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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 Strain improvement of oyster mushrooms- pleurotus cystidiosus O.K. Mill and pleurotus opuntiae (Durieu and LEV.) SACC.(Department of Plant Pathology, College of Agriculture, Vellayani, 2018) Krishnapriya, P J; KAU; Geetha, DThe present study entitled “Strain improvement of oyster mushrooms: Pleurotus cystidiosus O.K.Mill and Pleurotus opuntiae (Durieu and Lev.) Sacc.” was carried out in College of Agriculture, Vellayani during 2015-2018, with the objective to standardize the techniques for production of oyster mushrooms: P. cystidiosus and P. opuntiae; and to study their morphological, physiological and cultural characteristics as well as nutritional and organoleptic qualities; and to undertake genetic improvement by protoplast fusion. The mushrooms were collected from two locations of Thiruvananthapuram and three fast growing isolates of Pleurotus spp. viz., PC2 (Vellayani), PNC1 (Chirayinkeezhu) and PO1 (Vellayani) were selected for the study. These isolates were identified as P. cystidiosus subsp. abalonus, P. cystidiosus and P. opuntiae using internal transcribed spacer (ITS) primers and subsequent sequencing; and registered at Genbank database with accession numbers KY214254, KY887023 and KY214255 respectively. The fast growing isolates of P. cystidiosus (coremial), P. cystidiosus (non-coremial) and P. opuntiae recorded maximum growth on PDPA amended with one per cent yeast under dark condition. The optimum temperatures for the growth were 30 0C, 25 to 30 0C and 25 0C respectively whereas, the optimum pH were 8, 8 and 7 to 8 respectively. Studies with different substrates and amendments for spawn production revealed that sorghum with one per cent yeast was the best for P. cystidiosus (coremial) and P. opuntiae whereas, paddy grains with one per cent yeast for P. cystidiosus (non-coremial). Experiments with different substrates and amendments for mushroom production revealed that rubber wood sawdust sprayed with 2.5 per cent of 1 M potassium dihydrogen phosphate recorded the maximum BE for P. cystidiosus (non-coremial) (192.76 per cent). P. opuntiae recorded the maximum BE in rubber wood sawdust amended either with 4 per cent neem cake (91.38 per cent) or wheat bran (91.37 per cent). Major insect pests observed in the beds of Pleurotus spp. were phorid flies, spring tails, black ants and staphylinid beetles. The competitor moulds observed were different species of Coprinus, Aspergillus, Penicillium and Trichoderma. Sporocarps soaked in one per cent CA for 15 minutes followed by mechanical drying and powdering was the best post harvest treatment for both P. cystidiosus (non-coremial) and P. opuntiae. Mycelium of P. cystidiosus (coremial) showed black coremial structures, representing its asexual stage (Antromycopsis broussonetiae Pat. & Trab.). The coremia comprised of elliptical (16.31 µm x 7.48 µm) and round conidia (8.06 to 8.49 µm). The black colour of coremia was due to melanin which was extracted (255.56 mg l-1) and characterized. The performance of long duration P. cystidiosus (non-coremial) and short duration P. opuntiae was compared with two ruling mushrooms of Kerala viz., long duration P. florida (Mont.) Singer and short duration P. eous (Berk.) Sacc. The study revealed that P. cystidiosus (non-coremial) and P. opuntiae showed higher BE compared to P. florida and P. eous, respectively. P. cystidiosus (non-coremial) recorded maximum moisture (94.05 per cent), starch (200.55 mg g-1), protein (30.2 mg g-1), fat (4.25 per cent), antioxidants (485.45 μg equivalent gram of ascorbic acid-1), beta-carotene (25.69 µg 100 mg-1), polyphenols (7.55 mg g-1) and energy (359.45 Kcal) compared to other Pleurotus spp. Sensory evaluation of mushroom products made from the species of Pleurotus was done and masala curry prepared from P. cystidiosus (non-coremial) scored the maximum value for overall acceptability. Shelf life of P. cystidiosus (non-coremial) was higher (5 days) compared to P. opuntiae, P. florida and P. eous (3 days each) in perforated poly propylene covers stored under refrigeration. Vanillin (0.05 per cent) and carbendazim (1 mM) were selected as dual biochemical markers for the PEG mediated protoplast fusion. Three days old P. cystidiosus (non-coremial) and four days old P. opuntiae recorded the maximum protoplast yield at five and four hours after incubation respectively with 0.6 M KCl and 30 mg ml-1 of enzyme consortium. Eight fusant lines with varied mycelial characters were obtained. Among fusants, F6 and F8 did not segregate in the second generation whereas, F4 segregated. F6 and F8 recorded higher BE of 168.05 and 99.95 per cent respectively compared to the parental lines and other fusants. Sporocarp of F6 and F8 was morphologically similar to P. cystidiosus (non-coremial) and P. opuntiae respectively; and F8 also exhibited low temperature adaptability. The present investigation indicated the exploitability of two promising isolates viz. P. opuntiae for tropical areas and P. cystidiosus (non-coremial) for cooler regions of Kerala using locally available materials and the standardized cultivation practices. The present study also standardized the protoplast fusion technique between P. cystidiosus (non-coremial) and P. opuntiae; and two fusant lines (F6 and F8) recorded higher BE which can be used for future breeding programmes.ThesisItem Open Access Integrated management of viral diseases of bittergourd (momordica charantia L.)