1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)

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    Characterisation of novel strains of soil-inhabiting Trichodermaspp. and their utilization in soil-borne disease management
    (Department of Plant Pathology, College of Agriculture ,Vellayani, 2022-05-04) Athira Nair; Sible George Varghese
    The research work entitled “Characterization of novel strains of soil-inhabiting Trichoderma spp. and their utilization in soil-borne disease management” was conducted during the period 2019-2021 at the Department of Plant Pathology, College of Agriculture, Vellayani, Thiruvananthapuram, Kerala. The study aimed at characterization of novel strains of Trichoderma spp. obtained from virgin forest soils of Kerala; and their evaluation against major soil-borne diseases of tomato and vegetable cowpea. Two reference strains viz., T. harzianum (NBAIR strain) and T. asperellum (KAU strain) along with 11 different isolates of Trichoderma spp. from the previous study were used to carry out the present study. All the isolates showed white coloured mycelial growth except for isolate TRML-1 which showed creamish white coloured mycelium. The textures of the colonies were sparse, spreading and cottony or fluffy growth at centre. Moreover, the sporulation and growth pattern also varied among the isolates which showed spores with varying shades of green. The spore characters including the size and shape of the spores of all the isolates were observed under the microscope at 100x magnification. Spores of isolate TRML-1 (4.448 µm x 4.172 µm) were the largest while the spores of isolate TRSN-1 (2.197 µm x 2.881 µm) were the smallest. The shape of the spores varied from globose, sub-globose, ovoidal or ellipsoidal. Pathogenicity tests to prove Koch’s postulate revealed that symptoms of Fusarium wilt (yellowing, drying of foliage followed by wilting of the plant) occurred at five days of inoculation of the pathogen. Pre-emergence damping off symptoms were seen as water soaked lesions leading to rotting of the radicle thus preventing the germination of the seeds while post-emergence damping off exhibited softening of the tissues of collar region leading to toppling of the seedlings at about 13 days of pathogen inoculation. In the pathogenicity test, 77.78 per cent disease incidence was observed in Fusarium wilt of vegetable cowpea while 70.73 per cent and 100 per cent incidence was observed for pre- and post-emergence damping off of tomato. The radial growths of all the Trichoderma isolates as well as of both the pathogens were recorded. The isolates TRMW-2, TRPN-3, TRPN-11, TRPN-14 and TRPN-15 were fast growing, covering the Petri plate at three days after inoculation (DAI). Among the pathogens, it was observed that P. aphanidermatum completed its growth at 3 DAI while F. oxysporum was slow growing fungus that completed its growth at 9 DAI. In vitro screening of Trichoderma isolates against both pathogens was carried out. Antagonistic characters viz., antibiosis, lysis and overgrowth along with per cent inhibition and antagonistic index were calculated based on which five potential isolates were selected to carry out further studies. Isolates TRMW-2, TRPN-3, TRPN-11, TRPN-15 and TRPN-17 showed all the three antagonistic properties and high antagonistic index against F. oxysporum; the highest inhibition (47.78%) being shown by the isolate TRPN-3. Similarly isolates TRMW-2, TRKR2, TRPN-15 and TRPN-18 showed all the three antagonistic properties and high antagonistic index against P. aphanidermatum; the highest inhibition being exhibited by the isolates TRPN-7, TRPN-18 and TRML-1 (70%). Volatile metabolites produced by the isolates TRPN14 and TRPN-17 showed the highest inhibition on F. oxysporum (71.25%) and P. aphanidermatum (27.78%) respectively. RAPD-PCR of genomic DNA of seven isolates of Trichoderma spp. was done using four primers viz., OPA-02, OPA-03, OPA-09 and OPA-10. The dendrogram showed two major groups; the first with TRPN-3, TRPN-17, TRKR-2, T. asperellum (KAU strain) and T. harzianum (NBAIR isolate), and the second with isolates TRPN-11 and TRMW-2. Molecular identification of ten isolates of Trichoderma spp. was also done using ITS-PCR. The best matching sequences from GenBank were recorded and phylogenetic tree was constructed. The isolates were identified as T. harzianum (TRMW-2, TRPN-3, TRPN-14, TRPN-17), T. koningiopsis (TRKR-2), T. lixii (TRPN-11, TRPN-15) and T. asperellum (TRPN-18). Talc based formulations of all the isolates applied as seed treatment and as an additive in potting medium brought about successful control of pre-emergence and postemergence damping off, among which TRKR-2, TRMW-2 and TRPN-11 were more effective compared to the treatments with other isolates for both pre- and post-emergence damping off. The population of Trichoderma spp. in potting medium in different treatments of the in vivo experiment ranged from 8 x 104 to 12 x 104 cfu g-1 .
