Browsing by Author "Sukumara Varma, A"

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Antibiotic producing and antagonistic microorganisms in the forest soils of Kerala
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1988) Vinod, P B; Sukumara Varma, A
The antibiotic producing and antagonistic fungi, actinomycetes and bacteria in the evergreen forest soils of Ladysmith forest of Thariyode in Wynad, and Cheriyakanom forest of Thekkadi in Idukki districts of Kerala State were studied. The phanerogamic flore around the sites of soil sample collection in both localities were identified. The total microbial population was studied in relation to the depth of soil. The microbial population was maximum in the top layer and decreased with increase in depth of soil. The total microbial population was higher in Idukki and in both districts, population of bacteria was maximum followed by actinomycetes and fungi. A diversified group of fungi consisting, Mucor, Syncephalastrum, Trichoderma, Microascus, Cunningphamella, Absidia, Aspergillus, Penicillium, Talaromyces, Paecelomyces and Fusarium was present. Three types of actinomycetes viz. Streptomyces sp. with straight sporophores, flexuous sporophores and fascicled sporophores were present while four types of bacteria viz., B. subtilis. Bacillus sp. identical to B. subtilis, Bacillus sp. with small cell and fast growth in NA and Bacillus sp. with small cell and slow growth in NA were present. Antagonistic properties of the isolated were studied with the test organisms Pythium myriotylum, Phytophthora palmivora and Rhizoctonia soleni. Mucor sp. and Cunninchamella elegans showed intermingling and overgrowth with all the test organisms while Absidia corymbefera, Syncephalastrum racemosum, Aspergillus meleus, A. tarreus, Microascus cinereus and Fusarium oxysporum showed this character with P. myriotylum and P. palmivora. Intermingling and overgrowth character was observed in Paecelomyces lilacinus with P. palmivora and R. solani whereas A. versicolor and three species of streptomyces showed this character only with P. palmivora. Mutual inhibition on contact was exhibited by Talaromyces wortmannii with all the three test organisms, while A. versicolor and Streptomyces spp. with flexuous sporophores and fascicled sporophores showed this character with P. myriotylum and R. solani. This character was observed in case of A. corymbefera, S. racemosum, A. meleus, M. cinereus, F. oxysporum and Streptomyces sp. with straigtht sporophores, with R. solani while P. lilacinus showed this with P. myrootylum. Mutual inhibition at a distance was shown by Penicillium citrinum, P. simplicissimum, B. subtilis and the other three Bacillus spp. when tested with P. palmivora and R. solani, but A. terreus showed this reaction only with R. solani. Inhibition at a distance and disintegration of test organism was shown by A. niger with P. myriotylum and R. solani while P. citrinum and P. simplicissimum showed this character only with P. myriotylum. All the three spp. of Trichoderma showed die – back and disintegration of all the three test organisms, while A. niger showed this character only with P. palmivora and A. sydowii showed this character with R. solani only. streptomyces sp. with straight sporophores, B. subtilis and the other three Bacillus spp. showed this character with P. myriotylum alone. Inhibitory properties of antagonists using cell free culture filtrates were estimated and found that A. niger inhibited 100 per cent growth of all the three test organisms while P. citrinum, P. simpliciccimum and B. subtilis showed 100 per cent inhibition of P. myriotylum and a range of 67-87 per cent in case of P. palmovora and R. solani. A. terreus did not inhibit P. myriotylum and P. palmivora, but inhibites 78 per cent of R. solani. All the three Trichoderma spp. moderately inhibited all the three test organisms (13-26 per cent) while A. sydowii showed 20 per cent inhibition of R. solani only. Antibiotic property of the antagonists was determined and P. citrinum exhibited maximum, equivalent to 325 ppm tetracycline followed by Streptomyces with straight sporophores having 250 ppm. T. longibracheatum, P. simplicissimum and A. versicolor recovered antibiotic property equivalent to 150 ppm tetracycline hydrochloride while the other isolates had < 100 ppm equivalence of tetracycline hydrochloride.