(Department of Plant Pathology, College of Agriculture, Vellayani, 2018) Radhika, N S; KAU; Umamaheswaran, KThe present research work entitled ‘Integrated management of viral diseases of bitter gourd (Momordica charantia L.) was carried out in the College of Agriculture, Vellayani during 2014-2017, with the objectives to study the occurrence and distribution of viruses in bitter gourd in Thiruvananthapuram, Idukki and Palakkad, immunomolecular characterization of the viruses, and screening of antiviral chemicals, antiviral principles of animal, plant and microbial origin for the management of the disease. In the suvey conducted at five locations in Thiruvanaanthapuram district, Pappanchani area recorded highest incidence of viral disease (60%) while highest Vulnerability Index (V.I) was recorded from Vellayani (56.00). In Idukki district, six major bitter gourd cultivating areas were surveyed among which Rajakumary area recorded the highest disease incidence (100%) and V.I (82.00). In Palakkad district, five locations were surveyed, among which panackatri and Thekkepotta recorded highest disease incidence of 88% and highest V.I (69.00). The major insects associated with the crop were whitefly (Bemisia tabaci (Genadius) with an incidence of 10-25%, aphids (Aphis gossypii glover) with an incidence of 10-40%, Jassids (Empoasca (Empoasca) motti Pruthi) with an incidence of 10-30% and mites with an incidence of 10-50%. Phyllody and little leaf symtoms (20% incidence) were also recorded in bittetgourd form Rajakumary and Rajakkad areas in Idukki. Flat limb and multiple proliferation of shoot tip were observed at many fields in Idukki. Symptoms associated with the disease include yellow mottle, mosaic,blistering, leaf curl and reduction in leaf size. Yellow mosaic and blistering is seen in severe infection finally leading to stunting of the plant, reduced flowering an fruiting and hairyness on stem. Mechanical transmission of the virus on Datura stramonium produced yellow lacal lesions indicating the presenceof Bean Golden mosaic virus (Begomo) in the infected leaf extract. This leaf extract also produced local lesions on othe indicator hosts like Chenopodium amaranticolor and Gomphrena globosa indicating the presence of Cucumber mosaic virus (CMV) or Potato virus Y (PVY). The viruses were transmitted by whiteflies (20%) and aphids (30%) from infected bittetgourd plants to healthy seedlings. Whiteflies (Bemisia tabaci Gennadius)) and aphids (Aphis gossypii Glover) are the vectors of the respective viruses Wedge grafting diseases scion on to 3-5 leaf stage healthy seedling of bittergourd produced symptoms of infection within ten days. KAU varieties Preethi and Priyanka were found to be susceptible to infection with preethi expressing a V.I of 70.80 and Priyanka expressing a V.I of 62.50 respectively. Ensyme linked immunosorbent assay (ELISA) and Dot immunobinding assay (DIBA) revealed the presence of three viruses belonging to Begomo, CMV and PVY group causing an mixed infection in bittergourd. The presence of all the three viruses were also confirmed in electron micrograph, Begomovirus as twin particles of size 18-20 X 30nm,CMVas single particles of 18nm and PVY as lonog flexuous rod of size 750nm. PCR amplification of coat protein gene (cp gene) of virus isolates from all the three districts yielded an amplicon of size approximately equal to 570 bp. Idukki and Palakkad isolates showed 94% identity to Tomato leaf Curl Virus isolate TNUDU BGI Coat Protein (AVI) gene while Trivandrum isolate showed 95% identity to Tomato leaf Curl Virus isolate TNPDU BG4 Coat Protein (AV1) gene . Phylogenetic tree constructed using multiple sequence alignment programme showed close relation between Begomo viruses identified in bittergourd from different districts. Studies on defense related enzymes such as peroxidase (PO), polyphenol oxidase (PPO) and phenyl alanine ammonialyase PAL) showed significant activity of PO and PPO in diseased plants than in healthy plants and the activity was on par in healthy and diseased for PAL. Protien profile of healthy and diseased at different days after virus inoculation through grafting indicated the production of novel proteins in diseased. There was no difference in the native profile of peroxidase in healthy and diseased at 15 days after virus inoculation. An additional isozyme band with a Rm value of 0.5 was observed in diseased at 45 days after virus inoculation. Management of the disease with antiviral chemicals and antiviral principles of plant, animal and microbial origin was undertaken as pot culture studies with pre and post inoculation of treatments. Twelve treatments with three replications each were laid out in completely randomized design for the evaluation. The treatments included Aspirin at two levels of 100 and 150 ppm, Salicylic acid (SA) at two levels of 100 and 150 ppm and Acibenzolar S methyl (ASM) at 50 and 75 ppm concentration, and two commercial formulations viz., Perfect and virus –Ex at 0.5 and 1.0 ml concentrations. The treatments were applied three times at 10 days interval. Pre application of thrice sprapying of Acibenzolar S methyl (ASM), 75 ppm concentration (V.I-35.00) at ten days interval was statistically significant over other treatments followed by ASM-50 ppm (V.I-41.33). Post application of antiviral chemicals also showed a statistically significant effect of three times spraying ASM-50 ppm(V.I-25.00) at ten days interval followed by spraying of Virus Ex 1ml L-1 (VThe best eight treatments with control was laid out as Randomised Block