Browsing by Author "Joy, M"

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Evaluation of beneficial fungal root endophyte, Piriformospora indica for the management of Tomato leaf curl virus
(Department Of Plant Pathology College Of Agriculture, Vellayani, 2021-12-30) Saru Sara Sam; Joy, M
The research work entitled “Evaluation of beneficial fungal root endophyte, Piriformospora indica for the management of Tomato leaf curl virus” was done at the Department of Plant Pathology, College of Agriculture, Vellayani, Thiruvananthapuram during the academic year 2019-2021 with the objectives of evaluation of the beneficial fungal root endophyte Piriformospora indica for the management of Tomato leaf curl virus (ToLCV) in tomato; and elucidating the role of reactive oxygen species (ROS) and antioxidant enzymes in the tripartite interaction. ToLCV symptoms were assessed and maintained in insect proof nets from the various field at College of Agriculture, Vellayani, Thiruvananthapuram. The major symptoms observed includes mild curling with yellow speckles, severe leaf curling with blisters on leaf, stunted growth and reduced leaf size with flower abortion. Tomato variety Vellayani Vijay showed a disease incidence of 72.3 to 100 per cent with vulnerability index of 68.5 to 71.0 at different fields, while Anagha variety recorded an incidence of 67.0 per cent and vulnerability index of 54. The presence of ToLCV was confirmed using the universal primers viz., Deng and AV/AC that amplifies the coat protein of Begomovirus which produce amplicons of 520 bp and 575 bp respectively under specified conditions. P. indica-colonization in tomato variety Vellayani Vijay was done in portray mixture amended with 2 per cent gram flour. P. indica spores were observed from 3 day after colonization (DAC) and the spore size increased by subsequent days. P.indica-colonization enhanced the growth parameters including plant height, shoot height, and root and shoot biomass. The tomato plants colonized with P. indica showed an increase in shoot height, number of branches, number of leaves, number of flower, fresh shoot weight, dried shoot weight, fresh root weight and dried shoot weight by 34, 117, 96, 86, 45, 66, 45 and 120 per cent respectively compared to the control at 60 DAC. The days taken for flowering in P. indica-colonized plants were decreased by 12 days and the yield per plant in P. indica-colonized was 892.46 g against 449.51g. P.indica-colonization decreased incidence and severity of fungal and bacterial diseases under field conditions. Moreover, it recorded a drastic reduction in the severity of ToLCD by 58 percent. Tomato plants were subjected to pre- and postcolonization of P. indica challenged with ToLCV through wedge grafting at 2, 5, 10 and 15 days interval. Pre-colonized tomato plants decreased the severity of ToLCD by 66 per cent, while post-colonization decreased the severity by 26 per cent at various intervals of treatments. Further, P. indica-colonization promoted flowering and fruit set against complete flower abortion in non-colonized plants challenged with ToLCV under pot studies. The best treatments selected from pre- and post- inoculation of the fungus include P. indica-colonization followed by graft transmission of the virus after 15 days, and graft transmission of the virus followed by P. indica-colonization after 2 days respectively. Amplification of the virus by polymerase chain reaction (PCR) using Deng and AV/AC primers also revealed that the virus titer was the least in P. indica-pre-colonized plants that were inoculated with the virus after 45 DAC, followed by post-colonized plants that were inoculated with the virus. Nitro blue tetrazolium (NBT) for superoxides and diamino benzidine (DAB) for H2O2 staining recorded a reduction in ROS production in both pre- and post- P. indica-colonized tomato plants artificially inoculated with ToLCV against the virus alone. The decrease in ROS production and disease severity in the fungus colonized plants inoculated with the virus were attributed to the increased total soluble proteins and enhanced activities of antioxidant enzymes. The substantial increase in antioxidant enzymes viz., peroxidase, phosphatase, superoxide dismutase, catalase and glutathione reductase and glutamate synthase were observed in P. indica-colonized plants against the control; and for both pre- and post- P. indica-colonized plants artificially inoculated with ToLCV against the virus alone. Thus, the present study reveals that P. indica can be exploited for the management of ToLCV on prophylactic and curative bases with the best results in the former. P. indica colonized plants enhanced the over all growth and productivity; and drastically reduced the severity of ToLCD under both controlled and open field conditions.