Biocontrol of rhizome rot of ginger (Zinfiber officinale) by antagonistic microorganisms
(Department of plant Pathology, College of Horticulture, Vellanikkara, 1996) Shanmugham, V; Sukumara Varma, A
Cyclea peltata - a new host of phytophthora palmivora (butler) butler
(Kerala Agricultural University, 1996) Estelitta, S; Sukumara Varma, A; Vilasini, T N; Vimi Louis; Raji, P
Detection of Ralstonia solanacearum race 3 causing bacterial wilt of solanaceous vegetables in Kerala, using random amplified polymorphic DNA (RAPD) analysis
(Kerala Agricultural University, Vellanikara, 2003) Deepa, James; Girija, D; Sally K, Mathew; Nazeem, P A; Babu, T D; Sukumara Varma, A
Nine strains of Ralstonia solanacearum (Smith) Yabuuchi et al. isolated from bacterial wilt affected plants of brinjal, chilli and tomato in three different agroclimatic zones of Kerala were compared based on the utilization of carbohydrates, hypersensitivity reaction on capsicum leaves and RAPD analysis. Among these, six isolates were grouped into Biovar III and three, into Biovar IIIA. The isolates belonged to Races 1 and 3. RAPD analysis with 10 decamer primers revealed a high degree of polymorphism among the isolates. The primer OPF 8 yielded a unique band of 1.45 kb size for Race 3. This could be considered as a marker for rapid identification of Race 3 isolates of R. solanacearum.
Fruit rot of bitter gourd
(Kerala Agricultural University, 1980) Sukumara Varma, A; Abi Cheeran; Peethambaran, C K
Fungal diseases of selected medicinal plants of Kerala
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1991) Sukumara Varma, A; Abi Cheeran
Hirsutella Thompson II var. Synnematosa Samson, Mccoy & O'donnell on coconut mite aceria (Eriophyes) guerreronis (Keifer) - a new report from India
(Kerala Agricultural University, 1999) Pathummal Beevi, S; Beena, S; Sukumara Varma, A; Lyla, K R; Maicykutty P Mathew; Nadarajan, L
Influence of VAM inoculation on nutrient uptake, growth, yield and bacterial wilt incidence in tomato (Lycopersicon esculentum Mill.)
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2002) Raji, P; Sukumara Varma, A
Management of pumpkin mosaic using selected medicinal plant extracts
(Department of Plant Pathology, College of Horticulture,Vellanikkara, 2003) Vimi Louis; Sukumara Varma, A
"Management of pumpkin mosaic using selected medicinal plant extracts" was undertaken in the College of Horticulture, Kerala Agricultural University, Vellanikkara, Thrissur during 1998-2002. Selection of suitable medicinal plant having antiviral property to pumpkin mosaic virus (PMV), isolation of the inhibitory principle present in the medicinal plant, management of pumpkin mosaic using the plant extract and partial purification and serological studies of PMV were the objectives of the study. Symptomatology, transmission, host range and electron microscopy of PM V were also studied. The symptomatology of pumpkin mosaic was studied by observing the development of symptoms in naturally infected as well as artificially inoculated pumpkin plants. The symptoms appeared as typical mosaic mottling with light and dark green patches in the leaf lamina. This was followed by blistering and malformation of leaves into filiform or some other shapes and resulted in reduction of leaf area. The infected plants were stunted, flowered very sparingly with less number of female flowers and reduced fruit setting. The fruits were often malformed . The virus could be transmitted mainly through sap and vector, Aphis gossypii. The virus found to be weakly transmitted also through seeds. The inoculation of PMV on host plants of four families viz., cucurbitaceae, solanaceae, fabaceae and caricaceae showed systemic infection in water melon, snake gourd, bitter gourd, winter squash,' wild ash gourd (cucurbitaceae) chilli, datura (solanaceae), soybean, cow pea (fabaceae) and papaya (caricaceae). Electron microscopic studies revealed the presence of flexuous virus particles (700-800 x 11 nm) in infected leaf sample. Antiserum was raised against the virus and used for serodiagnostic work. The antiserum showed serological relationship with poty viruses infecting snake gourd, bitter gourd, wild ash gourd, cowpea, soybean, chilli and papaya. DAC- ELISA procedure was standardized and used for detection of PM V from pumpkin. The inhibitory property of extracts of five medicinal plants namely Basella alba, Glycyrrhiza glabra, Phyllanthus fraternus, Plumbago rosea 'and Thespesia populnea were studied-against PMV by pre-inoculation application on pumpkin seedlings. The medicinal plant extracts were prepared using different extraction media viz., chloroform, distilled water, ethyl acetate and petroleum ether at different dilutions. The inhibitory property varied with extraction media and dilution used. The PMV inhibitory property of different parts of Plumbago viz., tender leaf, mature leaf, tender stem, mature stem and root were studied at different temperatures and found that all parts showed inhibitory property which varied with temperature. The root extract which showed the maximum inhibitory property at 30°C (near to room temperature) was used for further studies. The effect of Plumbago on vector transmission was studied by applying the extract before acquisition feeding and inoculation feeding of Aphis gossypii, the vector of PMV. Application before inoculation feeding was found to be effective than acquisition feeding and the inhibitory effect decreased with time after application. Distilled water extract of Plumbago was separated through silica gel column to isolate the inhibitory fraction and found that individual fractions were not effective as plant extract as such against PMV. The inhibitory effect of Plumbago water extract one per cent, on artificially inoculated and healthy pumpkin seedlings was tested by weekly, fortnightly, monthly, bimonthly and single application. Weekly spray was effective to reduce disease severity of artificially inoculated and naturally infected pumpkin seedlings. Delayed incidence of the mosaic and enhanced yield of infected plants was also resulted due to weekly spray of the extract. Enzyme, protein, chlorophyll and phenolics estimation revealed that Plumbago extract spray favoured the resistance and thereby suppression of symptoms. The DAC-ELISA of field samples showed the lower concentration of the virus in Plumbago treated plants.