Design at the Instructional Farm, College of Agriculture, Vellayani during February to May 2017 as a field trial to study the effect of treatments on natural incidence of the viruses in the susceptible variety Preethi. The treatment, three sprays of ASM-50 ppm (V.I-28.33) at ten days interval ws on par with buttermilk (Three times dilution of curd) (V.I-39.16). Yield was also significantly high in ASM-50 ppm (437g plant-1) followed by Pseudomonas fluorescens talc based formulation (2%) (233 g plant-1)among the treatments.ThesisItem Open Access Etiology and management of mosaic disease in ginger (Zingiber officinale Roscoe)(Department of Plant Pathology, College of Agriculture, Vellayani, 2018) Ananthu, N; KAU; Umamaheswaran, KThe study entitled ‘Etiology and management of mosaic disease in ginger (Zingiber officinale Roscoe)’ was conducted at the Department of Plant Pathology, College of Agriculture, Vellayani during 2015-2018 with the objectives to identify, characterize and sequence the genes of Ginger mosaic virus infecting ginger along with the management of the disease. As part of the study, the symptoms produced by the virus in ginger plants collected from the field and grown in glass house were observed. The symptoms on the leaves appeared as small light green flecks. These flecks eventually increased in size and formed streaks. The streaks were arranged parallel to the veins. The appearance of too many streaks on the leaves led to severe chlorosis and the leaves showed necrotic symptoms in the advanced stage. Transmission of the virus was tested in rhizome (seed material collected from infected plants) and mechanical inoculation was done using infected leaf sap to the healthy plants. The infected rhizomes resulted in 100% transmission and mechanical transmission failed to transmit the virus. Changes in total carbohydrates, chlorophyll, phenol, total soluble proteins and defense related enzymes namely peroxidase, polyphenol oxidase and phenylalanine ammonialyase were carried out at 30, 60, 90 and 120 days after infection. The study revealed an increase in the content of phenols and defense related enzymes in infected plants. An increase in carbohydrates, chlorophyll and protein in healthy plants was also observed. Protein profile study using sodium dodecyl sulphate- polyacrylamide gel electrophoresis (SDS- PAGE) indicated the presence of a novel protein with molecular weight of 20 kDa in the infected plant sample. The immunological detection techniques direct antigen coating- enzyme linked immunosorbant assay (DAC- ELISA) and dot immunobinding assay (DIBA) were carried out. Since the etiology of the virus was unknown, seven suspected viruses were tested in DAC- ELISA and antibodies specific to two viruses namely Banana bract mosaic virus (BBrMV), Cucumber mosaic virus (CMV) gave an absorbance value of 0.15 and 0.19 respectively which was three times more than the absorbance shown by the healthy leaf (0.05 and 0.07). The infected leaf tested for the presence of African cassava mosaic virus (ACMV) by triple antibody sandwich ELISA (TAS-ELISA) gave an absorbance of 0.0425 while the healthy gave an absorbance of 0.017. DIBA analysis gave positive reaction to BBrMV. Polymerase chain reaction ( PCR) was carried out with both total DNA and RNA isolated from infected ginger leaf sample. The PCR experiment was positive to Begomoviruses and negative to PVY (Potato virus Y) and BBrMV isolates. An amplicon of size 550 bp was obtained for the sample DNA using begomo degenerate primer. The sequence was subjected to BLAST analysis which indicated 74 per cent similarity to Tomato leaf curl virus Bangalore isolate. The management studies were conducted with antiviral principles like botanicals, chemicals and that of microbial origin against the virus. The experiment was conducted in completely randomized design (CRD) with 13 treatments and three replications. Karthika was the variety used for the study. Perfekt (a botanical extract-76%) at 0.5 ml L-1 and 1ml L-1, chemicals namely aspirin, salicylic acid, barium chloride, at 100 and 150 ppm concentrations and botanicals namely ten per cent leaf extracts of Mirabilis jalapa and Bougainvillea spectabilis, two per cent neem oil garlic emulsion and two per cent PGPR mix II were used in the experiment. The treatments were given at fortnightly interval. Before each spray the efficacy of the treatments were evaluated using Vulnerability Index (V.I) developed by Bos (1982). The treatments with Perfekt at the rate of 0.5 ml L-1 and 1.0 ml L-1 and ten per cent leaf extract of Mirabilis jalapa were found effective for the management of the disease. The study indicates that the mosaic disease in ginger is transmitted through rhizomes, the virus has been molecularly characterized and shows only 74% identity with Tomato leaf curl virus (TLCV) and management of the disease can be done by application of Perfekt at 0.5 ml L-1 or 10% leaf extract of Mirabilis jalapa at fortnightly interval.ThesisItem Open Access Identification of graft transmissible resistant factors and development of si RNA mediated resistance in cassava against cassava mosaic geminivirus(Department of Plant Pathology, College of Agriculture, Vellayani, 2017) Asha, B Nair; KAU; Umamaheswaran, KThe present study entitled ‘Identification of graft transmissible resistant factors and development of siRNA mediated resistance in Cassava against Cassava mosaic virus’ was carried out during the period 2012-2017 at the Department of Plant Pathology, College of Agriculture, Vellayani. The