Evaluation of Piriformospora indica against Piper yellow mottle virus in Black pepper
(Department of Plant Pathology, College of Agriculture, Vellayani, 2021) Lekshmi R Krishnan; Joy, M
The study entitled “Evaluation of Piriformospora indica against Piper yellow mottle virus (PYMoV) in black pepper” was conducted in Department of Plant Pathology, College of Agriculture, Vellayani, Thiruvananthapuram during 2019-2021, to evaluate the efficiency of the root colonizing endophytic fungus P. indica in managing PYMoV in black pepper, and to elucidate the role of Reactive Oxygen Species and antioxidant enzymes in the tripartite interaction. A survey conducted in the instructional farm of College of Agriculture, Vellayani, to identify and collect PYMoV-infected black pepper plants showed that the surveyed varieties viz., Panniyur 1 to 7 and Karimunda were moderately to highly susceptible to PYMoV infection, with the disease incidence ranging from 10 to 91 per cent and disease severity as vulnerability index from 30 to 58. PYMoV-infected black pepper plants showed symptoms like chlorotic flecking, mottling, light necrosis, crinkling and distortion of leaves, reduction in leaf size and stunted growth. Presence of the virus in the samples was confirmed by polymerase chain reaction (PCR) with oligonucleotide primers specific to open reading frame III (ORF III) of PYMoV. P. indica culture obtained from Department of Plant Pathology was maintained in potato dextrose agar (PDA) and potato dextrose broth (PDB) media. P. indica was mass multiplied in coirpith-dried farm yard manure (FYM) mixture (1:1) amended with two per cent gram flour and was allowed to colonize on rooted cuttings of black pepper. P. indica colonization enhanced different biometric characters at different intervals, compared to the non-colonized control plants. P. indica colonization resulted in 25 per cent more shoot length, 23 per cent more root length, 35 per cent more number of leaves, 23 per cent more leaf area and 27 per cent more number of primary roots than the control plants at 150 days after co-cultivation (DAC). A pot culture experiment was laid out to evaluate the efficiency of prophylactic as well as curative application of P. indica, in managing PYMoV of black pepper. P. indica colonization significantly reduced the incidence and severity of PYMoD, upon pre- as well as post- inoculation of the virus, compared to the control plants. Plants colonized with P. indica and later inoculated with PYMoV as well as plants infected by PYMoV and later colonized by P. indica, both recovered the loss in biomass caused by the virus infection, compared to the non-colonized plants challenged by the virus. However, prophylactic treatment with P. indica resulted in better control of the disease compared to the curative treatment. Amplification of the virus by PCR also revealed that the virus titer was the least in P. indica-colonized plants that were post-inoculated with the virus after 30 DAC, followed by pre-inoculated plants that were later colonized with P. indica. The virus titer was the highest in the non-colonized plants inoculated with the virus. In order to evaluate the performance of P. indica in modulating the biochemical responses of black pepper plants against PYMoV infection, the activity of various enzymes which are known to play a role in the antioxidant defense systems of plants viz. catalase, peroxidase, glutathione reducatse, glutamate synthase, phosphatase and superoxide dismutase were assayed. A significant increase in the activity of these antioxidant enzymes was observed in the P. indica-colonized plants compared to the control plants, upon pre- as well as post- inoculation of PYMoV. Thus, the better performance of P. indica-colonized plants upon PYMoV infection can be correlated to the increased activities of antioxidant enzymes. PYMoV-infected plants showed increased accumulation of reactive oxygen species like superoxide anions and hydrogen peroxide, which cause oxidative stress in the plants. P. indica-colonization was able to mitigate the increase in ROS concentration caused due to PYMoV infection, thus reducing the symptoms. Thus the study reveals that, co-cultivation of rooted cuttings of black pepper (obtained from disease-free mother plants) with P. indica and keeping them under insectproof conditions for around 30 days (for successful establishment of the fungus inside the root cortex) and then planting them in the main field is a reliable and chemical-free method to control PYMoD in black pepper. Bio-protective action of P. indica might be attributed to the increased activity of antioxidant enzymes, which in turn leads to suppression in ROS accumulation in the colonized plants, upon being challenged by the virus.
Genetic variation in tomato for yield and resistance to bacterial wilt
(Kerala Agricultural University, Vellanikara, 2001) Pradeepkumar, T; Dijee, Bastian; Joy, M; Radhakrishnan, N V; Aipe, K C
Management of banana bract mosaic virus using beneficial fungal root endophyte, Piriformospora indica
(Department of Plant Pathology, College of Agriculture ,Vellayani, 2024-03-20) Sinijadas, K.; Joy, M