Microflora of dried spices
(Kerala Agricultural University, 1973) Balagopal, C; Joseph Bagyaraj, D; Sukumara Varma, A; Nair, E V G
New report on the biological suppression of cyst nematode, heterodera oryzicola (Rao & Jayaprakash, 1978) infecting banana (Musa Aab cv. Nendran) in Kerala, India
(Kerala Agricultural University, 2000) Job S K Charles; Vijayalakshmi, A V; Sukumara Varma, A; Chitra Radhakrishnan
Observations on some common species of alternaria with special reference to the influence of substrate on size of conidia
(Division of Plant Pathology, Agricultural College & Research Institute, Vellayani, 1967) Sukumara Varma, A; Sam Raj, J
Cultural, physiological and pathogenicity studies of Alternaria species causing leaf spot disease on seven different host plants have been made. of these Hibiscus Rosa-sinensis is a new record for Alternaria in India. All the isolates grew and sporulated on the different solid media tried. But grouth and sporulation on potato dextrose agar were found to be uniformly good.Minimum radial growth of all the isolates was obtained on their respective host leaf extract agar media. Sporulation was also satisfactory in this media. The isolates from Basella and on onion showed pigment production on Czapek's agar medium
Purification and serology of banana bunchy top virus
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1998) Estelitta, S; Sukumara Varma, A
Banana is one of the major fruit crop in Kerala and is often affected by the bunchytop disease caused by banana bunchytop virus. The disease is easily spread through infected suckers, which are used as the planting materials. Secondary spread is also seen through banana aphid, Pentalonia nigronervosa. Though field level quarantine measures may check the spread of the disease, rapid and convenient methods for the detection and identification of the virus in the suckers as well as in micropropagated plants have not been developed. In this background a study was designed and carried out to purify the BBTV, to produce antisera for developing a serological technique for the pre-symptomatic detection of virus in the planting materials of banana. Studies were also conducted to identify the type of nucleic acid of the virus and its morphology by direct electron microscopy. The study revealed that the disease incidence was maximum during August-November. The virus was not mechanically transmitted and tissue culture plants were the most susceptible planting materials for aphid transmission. Basic studies of virus-vector relationship were also conducted and the adult aphids were found to be effective vectors. In purification studies, among the different portions of banana plants used, the midribs of younger leaves yielded high concentration of the virus. Tissue culture plants yielded more virus concentration than other planting materials. Electron microscopy of the purified BBTV preparation revealed isometric particles of 18-22 nm size. Nucleic acids extracted from both healthy and infected samples were compared. The bands obtained were sensitive to DNase 1 and SI nuclease but not to RNase A, confirming the nucleic acid BBTV as ssDNA. SDS-PAGE analysis of BBTV coat protein revealed that it contained a major protein component of Mr 21000 with Rf value between that of β lactoglobulin (Mr 18400) and α chymotrypsinogen (Mr 25700). Antiserum of BBTV was produced in the rabbit and used for detection of virus specific antigens in different parts of the plant (midrib, petiole, leafsheath and rhizome) by chloroplast agglutination, agar gel diffusion, tube precipitation and ELISA. Among these methods ELISA was found to be highly sensitive for identification of the virus.
Symptomatology and etiology of little leaf disease of pepper (piper nigrum L.)
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1995) Sree Kumari, P K; Sukumara Varma, A
Wilt of Vanilla planifolia A
(Kerala Agricultural University, 1974) Balagopal, C; Indrasenan, G; Bhavani Devi, S; Sukumara Varma, A