study was carried out with the objective of identification of transferability of resistance factor from resistant cassava, Sree Padmanabha to susceptible, Vellayani Hraswa by grafting and to develop siRNA mediated technology for the development of cassava plant resistant to Cassava mosaic geminivirus. Grafting experiments were conducted using resistant Sree Padmanabha as root stock and susceptible Vellayani Hraswa as scion. Symptoms like leaf mosaic, chlorotic spots, reduction in leaflet size and stunting of plants were noticed in susceptible variety. Virus concentration was found to be less in grafted plants. Grafting experiments showed the expression of an extra protein by SDS-PAGE and Coomassie staining in grafted plants which is around 38 kDa. Molecular weight of the new protein revealed the presence of extracellular protein in grafted samples. The extra proteins found in the grafted plants are assumed to be transferred from Sree Padmanabha to Vellayani Hraswa by the process of grafting. The study also involved the development of an intron hairpin RNA vector against replicase gene of SriLankan cassava mosaic virus and introduction of this construct into embryogenic cells via Agrobacterium mediated transformation. A protocol for somatic embryogenesis in cassava variety, Vellayani Hraswa was developed by using immature leaf lobes as explants. The young leaf lobes from tissue culture plantlets produced through meristem culture was used for embryogenic callus formation. Cremish white calli was initiated in Murashige and Skooge (MS) medium supplemented with picloram 12 mg L-1 in dark. For embryogenesis, the calli were transferred to MS medium supplemented with BA 2µM and NAA 1µM which resulted in the production of glassy elongated somatic embryos. The germinated cotyledonary embryos were then regenerated into plantlets by culturing in MS medium supplemented with BA 1mg L-1. Effort was taken to construct an intron hairpin RNA vector and the gene targeted for silencing was the replicase gene of SriLankan cassava mosaic virus (SLCMV). Total DNA was extracted from virus infected plants and the whole replicase gene was isolated using gene specific primers. Sequencing of the whole gene was done. BLAST analysis showed 98% similarity to replicase gene of various isolates of SLCMV. The sequence was then subjected to miRNA target prediction and restriction mapping to select suitable region for the construct. Based on this information, a fragment of 397 bp towards the 5’ end was amplified by designing a set of primers with anchored restriction sites. The primers anchored with Xho and Kpn 1sites were used for the amplification of sense strand and the primers anchored with Xba and Cla 1sites were used for amplification of antisense strand. Selected region was amplified to form sense and anti-sense fragments and cloned to pTZ57R/T cloning vector. Inserts were then released from pTZ57R/T using the corresponding restriction enzymes. The sense and anti-sense fragments were then integrated in the primary vector pHANNIBAL on either side of the pdk intron which facilitated the formation of intron hairpin RNA construct. The intron hairpin RNA construct in pHANNIBAL contained CaMV35S promoter, sense strand, pdk intron, antisense strand and OCS terminator in the order with Not 1 restriction sites. After confirmation of integration by restriction digestion, the Not1 fragment with sense and anti-sense strand were released from pHANNIBAL and ligated to the digested Not1 site in the lacZ gene of binary vector pART27 containing antibiotic resistant marker nptII and spec. the binary vector was confirmed for the presence of insert by transferring to DH5α cells and colony selection by blue white screening. Plasmid DNA isolated from transformed colonies grown on Luria agar medium supplemented with 100 mg L -1 spectinomycin were confirmed for the presence of insert. After confirmation of insert in the binary vector, it was transformed to Agrobacterium tumefaciens strain LBA4404 via freeze thaw method. Transformed colonies were selected on kanamycin selection medium at 100 mg L -1 and confirmed for the presence of binary vector and ihpRNA insert using nptII primers and primer for sense and antisense strands by PCR reaction. Cotyledons excised from the somatic embryos were transformed with LBA4404 having pART 27 by co-cultivation and the transformed embryos were selected with antibiotic pressure (Kanamycin 100 mg L-1). DNA was isolated from the transformed somatic embryos and confirmed for the presence of insert using forward primer of sense fragment and reverse primer of antisense fragments. Transformed embryos were subjected to regeneration.ThesisItem Open Access Molecular characterization of virus causing infectious chlorosis disease of banana(Department of Plant Pathology, College of Horticulture Vellanikkara, 2017) Ahamed Mujtaba, V; KAU; Anita Cherian, KThe experiment entitled “Nutrient management in strawberry (Fragaria x ananassa Duch.)” was undertaken at Regional Agricultural Research Station, Ambalavayal, Wayanad during the year 2016-17. Performance of strawberry variety Winter Dawn was evaluated under nine treatments and a control in the open field viz., FYM 10 t ha-1 + NPK 50:20:50 kg ha-1 (T1); FYM 10 t ha-1 + NPK 75:30:75 kg ha-1 (T2 ); FYM 10 t ha-1 + NPK 100:40:100 kg ha-1 (T3); FYM 20 t ha-1 + NPK 50:30:100 kg ha-1 (T4); FYM 20 t ha-1 + NPK 75:40:50 kg ha-1 (T5); FYM 20 t ha-1 + NPK 100:20:75 kg ha-1 (T6); FYM 30 t ha-1 + NPK 50:40:75 kg ha-1 (T7); FYM 30 t ha-1 + NPK 75:20:100 