The research work entitled “Management of Banana bract mosaic virus using beneficial fungal root endophyte, Piriformospora indica” was carried out at the Department of Plant Pathology, College of Agriculture, Vellayani, Thiruvananthapuram during the academic year 2018-2022. The objective was to evaluate the beneficial fungal root endophyte, P. indica for the management of Banana bract mosaic virus (BBrMV); and to elucidate the role of antioxidants and plastids in this tripartite interaction. The characteristic symptoms of BBrMV viz., reddish spindle shaped streaks on pseudostem, black necrotic streaks on peduncle, chlorotic spindle lesions on leaves and underdeveloped fruits were observed during the survey conducted in five agro-climatic zones (ACZ) of Kerala. Percent disease incidence (PDI) and vulnerability index (VI) of the disease recorded from different zones showed the highest in banana var. Nendran (PDI - 61.66 & VI – 44.03) from southern zone and lowest in var. Poovan (PDI – 7.29 & VI – 6.29) in central zone. Serological and molecular detection confirmed the presence of BBrMV in banana var. Nendran. The sequence similarity analysis of the coat protein (CP) gene of BBrMV southern zone isolate (Vellayani) showed 99.12 percent genetic closeness to its Tamil Nadu isolates compared to the Kerala isolates (98.38 percent). Screening of the most virulent strain of BBrMV from five different ACZ of Kerala was done based on early symptom development in TC banana plants var. Nendran. The BBrMV strain from southern zone could produce the symptoms on var. Nendran within 30 days (lowest) followed by central zone (55 days) on artificial inoculation with viruliferous aphids, Pentalonia nigronervosa. The cross-infection study of virulent strain of BBrMV (southern zone) of Nendran on Nendran developed chlorotic spindle lesions on leaves at 30 days after inoculation followed by Nendran on Robusta (75 days). P. indica-colonization in banana var. Nendran was carried out using standardized medium. The chlamydospores of the fungus were observed in roots at 20 days after colonization (DAC). In both in vitro and in vivo experiments, P. indicacolonized plants showed reduced disease severity irrespective of the virusinoculation stage with a vulnerability index of 6.7 percent in BBrMV (+Pi / +V); and 20.0 percent in the virus-infected plants post-colonized with P. indica (+V / +Pi) compared to 53.3 percent in the virus alone infected plants. Further, PCR analysis with BBrMV coat protein specific primer yielded amplicon of low intensity in P. indica-colonized plants inoculated with the virus compared to the control plants indicating the ability of the fungus to inhibit the virus. Further, P. indica precolonized plants inoculated with BBrMV had improved growth and yield parameters compared to non-colonized plants. Field trial was laid out with two treatments (P. indica-colonized and noncolonized banana plants var. Nendran) at Instructional Farm, College of Agriculture, Vellayani. P. indica-colonized plants recorded a drastic reduction in the severity of BBrMV by 33 to 58 percent compared to non-colonised control plants. Enhanced plant height (30 percent), collar girth (45 percent), number of leaves (25 percent), leaf length (30 percent), leaf width (27 percent), fresh weight of shoot (34 percent), number of secondary roots (62 percent), number of tertiary roots (76 percent) and root weight (86 percent) were observed in P. indica-colonized plants at 90 days after treatment. P. indica-colonization also improved the bunch weight (32.9 percent) and fruit quality. Biochemical detection of superoxides using nitroblue tetrazolium (NBT) and H2O2 with diamino benzidine (DAB) stains at 5, 10, 15, 30 and 45 days revealed a reduction in reactive oxygen species (ROS) accumulation in both P. indica-colonized plants challenged with BBrMV (+Pi / +V) and virus infected plants post-colonized with P. indica (+V / +Pi) compared to BBrMV alone. The decrease in ROS production and disease severity in the endophyte-colonized plants inoculated with the virus were attributed to the increased activities of antioxidant enzymes viz., peroxidase, superoxide dismutase, catalase, glutamate synthase and ascorbic acid oxidase. The molecular analysis of genes involved in the symptom development indicated the beneficial effect of P. indica on BBrMV infection in banana. P. indica reduced the symptoms by up-regulating chlorophyll biosynthesis gene (chlorophyll synthase-CHLG) and down-regulating chlorophyll degradation genes (chlorphyllase CLH1 & CLH2; and pheophytin pheophorbide hydrolase - PPH), carotenoidbiosynthesis genes (phytoene synthase-PSY1 and PSY2), carotenoid degradation gene (Phytoene desaturase - PDS) and the virus specific genes responsible for symptom development (Hc-Pro and P3). Thus, the present study reveals that P. indica enhances tolerance against BBrMV in addition to improved growth promotion, yield and fruit quality in banana plant.
Management of bhendi yellow vein mosaic virus using beneficial fungal root endophyte Piriformospora indica
(Department of Plant Pathology, College of Agriculture, Vellayani, 2020) Chippy; Joy, M
Management of blackeye cowpea mosaic virus using natural products from botanicals and the fungal root endopyte piriformospora indica
(Department of Plant Pathology, College of Agriculture, Vellayani, 2019) Chandran, K; Joy, M
Management of brown spot disease of rice using fungal root Endophyte Piriformospora indica and new generation fungicides
(Department of Plant Pathology, College of Agriculture,Vellayani, 2019) Safana Ashar, V; Joy, M
A study entitled ‘Management of brown spot disease of rice using fungal root endophyte Piriformospora indica and new generation fungicides’ was conducted during 2017-19 at Department of Plant Pathology, College of Agriculture, Vellayani with the objectives to evaluate the effect of root endophyte Piriformospora indica against brown spot disease of rice caused by Helminthosporium oryzae and evaluation of new generation fungicides viz., strobilurins, azoles and their combinationsfor the management of brown spot disease of rice. A survey was conducted in rice fields of six KAU stations during 20182019 to collect the infected leaf samples and to assess the disease incidence (DI) and severity (Percent Disease Intensity (PDI)). Among the surveyed locations, maximum DI (76%) and PDI (64.6%) were recorded from IFSRS Karamana whereas the disease was absent in RARS Kumarakom due to the complete crop failure. H. oryzae was isolated from the collected specimens; a total of five pure cultures of H. oryzae (Isolate 1 to Isolate 5) were obtained and Koch’s postulates were proved for all the isolates in rice var. Uma. All the H. oryzae isolates were screened for its virulence and pathogenicity in rice var. Uma. The isolate 5, from IFSRS Karamana, produced the symptom within 24 h