00 C for 38 days, while, at 10 cm depth the temperature was above 50.00 C for 35 days and above 55.00 for five days. The soil temperature at 15 cm depth never reached 50.00 C during the solarisation period. Based on the soil and air temperature recorded, two simple regression equations at 5 and 10 cm depths, one simple equation at 15 cm depth and one multiple regression equation at 10 cm depth were developed for predicting soil temperature under polyethylene mulch. Rate of germination in ginger was enhanced by solarisation. Significant effect of solarisation was observed in controlling the pre and post-emergence rotting in ginger. Increasing the period of solarisation from 30 to 45 days did not result in a corresponding reduction in the pre-emergence rotting. Trichoderma incorporated neem cake amended 30 day solarized treatment was highly effective and recorded cent percent control of the soft rot disease, while, maximum disease incidence (90.67%) was in Trichoderma incorporated neem leaves amended 45 days solarized plots. Reduction in Pythium population ranging from 79.49 to 99.1 per cent was observed in solarized plots immediately after the removal of polyethylene sheets. Solarization reduced the total fungal, bacterial, actinomycetal and Pseudomonas sp. population in the field. Plants grown in solarized plots showed better colonization of VAM and Azospirillum. Significant reduction in the nematode population was recorded by solarisation. Solarization had a profound suppressive effect on the weed population and it lasted till harvest. Solarization effect was more pronounced in dicots. Eventhough, solarisation substantially reduced weed population, its effect was less in the edges. Bulbostylis barbata, Cynodon dactylon and Cyperus rotundus survived the solarisation effect. Increased growth response of ginger plants was observed as a result of solarization. Growth parameters like height, number of leaves/plant, number of tillers, number of roots, leaf length, leaf breadth, fresh weight of shoots and rhizomes were influenced by solarisation. Significant increase in the yield was obtained through solarisation. Trichoderma incorporated and neem cake amended 30 days solarized treatment gave the maximum yield/plant (623.23 g) and also per plot yield (10159.57 g), which was 5361 per cent more than that of control. Availability of nitrogen, phosphorus and potassium was improved by solarisation. The initial cost of solarization is comparatively high, an amount of Rs. 52,500/- is required for solarizing one hectare of ginger field. An additional profit generated from this technique was Rs. 40,136/ha for 30 days solarisation.ThesisItem Open Access Symbiosis of rhizobium and VA mycorrhiza in subabul(Department of Plant Pathology, College of Agriculture, Vellayani, 1989) Rajendran Pillai, M V; KAU; Sasi Kumar NairA survey was conducted at 17 locations in four districts of Kerala for natural nodulation and VA mycorrhizal infection in subabul. The survey revealed that natural nodulation and VA mycorrhizal infection were poor compared to inoculated plants. When all the 17 isolates of rhizobia and four cultures of VA mycorrhizal fungus were tested for effectiveness, the rhizobial isolate R8 and V AM fungus M2 were emerged as most efficient rhizobial and mycorrhizal cultures respectively. An in vitro study conducted revealed that in an acid PH of 6, the rhizobial isolate R8 survived better than other cultures. At pH 8, growth of another isolate R5 was found maximum. However, in an in vivo study, there was not much significance for the soil pH ranging from 6 to 7.1 in influencing various biometric parameters of subabul. In both the pH of 6 and 7.1, the performance of rhizobial isolate R5 and mycorrhizal culture M2 was best. Serological studies revealed that the exotic strains R18 R20 and and isolate from Mimosa indica had serological similarities with the best selected local isolate R8. Fine structure studies of nodules clearly showed the morphological differences between the uninfected nodular tissues and the infected central nodular tissue. The rhizobial infection transformed the normal cells into irregularly shaped cells within which numerous rhizobial cells were visible. In another observation, it was found that subabul plants starts to form nodules only from 15 days of sowing. There- after, the nodule number increased steadily attaining the peak at 70 days of growth and then remained more or less steady. Among various methods of inoculation of the microsymbionts tested, inoculation of both the microsymbionts at the time of sowing in polybag was found good for the better establishment of the plants in the field. In a field study, it was found that inoculation of the local isolate of Rhizobium R8 and mycorrhizal fungus M2 had great influence in increasing all the growth parameters. Standard mycorrhizal culture and local isolate performed equally well. Maximum forage yield was obtained when plants were inoculated with the selected local rhizobial isolate R8 and mycorrhizal fungus M2. Maximum mycorrhizal infection was also seen in the same treatment. Dual inoculation also had significant influence in increasing the leaf protein content. An important observation was that both rhizobial and mycorrhizal inoculation reduced the mimosine content of leaves. However, fertilizer nitrogen increased mimosine content. In short, dual inoculation by Rhizobium and VA mycorrhiza was found necessary for better establishment, growth and low mimosine content of subabul.