kg ha-1 (T8); FYM 30 t ha-1 + NPK 100:30:50 kg ha-1 (T9) and an absolute control (T10), without any nutrient application. All the treatments were on par and superior over the control (T10) in case of plant height. In case of plant spread, T2, T3, T5, T6, T7, T8 and T9 were on par and superior over the control while T1 and T4 were on par with each other but differs with other treatments. All the treatments except T2 were on par and superior over the control with respect to number of leaves per plant. Application of treatments had no significant effect on days to first flowering. In case of number of flowers and clusters per plant, T1, T2, T3, T5, T6, T7, T8 and T9 were on par and superior over the control while T4 was on par with the control (T10). Days to first harvest was minimum in T6, T7, T8 and T9 which were on par while all other treatments were on par with the control (T10).In case of number of fruits and yield per plant, T7 (FYM 30 t ha-1 + NPK 50:40:75 kg ha-1) and T8 (FYM 30 t ha-1 + NPK 75:20:100 kg ha-1) were on par and superior over other treatments including T1, T2, T3, T4, T5, T6 and T9 which were on par and superior over the control. Average fruit weight recorded under T3, T5, T6, T7, T8 and T9 were on par which was followed by T2 on par with T4 and T1. Days to final harvest was not found to be influenced by the application of different treatments. Biochemical characters of fruits viz., TSS, acidity and TSS/acidity ratio were not having any significant effect due to the application of treatments. In case of total sugars, T3, T7, T8 and T9 were having the highest content and were on par which was followed by T5 on par with T1, T2, T4, T6 and T10. The overall sensory score was highest in T7 followed by T8. Application of different treatments had no significant effect on the shelf life of strawberry fruits. N, P, K and Ca content in the plant were not significantly affected by any treatment while Mg content was found to be on par in all treatments and superior over the control. Soil analysis after the harvest of the crop revealed that the values for soil EC, available P, K, Mg and S were found to be elevated while soil pH, organic carbon and available Ca content were found to be at lower levels than the initial values before planting. It was concluded that among different nutrient combinations evaluated, T7 (FYM 30 t ha-1 + NPK 50:40:75 kg ha-1) with a BC ratio of 3.06 can be recommended for further optimization and refinement.ThesisItem Open Access Characterization, host range and management of papaya ringspot virus (PRSV)(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2018) Atheena Harish; KAU; Anita Cherian, KPapaya is an important fruit crop which is cultivated extensively both in tropics and subtropics. During the last decade, the area under papaya cultivation has dramatically increased due to the introduction of superior varieties. A major setback subsequent to the introduction of such new varieties has been the incidence of papaya ringspot disease caused by Papaya ringspot virus (PRSV) which leads to almost 100 per cent yield loss. Considering the importance of the disease, the project was undertaken with the objectives of characterization of the virus, molecular and immunodiagnosis along with disease management. The research project was initiated with purposive sampling surveys conducted in different papaya orchards of Thrissur district in order to document the symptoms under natural conditions, to assess the incidence and severity of the disease and to collect infected samples for further studies. The maximum disease incidence and disease severity recorded were 99.6 and 96.67 per cent on papaya variety Red Lady from Vellikulangara and Puthur respectively. The development of symptoms was studied under artificial conditions also through mechanical inoculation of healthy papaya seedlings with virus inoculum maintained in insect proof net house conditions. The salient diagnostic symptoms of the disease observed on leaves were chlorotic spots, mottling, vein thickening, puckering, leaf distortion, shoestring symptom along with presence of oily streaks on the petiole. The fruits of infected plants presented typical oily concentric or broken ringspots on fruit surface along with malformation. Histopathological studies of infected leaves revealed disruption of the epidermis, disorganization of parenchyma, disintegration of chloroplasts and deposition of crystalline bodies. The studies on virus transmission confirmed that it is transmitted through plant sap from infected to healthy papaya plants. Seed transmission studies revealed that PRSV is not seed -borne. Twenty one plant species including weeds seen in and around papaya orchards were tested for studying the host range of the virus and only five plant species viz., Cucumis sativus, Cucurbita moschata, Trichosanthes cucumerina, Momordica charantia and Chenopodium amaranticolor developed symptoms after artificial inoculation of PRSV and thus proved to be the hosts of the virus. Morphological characterization done using electron microscopy showed the presence of typical flexuous rod particles of size 807.74 nm x 12 nm which indicated that the virus belongs to genus Potyvirus and the etiology of the disease was confirmed as Papaya ringspot virus. Immunodiagnostic technique was validated using Direct Antigen Coating - Enzyme Linked Immuno Sorbent Assay (DAC-ELISA) and infected samples showed positive reaction to PRSV antiserum and could be detected at 1:200 dilution of primary antibody and 1:10,000 