of inoculation. On 5th day of leaf inoculation, isolate 5 recorded maximum PDI of 62.22 per cent with a maximum lesion size of 2.94 cm; and thus concluded as the most virulent isolate. Dual culture assay of P. indica and H. oryzae in potato dextrose agar (PDA) medium indicated that the beneficial root endophytic fungus significantly inhibited the growth of the pathogen through multiple antagonistic properties viz., lysis / inhibition zone (0.65 cm) and antibiosis (0.37 cm). Maximum growth inhibition of H. oryzae (54.44 %) by P. indica was observed on 7th day of dual culturing. P. indica-primed rice seedlings and plants (var. Uma) could significantly delay the symptoms of H. oryzae up to eight days after inoculation (DAI) of the pathogen. The primed seedlings and plants recorded the lowest lesion size (67.87 and 63.6% over control respectively) at seven DAI and the highest disease suppression (87.6 and 80.3 % over control respectively) at 15 DAI. P. indica-root colonization in rice seedlings resulted in enhanced growth with increased root and shoot biomass. P. indica-colonized roots had more number of secondary and tertiary roots with profuse root hairs. There was two-fold increase in shoot and root fresh weight and three-fold increase in shoot dry weight and 2.3 fold increase in root dry weight. The above experiments were done in CRD with five replications. In vitro evaluation of selected new generation fungicides viz., tebuconazole 25.9 EC, difenoconazole 25 EC, azoxystrobin 23 EC, pyraclostrobin 20 WG, pyraclostrobin 20 WG + tebuconazole 18.3 SC, azoxystrobin (11%) + tebuconazole (18.3%) SC at 10, 50,100 and 250 ppm against H. oryzae in PDA by poisoned food technique revealed that all the selected fungicides significantly reduced the growth of H. oryzae. Combination fungicides were more effective in inhibiting the growth of H. oryzae. The highest inhibition was observed in pyraclostrobin 20 WG + tebuconazole 18.3 SC at different concentrations tested; and at 100 and 250 ppm, there was complete inhibition of mycelial growth of the pathogen followed by azoxystrobin (11%) + tebuconazole (18.3%) SC. Based on the results of in vitro evaluation, a pot culture experiment was conducted with rice var. Uma to evaluate the efficacy of the best azole fungicide (tebuconazole 25.9 EC), best strobilurin fungicide (pyraclostrobin 20 WG) and their combinations (pyraclostrobin 20 WG + tebuconazole 18.3 SC and azoxystrobin (11%) + tebuconazole (18.3%) SC at 0.05 and 0.1 per cent against brown spot disease of rice in CRD with three replications. All the tested fungicides significantly reduced the lesion formation and development in leaves. Minimum lesion size of 0.84 cm and 1.17 cm was recorded in azoxystrobin (11%) + tebuconazole (18.3%) SC and pyraclostrobin 20 WG + tebuconazole 18.3 SC respectively. Similarly, the maximum disease suppression of 81.30 per cent and 77.50 per cent over control was recorded with azoxystrobin 11 + tebuconazole 18.3 SC at 0.1% and pyraclostrobin 20 WG + tebuconazole 18.3 SC at 0.05% respectively. The results clearly indicated the curative action of azole, strobilurin and its combination fungicides. Thus, the present study revealed that brown spot of rice could be effectively managed by root colonization of rice seedlings with the beneficial root endophytic fungus, P. indica or foliar spraying of azoxystrobin 11% + tebuconazole 18.3% at 0.1% or pyraclostrobin 20 WG + tebuconazole 18.3 SC at 0.05%. The results may be subjected to multi-location and multi-seasonal field trials before recommendation. The compatibility of P. indica with new generation fungicides and the residue of fungicides in grains may further be studied.
Piriformospora indica and new generation fungicides for the management of Anthracnose incited by Colletotrichum gloeosporioides (Penz.) Sacc. in vegetable Cowpea
(Department of Plant Pathology, College of Agriculture, Vellayani, 2025-03-26) Amrutha, P; Joy, M
An investigation on “Piriformospora indica and new generation fungicides for management of anthracnose incited by Colletotrichum gloeosporioides (Penz.) Sacc. in vegetable cowpea” was carried out at Department of Plant Pathology, College of Agriculture, Vellayani during 2017-2022. The objective was to study the host range of C. gloeosporioides causing anthracnose disease (leaf blight, girdling and blight of stem and fruit rot) of vegetable cowpea and to evaluate the efficacy of fungal root endophyte, P. indica and new generation fungicides for its management. The typical symptoms of vegetable cowpea anthracnose viz., dark brown circular to irregular spots on the leaves, midrib, stems, branches and pods were observed during the survey conducted in ten locations representing five agro-climatic zones (ACZ) of Kerala. The disease severity as percentage disease index (PDI) and disease incidence (DI) recorded from different zones showed a highest from farmers field, Kottarakkara (PDI-73.50 and DI-51%) in southern zone and lowest from RARS, Pattambi (PDI-23.56 and DI-16%) in central zone. The pathogen was isolated on potato dextrose agar (PDA) medium and ten isolates of C. gloeosporioides were obtained. The isolates were named as Cg1 to Cg10. The isolates produced white to grey coloured colonies with regular margin and the conidia appeared cylindrical or straight with round or obtuse apex. Cg1 isolate recorded maximum radial mycelial growth of 9 cm within 7 days of inoculation compared to other isolates. Screening of the most virulent isolate among the ten isolates was done by spraying the spore suspension of the pathogen (106 to 107 cfu ml-1) on to vegetable cowpea var. Vellayani Jyothika and Cg1 produced largest lesion size of 6.56 cm and PDI of 85.94 (most virulent) followed by Cg4 (lesion size-4.56 cm, PDI-65.83); whereas Cg7 was the least virulent isolate (lesion size-0.46 cm, PDI-26.03) at 10 day after inoculation (DAI). Screening of nine vegetable hosts viz., brinjal, cucumber, pumpkin, chilli, tomato, amaranth, winged bean, bean and bush cowpea