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    Molecular characterization of promising isolates of trichoderma spp. and their field evaluation against fusarium wilt of vegetable cowpea
    (Department of plant pathology, college of agriculture,Vellayani, 2023-08-07) Jeevidha, M.; Sible, George Varghese
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    Strain evaluation and production technology of shittake mushroom ( Lentinula edodes ( Berk. ) pegler)
    (Department of Plant Pathology, College of Agriculture, Vellayani, 2016) Deepa Rani, C V; Lulu Das
    The present investigation on "Strain evaluation and production technology of Shiitake mushroom (Lentinula edodes (Berk.) Pegler' was conducted at Department of Plant Pathology, College of Agriculture, Vellayani, Thiruvananthapuram during the period 2012-2015. The aim of the experiment was to exploit various strains of Lentinula spp. for novel production technology and their phylogeny analysis through physiological and molecular studies. Surveys were collected during pre and post monsoon periods of May to December from different parts of Thiruvananthapuram, Kollam, Wayanad, Idukki, Pathanamthitta, Kannur and Kasargode districts. Six isolates of sp. (VLYN- 1 to VLYN-13) obtained during the survey were identified and compared with procured reference strains of Lentinula edodes (LE-1 to LE-5 from GB Pant University of Agricultural and Technology, Pantnagar, Uttarakhand) and LE-6 strain (Maharana Pratap University of Agriculture and Technology, Udaipur) . Morphologically the native isolates of Lentinus spp. had concave, funnel and convex pileus with varying colors and were leathery in nature.L. edodes strains in contrast had convex pileus with chocolate brown and golden yellow sporocarps which were fleshy and edible. Phylogenetic analysis of all six strains of L. edodes using RAPD markers confirmed the variability between the strains. Maximum similarity coefficient of 74.10 per cent was observed between LE-2 and LE-6 strains while LE-2 and LE-4 strains showed a minimum similarity coefficient of 35.70 per cent. Further studies by ITS sequencing showed that all the L. edodes strains tested in the study showed 99- 100 per cent similarity with the known sequences off L. edodes available in NCBI database while that of native isolates showed 99- 100 per cent similarity to Lentinus tuber-regium and Lentinus connatus thus confirming the variability between Lentinus and Lentinula sp. All the six strains of L. edodes, showed maximum mycelial growth in malt extract peptone dextrose agar in solid and oat meal broth in liquid medium. L. edodes strains preferred temperature of 20 °C with an acidic pH of 6. Dark and ambient light conditions favored maximum mycelial growth and biomass production for L. edodes culture. Although a minimum period of 16.33 days was required for full mycelial run in maize grains but due to comparatively less contamination rate in paddy grains which took 18.33 days for completion of mycelial run were selected as best substrate for further studies. Different substrates were evaluated for the development of a cultivation package for shiitake mushroom. Results showed that LE-1 strain took minimum of 71.00 days for initiation of sporocarp in sawdust supplemented with 20 per cent wheat bran. Hard wood sawdust especially of teakwood was used in the study. The substrate based on paddy straw and banana pseudo stem were not found effective for pinhead initiation and thus failed to produce sporocarps. LE-1 produced maximum sporocarp (11.33) in sawdust + 20 per cent wheat bran which was followed by LE-3 (10.63) in sawdust + 20 per cent rice bran. Maximum yield of 290.66 g/ 500 g substrate was obtained in sawdust + 20 per cent wheat bran by LE-6 strain. Maximum biological efficiency of 58.13 per cent was also recorded in LE-6 in sawdust