dilution of secondary antibody. Molecular characterization of PRSV was also carried out through Reverse Transcription Polymerase Chain Reaction (RT-PCR). The nuclear inclusion b (NIb) gene and the coat protein (CP) gene were amplified using reported primer pairs which yielded amplicons of approximate size of 1700 bp. The PCR products were outsourced for sequencing and in silico analysis of the sequences obtained revealed that the isolates of present study are more similar to Calicut isolate of PRSV, PRSV- Ca (DQ666640.1) A pot culture experiment under insect proof conditions was also conducted to evaluate the effects of selected botanicals, chemicals and biocontrol agents for disease management. Among the fourteen treatments, Bougainvillea leaf extract, 10 per cent (T7) was the most effective with lowest disease severity (6.67%) followed by foliar spray and soil drenching with Pseudomonas fluorescens 2 per cent (T3) with a disease severity of 11.11 per cent as against 97.77 per cent recorded in untreated control plants. Plant height recorded after each treatment application revealed that both 10 per cent Bougainvillea leaf extract (T7) and 2 per cent P. fluorescens are equally superior to all other treatments. However, with respect to mean girth of stem, maximum value (2.91 cm) was recorded in P. fluorescens (T3) The data on virus titre of all treated plants assessed through DAC-ELISA revealed that the concentration of virus particles was minimum in plants treated with T7 and T3. The outcome of this study would facilitate early detection and elimination of source of virus infection and thereby prevent the spread of disease in the field. The information generated on molecular characterization of PRSV isolates under could be applied in genetic engineering. The project also revealed the potential of botanical, Bougainvillea spectabilis leaf extract and biocontrol agent, Pseudomonas fluorescens for the ecofriendly management of papaya ringspot disease.ThesisItem Open Access Triazole,strobilurin and its combination fungicides for the management of anthracnose and fruit rot of chilli(Department of Plant Pathology, College of Agriculture, Vellayani, 2018) Anjana, R S; KAU; Joy, MA study entitled ‘Triazole, strobilurin and its combination fungicides for the management of anthracnose and fruit rot of chilli’ was conducted during 2016 - 18 at Department of Plant Pathology, College of Agriculture, Vellayani with the objectives to study the host range of the pathogen Colletotrichum capsici and to develop management strategy to control the disease using new generation fungicides. A survey was conducted at Vellayani, Kumarakom, Thrissur, Pattambi, Ambalavayal and Padanakkad during 2016 – 17 to screen the most virulent isolate of C. capsici in chilli (Capsicum annuum). During the survey period, C. capsici was found causing the disease in five and C. gloeosporioides in one locations. The maximum disease incidence (70 %) and severity (45 %) by C. capsici was recorded from Padanakkad. Except from Ambalavayal, five pure cultures of C. capsici (C1 to C5) were obtained and Koch’s postulate is proved. C. capsici produced white to dirty white, sparse mycelial growth on PDA, which later turned into dirty grey colour. Days taken to cover petridish (9 cm radius) ranged from 7.4 to 8.3 days. Mycelium was hyaline, septate and branched. Black colored acervuli were produced after 20 - 30 days of incubation and its diameter ranged from 21.85 - 45.82 μm, with 18 - 47 dark setae of 72.50 - 110.41 μm length. Conidiophores are hyaline, short and cylindrical with sickle shaped single celled conidia having an oil globule at the centre. The average size of the conidia was 20.04 - 23.48 μm x 2.58 - 3.22 μm. Based on screening of isolates through leaf and fruits inoculation of chilli variety ‘Vellayani Athulya’, C3 was identified as the most virulent isolate. The identity of C. capsici (C3) was confirmed by PCR using ITS primers, sequencing of amplicon, BLAST and phylogenetic analysis. The best solid and liquid media for growth and sporulation of C. capsici was potato dextrose medium, the optimum temperature was 30oC and pH was 6.5. The growth of C. capsici was studied under different light conditions and the fungus growth was maximum in 8 hour light and 16 hour dark under white light at 20 lux intensity. Host range of C. capsici was studied in different vegetable crops viz. Capsicum chinense, C. frutescens, cowpea, brinjal, tomato and bhindi. C. capsici infected all the host plants tested and brinjal was found as the ideal host plant. Among eight KAU varieties of chilli viz. Vellayani Athulya, Jwalamukhi, Jwalasakhi, Ujwala, Anugraha, Keerthi, Vellayani Thejus and Vellayani Samrudhi, screened against C. capsici with leaf and fruits inoculation, Vellayani Athulya was found to be the most susceptible variety to the disease, whereas Vellayani Thejus and Vellayani Samrudhi were found comparatively resistant to leaf and fruit infection. Under in vitro evaluation of new generation fungicides by poisoned food technique, azoxystrobin 11 % + tebuconazole 18.3 % SC at 10 ppm, pyraclostrobin 20 % WG at 50 ppm and hexaconazole 5 % EC + pyraclostrobin 20 % WG at 100 ppm completely inhibited the mycelial growth and proved to be most effective. All fungicides significantly inhibited spore germination of C. capsici. Hexaconazole 250 ppm completely inhibited germination. Pyraclostrobin 20% WG at 10 ppm, hexaconazole 5 % EC + pyraclostrobin 20 % WG at 50 ppm, tebuconazole 25.9 % EC and hexaconazole 5 % EC at 100 ppm were