against Cg1 by detached leaf assay using mycelial bits revealed brinjal as the most susceptible host with a lesion size of 5.9 cm, followed by pumpkin and cucumber (lesion size - 4.9 cm) and the least susceptible host as bush cowpea (1.5 cm) at 7 DAI. Similarly, seven KAU and one IIHR cowpea varieties screened against Cg1 indicated Arka Garima (PDI-76.5) followed by Vellayani Jyothika (PDI-66.06) as the most susceptible varieties and Anaswara (PDI-11.9) as tolerant variety at 10 DAI. Poison food technique and spore germination assay were carried out with triazoles, strobilurins and their combination fungicides at 10, 50, 100 and 250 ppm against Cg1. Trifloxy-strobin 25 % + tebuconazole 18.3 % SC followed by azoxystrobin 11 % + tebuconazole 18.3 % SC and difenoconazole 25% EC at 250 ppm recorded highest inhibition of mycelial growth higher than 88 per cent; whereas, strobilurin fungicide pencycuron 22.9 % SC recorded least inhibition of 18.89 per cent. Hexaconazole 5EC and difenoconazole 25% EC (250 ppm) drastically reduced the spore germination by 97.67 per cent. Compatibility study of P. indica with systemic insecticides and fungicides showed that thiamethoxam 25% WG and flubendiamide 39.35% SC at 250 ppm as the most compatible (62.22% and 61.11%) and chlorpyriphos 20 EC as the least compatible insecticides at 7th DAI; whereas trifloxystrobin 50 WG and trifloxystrobin 25 % + tebuconazole 18.3 % SC at 350 ppm as the most compatible (74.44% and 68.89%) and hexaconazole 5EC and difenoconazole 25% EC (0%) as the least compatible systemic fungicides on 10 DAI. Colonization of P. indica in vegetable cowpea var. Vellayani Jyothika was carried out using dried FYM - coir pith - gram flour amended medium. The roots were examined for colonization at regular intervals. The endophyte started colonising the roots and observed young chlamydospores at 5 days after germination (DAG) and the colonization was high in roots at 15 DAG with mature chlamydospores arranged in chains inside the cortical cells of roots. In both in vitro and in vivo experiments, P. indica-colonized vegetable cowpea plants reduced severity of anthracnose to 77.17 and 62.41 per cent compared to non-colonized plants on 20 and 35 DAI respectively. The beneficial fungal endophyte colonization also improved the shoot and root biomass of the plants at 20 and 35 DAI respectively. P. indica-colonization followed by spraying of systemic fungicides viz., trifloxystrobin 25 % + tebuconazole 18.3 % SC and carbendazim 50 WP drastically reduced the disease severity to 64.44 and 59.1 per cent respectively at 50 day after transplanting (DAT). P. indica-colonization also reduced the residues of trifloxystrobin 25 % + tebuconazole 18.3 % SC (17%) and carbendazim 50WP (16.6%) in the crop. Field trials were laid out with P. indica-colonized and P. indica-non-colonized vegetable cowpea var. Vellayani Jyothika at Instructional Farm, College of Agriculture, Vellayani in two seasons [rabi (2019) and summer (2020)] on natural incidence of anthracnose. P. indica-colonized plants recorded a drastic reduction in severity of the disease (63.21 and 64.47); in addition to cercospora leaf spot (54.81 and 58.7) and Blackeye cowpea mosaic virus (54.16 and 56) in rabi and summer seasons. Enhanced shoot weight (35 and 35.73%), root weight (24 and 25.55%), number of root nodules (22.72 and 23.25%), number of pods (18.96 and 22.02%), length of pods (13.5 and 12.81%), number of flowers (20 and 25.8%), seeds per pod (21.73%), average weight per pod (16.12 and 19.04%) and average yield per plant (35.34 and 36.91%) were observed in P. indica-colonized plants at 90 DAT in rabi and summer. Biochemical analysis of defence enzymes at 0, 12, 24 and 72 hours after inoculation (HAI) showed a significant increase in the activities of chitinase (21.11%) and β, 1-3 glucanase (11.89%) and also total phenolics (4.63%) in plants colonized with P. indica and challenge inoculated with C. gloeosporioides compared to the non colonized plants inoculated with the pathogen at 72 HAI. P. indica-colonization also reduced the accumulation of reactive oxygen species (ROS) which was visualized as dark blue stain of formazan compound; and hydrogen peroxide visualized as dark brown stain; as analysed by nitroblue tetrazolium (NBT) and 3, 3’-diaminobenzidine (DAB) staining respectively. Molecular analysis of genes involved in P. indica-mediated tolerance against anthracnose of vegetable cowpea indicated a downregulation of ROS marker genes (Zinc finger transcription factor (ZAT10), Redox responsive transcription factor (RRTF1), Heat shock protein (HSPRO), O-methyl transferases (OMT) and MYB51) at 12, 24 and 72 h; and upregulation of antioxidant genes (ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR)) at 24 and 72 h by bringing down the programmed cell death. P. indica-colonization also upregulated the expression of abscisic acid signalling genes (Abscisic acid aldehyde oxidase (AAO3-2), Abscisic acid insensitive (ABI 11) and 1-Aminocyclopropane-1-carboxylic acid (ACCS2)) and ethylene signalling genes (ethylene response 1 (ETR 1), ethylene insensitive (EIN1) and ethylene response factor (ERF1)) which are involved in defence responses. Therefore, the present study reveals that brinjal, pumpkin and cucumber are the most susceptible host of C. gloeosporioides causing anthracnose in vegetable cowpea; which implies the restriction of cultivation of the above vegetable crops near to vegetable cowpea. Combination fungicides of triazoles and strobilurins, and triazole fungicides were most effective against C. gloeosporioides. The beneficial fungal endophyte, P. indica was compatible with most of the systemic insecticides and fungicides (except chlorpyriphos and triazoles) used in vegetable cultivation and also reduced their residues in the crop. P. indica-colonization enhanced tolerance against anthracnose, the most important foliar fungal disease, in addition to other fungal and viral diseases with increased growth and yield in vegetable cowpea.