supplemented with 20 per cent wheat bran substrate. Substrates like paddy straw and sawdust amended with 20 per cent wheat bran substrates were evaluated for the development of native isolates of Lentinus tuberregium and Lentinus connatus . Results showed that maximum biological efficiency of 58.00 per cent was obtained by Lentinus tuber-regium whereas 36.60per cent biological efficiency by Lentinus connatus in sawdust amended with 20 per cent wheat bran substrate. Nutrient analysis of all the six strains showed that carbohydrate content ranged between 35.29 per cent to 40.23 per cent, protein 18.33 per cent to 21.66 per cent, crude fibre 22.33 per cent to 27.33 per cent, Vitamin- C 2.53 per cent to 3.50 per cent, ash 2.70 per cent to 4.40 per cent and lipid 2.46 per cent to 3.60 per cent. Mineral content of L. edodes included Ca (11.00 mg to 19.00 mg/ 100 g), Mg (0.46 to 1.10 mg/ 100 g), Fe (1.36 mg to 1.80 mg/ 100 g), Mn (1.53 mg to 2.63 mg), P (1.65 mg to 2.87 mg), K (16.33 mg to 25.20 mg), Na (13.00 mg to 23.66 mg) and Zn (19.66 mg to 28.33 mg/ 100 g). Sensory evaluation of mushroom products made from L. edodes was carried out by a panel of judges for various characters of which mushroom masala scored maximum for texture, taste, flavor and overall acceptability when compared to other recipes like mushroom cutlet, scramble, soup, baji and biscuit. As part of the study, paddy grain was found to be the most suitable substrate for spawn production of L. edodes and teakwood sawdust amended with 20 per cent wheat bran was the most efficient bed substrate. LE-6 strain was superior in terms of yield and biological efficiency. Therefore findings of the above investigation recommends the adoption of a suitable cultivation package for shiitake mushroom by using low cost substrates (hardwood sawdust) available in Kerala in plains and hilly regions.
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    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; Sainamole Kurian, P
    Yard 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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    Exploitation of indigenous bacterial antagonists against root-knot nematode, meloidogyne incognita (kofoid and white ) chitwood
    (Department of Nematology, College off Agriculture, Vellayani, 2018) Vishnu, J S; Nisha, M S
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    Standardisation of nursery management practices in pachotti (Symplocos cochinchinensis (Lour.) S. Moore)
    (Department of Plantation Crops and Spices, College of Agriculture, Vellayani, 2018) Ajil, M S; Deepa S Nair
    The study entitled “Standardisation of nursery management practices in pachotti (Symplocos cochinchinennsis (Lour.) S. Moore)” was carried out in the Department of Plantation Crops and spices, College of Agriculture, Vellayani durng 2017-18. The objective of the study was to evaluate the propagation efficiency of different propagules viz., seeds, stem cuttings and root cuttings and to standardise the potting media for the nursery plants of pachotti. The propagules viz., seeds, stem cuttings and root cuttings for the study were sourced form Jawaharlal Nehru tropical Botanical Gardens and Research Institute, Palode, Thiruvananthapuram and from Wayanad district. The seeds were subjected to in vivo and in vitro germination studies. In in vivo study, among the pretreatments tried, viz., physical treatments, chemical priming and bio priming, only physical treatment of scarification (with sand paper) responded with a very low germination of 2 per cent. The germination commenced after two months of the treatment. Other in vivo pretreatments as well as in vitro treatments did not give any germination. In vegetative propagation, stem cuttings were exposed dto hormone/chemicals (auxins, phloroglucinol and salicylic acid (SA) pretreatments for two hours before planting. When pretreated with SA @ 10 and 20 mg L -1, at three months after planting, the hardwood cuttings responded with 30 pere cent survival, whith a shoot length of 2.99 mcm and 3.62cm, respectively. The semihardwood cuttings pretreated with SA@ 20 mg L-1 responded with 23.33 per cent survival with a higher shoot length of 3.72 cm. Both the hardwood and semi hardwood cuttings pretreated with SA 20 mgL-1 had on par values with respect to shoot length. Root cuttings were pretreated with different concentrations of various types of auxins. Root cuttings pretreated with IAA @ 250 mg L -1, after three months of planting responded with 33.33 per cent survival with a shoot length of 5.73 cm. Though root cuttings had slightly higher survival percent and shoot length, hardwood cuttings were selected for the valuation of potting media due to better availability and ease in procurement. The three month old hardwood cuttings pretreated with SA @ mgL-1 were then transplanted to ten different potting media comprising of two basal media viz., soil:coipith compost :cowdung (1:1:1) (B1) and soil : soirpith compost : vermicompost (1:1:1) (B2), and each in combination with biofertilisers @ 5g plant -1 viz., PGPR (Plant Growth Promotng Rhizobacteria) Mix I, Azospirillum, PSB (Phosphorus Solubilising Bacteria ) and AMF (Arbuscular Mycorrhizal Fungi). At fourth month after transplanting, B2 in combination with biofertilisers were found to be significantly superior to B2, B1 and B1 in combination with biofertilisers with respect to morphological parameters. B2 +PGPR Mix I recorded highest shoot length (11.50 cm) and number of leaves (10.50) which was on par with B2+Azospirillum, B2+PSB and B2+AMF; the highest number of branches (1.92) was observed in B2+ Azospiriillum which was on par with the treatments , B2+ PGPR Mix I, B2+PSB and B2+AMF. The fresh and dry weight of shoots were the highest (21.35 g and 4.78 g respectively) in B2 +PGPR Mix I which was on par with B2+ AMF. B2+ AMF recorded highest values (4.77 cm, 0.30 mm, 3.28 g and 0.0092 g, respectively) with respect to root growth parameters viz., root length, root girth , fresh and dry weight of roots. The physiological parameters, leaf area index (1.36) and leaf area duration (34.63 days) were the highest in B2+ PGPR Mix I which was on par with B2 in combination with other biofertilisers. The phytochemical analysis indicated that carbohydrate content (80.9 mg g-1) of plant tissue was the highest in B2+PGPR Mix 1, which was on par with B2+PSB, B2+Azospirrillum and B2+AMF. Chlorophyll content was found to the highest (1.20 mg g-1) in B2+ Azospirillum which was on par with B2+PGPR Mix I. The same treatment recorded the highest soluble protein content (20.31mg g-1) and it was on par with B2 in combination other biofertilisers. The nutrient analysis of plant tissue showed that nitrogen (2.22 percent ) and potassium (2.15 per cent ) content was significantly higher in B2+ Azospirillum. B2+PSB Recorded higher phosphorus content (0.26 per cent) among the treatments. The study indicated that nursery plants in the potting media B2 in combination with biofertilizers gave better performance with respect to morphological parmeters, physiological parameters, phytochemicals and plant nutrients. Among the various potting media tried, B2+AMF recorded significantly higher plant growth potential (0.522) followed by B2 + PGPR Mix I (0.428). In the study, hardwood cuttings were identified as the preferred planting material for the nursery establishment of pachotti. The cuttings could be treated with salicylic acid @ 20 mg L-1 for initial establishment of nursery plants. The preferred potting media for transplanting the established cuttings for raising the nursery plants of pachotti is Soil : Coirpith compost : Vermicompost (1:1:1) +AMF (5g/plant).