also equally effective in inhibiting germination of spores and were statistically on par. A pot culture study was conducted with chilli variety ‘Vellayani Athulya’ to evaluate the efficacy of selected new generation fungicides. The selected treatments were imposed only once, after 18 days of flowering when at least 25 per cent of fruits were at maturity stage. At recommended dose, the maximum disease suppression was recorded with 0.24 % of copper oxy chloride 50 % WG (90.59 %), followed by 0.1 % of hexaconazole 5 % EC + pyraclostrobin 20 % WG (73.50 %), 0.15 % of azoxystrobin 11 % + tebuconazole 18.3 % SC (70.94 %) and 0.1 % of tebuconazole 25.9 % EC (68.70 %). At higher (double the recommended) doses of respective fungicides, disease suppression was more. Biocontrol agents were also effective, but the disease suppression was less with 22.22 per cent for Trichoderma viride and 43.58 per cent for Pseudomonas fluorescens compared to the new generation fungicides. Hence anthracnose and fruit rot of chilli can be effectively managed by foliar spray of hexaconazole + pyraclostrobin combination fungicide and it may be subjected to mutlilocation and multiseasonal trials before recommendation.ThesisItem Open Access Characterization and management of yellow mosaic disease of black gram (vigna mungo (L.) hepper)(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2018) Divya Jayakumar, V J; KAU; Sumiya, K VBlack gram (Vigna mungo (L.) Hepper) is one of the important pulse crop in India and an excellent source of good quality protein. Yellow mosaic disease (YMD), caused by a whitefly transmitted geminivirus is the major constraint for black gram cultivation. Yellow mosaic disease of pulses is extensively studied from different parts of the country. But no study has been conducted in Kerala. Hence, the present study was undertaken to characterize the virus causing yellow mosaic disease in black gram in Kerala and to evolve suitable strategies for its management. Purposive sampling surveys were conducted in black gram growing areas of Palakkad and Malappuram districts, covering 13 fields at nine locations to study the incidence and symptomatology of yellow mosaic disease. The disease incidence in the fields varied from 12 to 100 per cent. Common symptoms observed in the field were typical yellow mosaic, puckering and cupping of leaves, distortion of leaf lamina and drastic reduction in size of younger leaves. Irregular whitish discolouration of leaves which turned papery white on maturity was also observed in some fields. Complete yellowing of leaves along with brown discoloration between the veins and vein banding symptoms which were not reported by earlier workers were also observed in the field. Electron microscopic studies revealed the presence of geminate particles of 15-18 x 30 nm size in infected black gram samples suggesting the association of a geminivirus with the disease. Whitefly transmission of the virus to healthy black gram plants was attempted and 80 per cent transmission was achieved. PCR amplification using virus specific primers revealed the presence of Mungbean yellow mosaic virus (MYMV) and Horsegram yellow mosaic virus (HYMV) in the samples. MYMV was detected in infected samples from nine fields out of the 13 fields surveyed. HYMV was detected in six fields, which include five fields in which MYMV was also detected revealing the occurrence of mixed infection in the field. Five representative isolates were sequenced at Agrigenome Labs, Kakkanad, Ernakulam. In silico analysis of these sequences revealed that the coat protein region of the isolates showed more than 90 per cent homology with MYMV isolates. This confirmed the presence of MYMV as the major virus in yellow mosaic disease of black gram in Kerala. Phylogenetic analysis revealed that the isolates from the present study are more closely related to MYMV isolates from southern parts of India and distantly related to Mungbean yellow mosaic India virus (MYMIV) isolates, which were reported from northern parts of India. Host range studies conducted in insect proof cages under glass house condition showed that the virus could be transmitted through whiteflies only to horse gram. Symptoms were observed in horse gram and Synedrella nodiflora, a predominant weed found in the field 20 -25 days after inoculation. But the presence of virus was confirmed by PCR only in symptomatic horse gram and not in Synedrella nodiflora. A field experiment was conducted during Rabi 2017-18 at RARS, Pattambi and evaluation of effectiveness of botanicals, biocontrol agents and other organic products revealed that application of Pseudomonas fluorescens as seed treatment @ 10g/kg seed and foliar sprays @ 10g/l at fortnightly intervals starting from 15 days after sowing or foliar sprays of 10 per cent aqueous extract of leaves of Bougainvillea spectabilis or roots of Boerhaavia diffusa at fortnightly intervals starting from 15 days after sowing are effective in reducing the yellow mosaic disease. The present study reveals that MYMV is the virus associated with the YMD of black gram in Kerala and it can be effectively managed by prophylactic application of Pseudomonas fluorescens, 10 per cent leaf extract of Bougainvillea spectabilis or 10% root extract of Boerhaavia diffusa. This is the first report on identification of MYMV associated with yellow mosaic disease of black gram in Kerala.ThesisItem Open Access Characterization and management of powdery mildew of yard long bean (vigna unguiculata subsp.sesquipedalis (L.) verdc.) under