Piriformospora indica- mediated degradation of strobilurin and triazole fungicides in tomato plants
(Department of Plant Pathology, College of Agriculture,Vellayani, 2025) Austin Raj, K S.; Joy, M
The research work entitled “Piriformospora indica-mediated degradation of strobilurin and triazole fungicides in tomato plants” was carried out at the Department of Plant Pathology, College of Agriculture Vellayani, Thiruvananthapuram during 2022-24. The objective was to evaluate the beneficial fungal root endophyte, P. indica on degradation or retention of strobilurin and triazole fungicides used for the management of black leaf mold of tomato. P. indica-colonization in tomato var. Vellayani Vijai was done in the standardized medium. The presence of the chlamydospores was observed in roots of tomato at 5 days after colonization (DAC). P. indica-colonization was further confirmed using fungus-specific primer Pi-tef by PCR. Compatibility of P. indica was studied with fungicides such as azoxystrobin, pyraclostrobin, propiconazole and tebuconazole. P. indica is compatible with azoxystrobin and to some extend with pyraclostrobin; and incompatible with propiconazole and tebuconazole. P. indica exhibited 72 per cent compatibility with azoxystrobin at 50 ppm; while 19.72 per cent compatibility was observed with pyraclostrobin. P. indica could not grow in triazole fungicides, propiconazole and tebuconazole even at 50 ppm. Leaves with characteristic symptoms of black leaf mold of tomato were collected from Coconut Research Station, Balaramapuram. The symptoms were yellow and chlorotic spots on the upper leaf surface and black sooty mold on the corresponding lower surface. The fungus was isolated on potato dextrose agar (PDA) medium. The mycelial growth was grey on the upper side with concentric zonations, and black on the rear side. The margin of the growth was regular. The growth rate was observed as 1.1 mm per day. Koch’s postulate of the pathogen was proved by detached leaf assay. Symptoms started appearing from 5th day onwards. Symptoms were chlorotic lesion on the upper surface and black sooty growth on the lower surface of the leaf. In vitro evaluation of the pathogen against azoxystrobin, pyraclostrobin, propiconazole and tebuconazole was done by poisoned food technique. Both strobilurin and triazole fungicide significantly inhibited mycelial growth of 165 Pseudocercospora fuligena. Triazole fungicides such as propiconazole and tebuconazole were more effective in inhibiting the mycelial growth of P. fuligena than strobilurin fungicides. At 50 ppm, P. fuligena has grown 3.80 cm in azoxystrobin, 3.80 cm in pyraclostrobin, 1.37 cm in propiconazole and 1.21 cm in tebuconazole fungicides. P. fuligena growth was completely inhibited at 100 ppm of triazole fungicides; but at least 25 per cent fungal growth was observed in strobilurin fungicides even at 1000 ppm. A field experiment was conducted during the summer season (2023) at Coconut Research Station Balaramapuram. The first spray of fungicides was given at the vegetative stage ie., 40 days after sowing. The second spray of fungicides was given after fruit set stage ie., 70 days after sowing. The leaves and fruit samples were collected at 2 h, 24 h, 3, 5 and 10 days after spraying and residues were assessed by LC-MS/MS. P. indica enhanced the retention of the fungicide residues in leaves. The fungus also enhanced the degradation of the fungicides in tomato fruits which makes the fruits safer to eat. P. indica-colonization decreased the incidence and severity of diseases such as black leaf mold, Alternaria leaf spot, leaf curl and mosaic under natural incidence. When azoxystrobin was used, 64.05 per cent reduction of black leaf mold severity was observed over control at 60 days after transplanting. When propiconazole was used, 55.49 per cent reduction was observed. When azoxystrobin was used along with P. indica, the disease severity has been further reduced to 71.89 per cent; and when propiconazole was used along with P. indica, a reduction of 69.25 per cent was observed. Moreover, P. indica enhanced the growth parameters such as plant height, number of flowers per plant, number of fruits per plant and average yield per plant. Further P. indica decreased the number of days taken for flowering, 50 per cent flowering, fruit set and 50 per cent fruit set. Molecular basis of P.indica-mediated degradation of strobilurin and triazole fungicides was done at 3 and 7 days after the application of the fungicides. RNA was extracted and reverse transcribed into cDNA. GAPDH was used as the house keeping gene. Expression of genes involved in the degradation of strobilurin fungicides such as strH and Carboxyl esterase and Ergosterol gene involved in the degradation of triazole were studied. P. indica-colonization significantly enhanced the expression of Carboxyl esterase and Ergosterol genes in the fruits, thus increasing the fungicides degradation in fruits; whereas it repressed the expression of strH and Ergosterol genes 166 in leaves, thereby increasing the retention of fungicides in leaves under field conditions. Relative expression of the genes at 7th day after the application the fungicides was less compared to that at 3rd day. P. indica-colonization together with triazole or strobilurin fungicides application could effectively control the black mold disease caused by P. fuligena with enhanced biometric and yield characters of tomato. P. indica-colonization significantly enhanced the retention of the fungicides in leaves by down regulating the fungicide degrading genes; and degradation of fungicides in fruits by upregulating the fungicide degrading genes under field conditions with ecological sustainability and also to produce safe-to-eat tomatoes.