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    Physiological and biochemical studies on growth, development and yield of ginger (Zingiber officinale rosc.)as influlenced by bioinoculants and phosphorus fertilization
    (Department of Plant Physiology, College of Agriculture, Vellayani, 2018) Amritha Lekshmi, M G; Viji, M M
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    Soil and nutrient management for supperssion of fusarium wilt disease of yard long bean (vigna unguiculata subsp. sesquipedalis (L.) verdcourt)
    (Department of Soil Science & Agricultural Chemistry, College of Agriculture, Vellayani, 2018) Sooraj, R S; Biju Joseph
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    Economic assessment of the use of microbial inoculants in black pepper (Piper nigrum L.) in Idukki district
    (Department of Agricultural Economics, Vellayani, 2017) Salma Muslim; Santha, A M
    The research entitled ‘Economic assessment of the use of microbial inoculants in black pepper (Piper nigrum L.) in Idukki district. The objectives of the study were to quantify the extent of use of microbial inoculants (MI) used in black pepper, assess the economics of microbial inoculants (MI) application and identify the constraints of microbial inoculants adoption in pepper cultivation. At the first stage two blocks namely Kattappana and Nedumkandam were selected purposively and Irattayar and Nedumkandam panchayat were selected respectively from the 2 development blocks. The required information was collected from 30 MI using farmers and 30 non-MI farmers of black pepper by simple random sampling from the two panchayats. Thus the total sample size was 60. Percentage analysis was done to analyze socio economic variables and extent of adoption of MI. Cost ABC concept was used to calculate the cost of cultivation of MI using farmers and non-MI farmers separately. Resource use efficiency was calculated using Cobb Douglas production function and constraints were ranked by Garret’s ranking technique. Black pepper occupied about 45 per cent of cropped area and 30 per cent area occupied by cardamom. Plantation crops like cocoa, coffee, spices like nutmeg clove, vanilla and annuals like banana and vegetables were also cultivated in this area. Major varieties of black pepper cultivated were Panniyur I, Panniyur 4, local varieties like Karimunda, Neelamundi, Vellamundi, Kottanadan, Kuthiravaly, Kalluvallyand major standards for trailing pepper were Murukku, Silver Oak and Kilinjil. Average size of land holding was 1.85 ha for MI using farmers and 2.10 ha for non-MI farmers. Seventy three per cent of MI using farmers and 56 per cent of non-MI farmers had holdings ranging from 0.4-1.2 ha under pepper. Forty percent of high income farmers were following non-MI pepper farming. Analysis of extent of use of microbial inoculants revealed that only 33 per cent were following the recommended rate of MI whereas 46.6 per cent of farmers used in excess.Total cost of cultivation of black pepper per hectare was more for non-MI farmers when compared to MI using farmers. Cost A1 of MI adopted farmers was Rs. 133797.24 ha-1 and that for non-MI was Rs. 155720.64 ha-1. Cost C was calculated as Rs. 295050.13 ha-1 and Rs. 439399.87 ha-1 for MI using famers and non-MI respectively. Major share of cost A1 was contributed by cost of hired labourfor both categories followed by cost of manures, fertilizers and soil ameliorants. Yield of black pepper did not show much difference, but the farmers using MI were mostly following organic farming, fetches a higher price of Rs.700 per kg against the price ofRs.680 per kg for the non-MI famers. Net returns at cost C for MI using farmers was Rs. 135749.75 which was higher than that of non-MI farmers. BC ratios were 1.8 and 1.23 for MI adopters and non-MI farmers respectively at cost C. The Cobb Douglas production function analysis showed that number of bearing pepper vines had a positive and significant impact on yield in both the cases. In case of MI using farmers along with number of bearing vines, quantity of manures had positive and significant impact on yield. Quantity of MI showed positive coefficient but was non-significant. For the non-MI pepper farmers, number of hired labour and quantity of manures showed positive and significant impact in addition to number of bearing pepper vines. Difficulty in proper identification of pests and diseases in the study area, less availability of microbial inoculants other than Pseudomonas and Trichoderma, Lack of knowledge about recommended method, dose and time of application of MI and climate change were the major constraints observed. Present research revealed that by using MI, farmers could reduce the use of chemical fertilisers and pesticides; thereby they could reduce the cost of cultivation and increase profitability. Excess adoption of MI was prominent among the users and proper guidance is required to the farmers on the application of recommended dose of microbial inoculants along with adequate availability of all microbial inoculants.
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    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; Surendra Gopal, K