protected cultivation(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2018) Rahila Beevi, M H; KAU; Sainamole Kurian, PYard long bean (Vigna unguiculata subsp. sesquipedalis (L.) Verdc.) is believed to be selected and developed from cowpea (Vigna unguiculata (L.) Walp.) for its long, succulent pods which are used as a vegetable. In Kerala, it is one of the most preferred vegetables having very high amount of protein, iron, calcium, vitamin A, Vitamin C and dietary fibre. It is considered as a remunerative crop under protected condition owing to its high market demand. However, incidence of diseases is a major setback hampering the production of yard long bean under protected conditions among which, powdery mildew is the most devastating one. In this background, the present study was undertaken to characterize the pathogen causing powdery mildew of yard long bean and to formulate a management strategy for the disease under protected cultivation. Purposive sampling surveys were conducted in seven locations of Thrissur district and the disease severity varied from 1.67 to 67.33 per cent. The results of the survey indicated that the severity of disease was more during pod bearing and harvesting stage. Since powdery mildews are obligate parasites, characterization was done based on the microscopic observation of pathogen present on the leaves. The fungi produced hyaline, branched and septate hyphae. The conidiophores were erect and cylindrical on which conidia were born in chains. Variability was observed regarding conidia and conidiophore characters of powdery mildew collected from different locations, based on which the isolates were grouped into two viz., PM 1 and PM 2. PM1 type was observed in all locations except Vellanikkara. Based on the morphological characteristics of conidia and conidiophores, it was identified as Erysiphe polygoni. PM 2 type obtained only from Vellanikkara in which conidia and conidiophore characters were similar to Podosphera sp. which is very rarely reported on legumes. Hence, its identity was further confirmed as Podosphaera xanthii by molecular characterization. The rRNA-ITS sequence was deposited in NCBI Genbank database with accession number MH645799. This is the first report of powdery mildew of yard log bean incited by Podosphaera xanthii. In-vitro evaluation of 17 treatments including fungicides, biocontrol agents and botanicals by spore germination technique revealed that all the treatments caused cent per cent inhibition of conidial germination. For taking forward eight promising treatments to the field experiments, they were tested in-vitro on detached leaves by artificial inoculation of conidia from infected leaves. Based on the per cent leaf area infected, two systemic fungicides, one contact fungicide, two biocontrol agents and one botanical were selected for field evaluation. Field experiments were conducted simultaneously inside polyhouse and rain shelter to evaluate the performance of selected fungicides, biocontrol agents and botanicals against powdery mildew. Among the treatments, low disease severity of 4.33 per cent and 7.67 per cent was recorded in T1- difenoconazole and T2 – tebuconazole respectively in polyhouse and these treatments were statistically on par. In rain shelter also, T1- difenoconazole and T2- tebuconazole recorded low disease severity of 7.67 per cent and 10.67 per cent respectively. The performance of wettable sulphur at lower and higher concentration did not differed significantly. All the four non-chemical treatments were equally effective in managing the disease both in polyhouse and rain shelter. Correlation analysis between the meteorological parameters and disease severity revealed that per cent disease severity was negatively correlated with temperature and relative humidity both in polyhouse and rain shelter. Analysis of population of phylloplane microflora showed that, there was a drastic reduction in the population of phylloplane fungi and bacteria after spraying chemical fungicides which is an indication of the toxicity and non-selectivity of these chemicals. Survival ability of biocontrol agents sprayed on the leaves were studied and found out that both Trichodema viride and Pseudomonas fluorescens survived on the leaves for seven days. Residue analysis of difenoconazole, the most effective chemical fungicide revealed that the compound with initial deposition of 0.21 mg kg-1 dissipated to 0.09 mg kg-1 after seven days in polyhouse whereas, the residue after seven days in rain shelter was 0.19 mg kg-1. The faster degradation of the chemical inside polyhouse may be attributed to the higher temperature prevailed during the experiment. Evaluating the results various experiments in the present investigation, it was found that, even though chemical fungicides provided best disease control, considering their toxic effect on beneficial non target microflora on the phylloplane and the residue left on edible pods, biocontrl agents such as Trichoderma viride and Pseudomonas fluorescens which exhibited consistent performance with moderate disease control and sufficient survival on the leaf surface would be ideal to control powdery mildew of yard long bean if applied at right time. Moreover, frequent application of systemic fungicides with single site action can result in the development of resistant strains of pathogens. So such chemicals should be adopted only if the disease severity is very high and cannot be managed with biocontrol agents.
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