Promising botanicals and piriformospora indica for the management of blackeye cowpea mosaic virus in yard long bean
(Department of plant pathology, college of agriculture, Vellayani, 2023-08-16) Potluri Navya Rohini.; Joy, M
Technology assessment and refinement in coastal homegardens of Kerala: linkages with biodiversity and household livelihoods
(Department of Agricultural Extension Education, College of Agriculture , Vellayani, 2024-01-15) Roshni Thampi; KAU; Allan Thomas; Joy, M
The study entitled “Technology assessment and refinement in coastal homegardens of Kerala: Linkages with biodiversity and household livelihood” conducted from 2019 to 2023 focused on the primary objectives to assess crop diversity, identify the dominance of crops, delineate technology needs, sorter dimensions of technologies and analyze the adoption and technology gaps through action research for sustainable coastal home garden systems. The study also examined the social anthropogenic variables of coastal home garden farmers and explored the linkages between biodiversity and household livelihoods in terms of perceptions and practices by farmers. Constraints in the coastal home garden farming system as perceived by farmers and extension personnel were also studied. The study was conducted in homegardens of three coastal Agro Ecological Units (AEU 1- Southern coastal plains, AEU 3- Onattukara Sandy Plains and AEU 4- Kuttanad) of southern Kerala. 35 farmer respondents were chosen from the home gardens of selected panchayats, comprising 15 participants and 20 non-participants who had at least 25 cents. The total numbers of respondents for the study were 165 comprising 105 coastal home garden farmers, 30 Agricultural Officers and 30 Scientists. Within the framework of Participatory Technology Assessment and Refinement, a collaborative effort was made to select appropriate technology for the primary crops within specific AEUs. This encompassed the evaluation of technology for bittergourd in AEU 1, chilli in AEU 3, and cowpea in AEU 4. Furthermore, Front Line Demonstrations (FLDs) were conducted to showcase and validate KAU-proven technologies that were deemed suitable for these specific crops. The structural configuration in terms of dominance-biodiversity profile of crops in coastal home gardens of southern Kerala was studied under two aspects viz., numerical and economic dominance and the diversity profile of coastal homegardens in Kerala. The study revealed that in AEU 1, out of the 82 identified crops, the most dominant one was coconut (5.90) followed by bittergourd (5.81) whereas in AEU 3 a total of 78 crops were identified, of which the maximum dominance was noted with black pepper (5.65) followed by chilli (5.26). In AEU 4 a total of 85 crops were identified of which the maximum dominance was noted with cowpea (5.24). The study compared the mean diversity index across different AEUs and found that AEU 4 exhibited the highest diversity index at 1.547, followed by AEU 3 at 1.159, and AEU 1 at 1.058. When examining the crop-wise diversity profile of coastal AEUs, fruits had the highest diversity index at 0.998, followed by vegetables at 0.878, and spice crops at 0.850. Conversely, the lowest biodiversity index was recorded for tubers at 0.360 and ornamental plants at 0.357. In AEU 1, the maximum diversity index was observed for spices at 0.801, followed by vegetables at 0.770, and medicinal crops at 0.741, with tubers having the lowest diversity index at 0.350. In AEU 3 and AEU 4, the highest diversity index was noted for fruit crops at 1.181 and 1.164, respectively, while the lowest diversity index was recorded for medicinal plants at 0.225 and 0.226 respectively. One-way ANOVA analysis revealed no significant difference in crop diversity among selected AEUs, but there was a significant difference in crop-wise diversity for plantation crops, multipurpose trees, medicinal plants, tubers, and ornamental plants. In terms of region-wise biodiversity, the mid-regions had the highest diversity index at 1.433, while the courtyard of coastal home gardens had the lowest diversity at 1.117. The study on vertical diversification of crops in different coastal AEUs revealed that in AEU 1 maximum diversification was seen for banana with six levels of diversification whereas in AEU 3 maximum diversification was seen for banana and coconut with five levels of diversification. In AEU 4 the maximum diversification was seen for coconut and banana with four levels followed by cowpea and black pepper with two levels of diversification. The extent of horizontal diversification was also recorded and found that 40 % of the homegardens in AEU 1 had 5 tier diversification whereas in AEU 3, 60 % of the home gardens had 6 tier or more diversification. In case of AEU 4, 73.33% of the homegardens were having 6 and more tiers of diversification. The study revealed that a significant percentage (53.33%) of homegardens in all AEUs had six or more tiers of diversification. This study involved assessing the technology requirements for the top dominant crops in the selected AEUs. The study identified that in AEU 1, the maximum technology need was recorded with production practices of bittergourd (6.83), whereas in AEU 3, the highest technology need was noted with protection practices (leaf curl disease management) in chilli (6.67). In AEU 4, highest technology need was noted for production practices in cowpea (6.50). Based upon the technology needs of the dominant crops in different AEUs, FLDs were conducted in selected three homegardens on production aspects of bittergourd (AEU 1) and cowpea (AEU 4) and protection aspects for chilly (AEU 3). The FLD in all the AEUs of study clearly highlights that scientific approach in farming and correct use of technology in accordance to KAU POP will help the farmer to derive more profit through improved production. The B:C ratio for FLD studies on bittergourd cowpea was found to be higher (1.96 and 1.78) compared to farmers practices (1.37 and 1.42). Research showed that using scientific methods like KAU practices reduced leaf curl disease in chilli by 48.19%, emphasizing the importance of adopting these techniques. The study also examined how farmers adopted KAU practices. It was found that 77.14% of AEU 1 farmers had low adoption, while 74.29% of AEU 4 farmers had high adoption. In AEU 3, 51.43% had low adoption. The study also categorized farmers as innovators (0.95%), early adopters (16.19%), early majority (34.29%), late majority (32.38%), and laggards (16.19%). In the study, a reliable scale was developed to assess technology-related aspects in Kerala's coastal home gardens. The Single ANOVA tool helped choose indicators with a mean value below 4.49, resulting in 26 variables across 8 dimensions. For reliability, the odd-even split-half method was used, yielding a strong correlation of 0.846 for the half-test and 0.917 for the full test. Pearson's correlation coefficients also confirmed the scale's validity by exceeding 0.25 at a 0.05 significance level. The scale was administered to respondents and the results showed that participating farmers perceived economic dimensions (4.62), environmental dimensions (4.30), and psychological dimensions (4.31) as the most important. Non-participating farmers, on the other hand, considered economic dimensions (4.61), psychological dimensions (4.14), and human resource dimensions (4.12) to be significant. Extension personnel, in their evaluation, rated economic dimensions (4.28), human resource dimensions (4.04), and political dimensions (4.03) as the most important factors. Cluster analysis was done for different dimensions for different categories of respondents and it invariably shows interaction effects of different dimensions of technology. The analysis was done using Ward linkage with 26 indicators, representing 8 dimensions of technology in coastal homegardens. For participant farmers 3 clusters were identified. The first cluster comprised of 10 indicators viz., profit, sustainability, technical efficiency, interpersonal relationship, initial cost, bureaucratic support, perception of technology, coordination, supply chain and acquisition of information that showed strong association. The second cluster encompassed 12 indicators that demonstrated proficiency in areas such as credit access, effective decision-making, keen observability, viability, adept resource management, resource recycling capacity, reasonable price expectations, local resource utilization, ready availability, utilization of family labour, dependable delivery reliability, and skilled labour requirements. The third cluster, comprised of four dimensions, exhibited characteristics related to flexibility, strong social networking, effective budgeting abilities, and openness to utilizing open-source technology. Analysis of livelihood assets revealed that social assets scored the highest mean value (239.3) followed by human assets (227.3), physical assets (185.6), natural assets (172.3) and financial assets (176). ANOVA confirmed that there is significant difference between AEUs in case of all assets except human assets and Pearson correlation analysis was conducted to examine the strength and significance of the relationship between these variables. The results showed a moderate positive correlation (r = 0.311, p < 0.05) between total assets and biodiversity. This suggests that as the total assets of the communities increase, the level of biodiversity also tends to increase. The study delved into gender roles within various coastal home gardens, with a focus on dominant crops. In AEU 1, particularly in bittergourd cultivation, men were predominantly engaged in labour-intensive tasks like land preparation (54.29%) and drain preparation (85.71%). Women, conversely, played more active roles in activities such as weeding (51.43%), kitchen gardening (57.14%), and harvesting (51.43%). Both genders actively participated in operations like irrigation (62.86%), plant protection activities (57.14%), and post-harvest tasks (51.43%). In AEU 3, where chilli cultivation was highlighted, men took on tasks like drain preparation (62.86%) and fencing (74.29%), while women were prominently involved in sowing seeds (68.57%), planting seedlings (57.14%), plant protection (57.14%), kitchen gardening (54.29%), harvesting (74.29%), and post-harvest operations (62.86%). Both men and women contributed to activities like applying manure (62.86%) and fertilizers, as well as weeding (54.29%). In AEU 4, centered on cowpea cultivation, men primarily handled land preparation (60%). Interestingly, women took on most responsibilities related to cowpea cultivation including, applying manure (57.14%), sowing seeds (51.43%), planting seedlings (51.43%), applying fertilizer (57.14%), weeding (51.43%), kitchen gardening (57.14%), and harvesting (60%). Both genders were involved in applying irrigation (54.29%). A chi-square test assessed the significance of gender differences in home garden activities, revealing a strong association between gender and agricultural tasks. The calculated chi-square statistic was 192.78, surpassing the table value of 33.92 at a 0.05% significance level, affirming the substantial gender differences in home garden activities. The study identified a total of 22 constraints within coastal home gardens, which were rated by respondents. The most significant challenges reported by coastal home garden farmers were, lack of scientific knowledge (1031) followed by salinity issues (rated at 1010), flooding concerns (1008), ineffectiveness of plant protection methods at recommended dosages (rated at 969), insufficient knowledge about plant protection chemicals (960), the impact of climate change (948), and the absence of proper drainage systems (916), listed in descending order of importance. Key suggestions to improve coastal home gardens as perceived by farmers and extension personnel were, the creation of customized packages of practices tailored to the coastal home garden system, enhanced on-going support and guidance from extension agencies for the adoption of recommended scientific practices and the promotion of Farmer Producer Organizations (FPOs) to enhance post-harvest handling and marketing Social anthropogenic variables of coastal home garden farmers like age, education, gender, occupation, economic motivation, extension contribution, irrigation potential, information source utilization, credit orientation, training need, market orientation and adoption were also studied. In essence, the research revealed a multifaceted profile of dominance and diversity within the coastal home garden community. Furthermore, it outlined specific technology requirements, adoption patterns, and dimensions conducive to the development of coastal home gardens. Additionally, the study delved into aspects related to livelihood assets, gender roles, constraints, and provided valuable suggestions to promote the sustainability of coastal home gardens in the Kerala region.
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; Joy, M