Browsing by Author "Chandrasekharan Nair, M"

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Biological control of Rhizoctonia solani Kuhn on rice using mycoparasites
(Department of Plant Pathology, College of Agriculture, Vellayani, 1989) Viswakumar, P; Chandrasekharan Nair, M
The present investigation was undertaken to assess the effects of mycoparasite-fungicide combinations on the intensity of sheath blight disease, and also the effect of the same on the rhizosphere and phylloplane mycoflora of rice. An attempt has also been made to identify efficient mycoparasites of Rhzoctonia solani naturally present on the rhizosphere and phylloplane of rice plants. Several fungi isolated from the rhizosphere and phylloplane of rice plants were found to exhibit strong antagonistic action against R. solani, in vitro. Antagonistic fungi such as Trichoderma viride, T. harzianum, Aspergillus niger caused granulation, vacuolation and finally disintegration of R. solani hyphae. The ability of the antagonists to produce volatile as well as diffusible metabolites was also assessed. T. viride was found to be very efficient in inhibiting the growth of R. solani, as a result of the diffusible as well as volatile metabolites produced by the fungus. T. harzianum was also very efficient in inhibiting growth of R. solani. When the antagonist T. viride was mass cultured in various growth substrates and tried for their efficacy as potential biocontrol agents of sheath blight disease of rice, rice bran as well as wheat bran turned out to be the best growth substrates. Under pot culture conditions, where the efficacy of various mycoparasite- fungicide combinations in checking sheath blight was assessed, T. viride was the best mycoparasite and edifenphos the best fungicide. The rhizosphere mycoflora was enhanced by application of mycoparasite, especially T. viride and T. harzianum. Among fungicides application of edifenphos resulted in increased rhizosphere mycofloral population. In the case of phyllooplane mycoflora application of mycoparasites have a suppressive effect. Treatments of edifenphos increased phylloplane mycofloral population. Under field conditions also T. viride emerged as the best mycoparasite and ediphenphos as a superior fungicide in checking sheath blight. T. viride + ediphenphos was also found to be very efficient in controlling sheath blight disease. The highest grain and straw yields were obtained in treatment with the mycoparasite T. viride, and fungicide edifenphos. The treatment combination T. viride + edifenphos also gave the highest yield. In the case of rhizosphere mycoflora application of mycoparasites enhanced the population. Mycoparasites were found to have a suppressive effect on the fungal population on the leaf surface.
Changes in free amino acids content of groundnut hypocotyl tissue infected with Sclerotium Rolfsii Sacc
(Kerala Agricultural University, 1977) Anandavally Amma, P; Shanmugam, N; Chandrasekharan Nair, M
Comparative efficacy of certain fungicides in the control of sheath rot of rice
(Kerala Agricultural University, 1981) Chinnaswamy, R; Chandrasekharan Nair, M; Ramanatha Menon, M
Effect of application of plant protection chemicals on the survival of Rhizoctonia solani Kuhn
(Department of Plant Pathology, College of Agriculture, Vellayani, 1986) Lulu Das; Chandrasekharan Nair, M
In Kerala, the incidence of sheath blight of rice is endemic causing great economic loss. The present investigation was undertaken to make a critical assessment of the efficacy of various palnt protection chemicals, viz., fungicides, insecticides and herbicides on the incidence and intensity of sheath blight of rice and on the survival of the pathogen. The organism was isolated from naturally infected rice fields and its pathogenicity proved. Studies on the viability of sclerotia revealed that they sclerotia remained viable upto 210 days in all the different types of soils namely sandy, clayey and loamy. The organism could survive on straw bits upto 180th ady only.
Effect of fungicidal treatments on the germination and microflora of sunflower seeds
(Kerala Agricultural University, 1976) John Abraham, K; Ramanatha Menon, M; Chandrasekharan Nair, M
Effect of hydrolytic enzymes in the pathogenesis of sclerotial root rot of peanut
(Kerala Agricultural University, 1975) Anandavally Amma, P; Shanmugam, N; Chandrasekharan Nair, M
An isolate of Sclerotium rolfsii Sacc. from peanut was found to produce the enzymes endopolygalacturonase (endo-PG) and cellulase (Cxi both in culture as well as in the inoculated peanut hypocotyl tissues. Endo-PG secretion was more during the early stages of growth and pathogenesis. On the other hand high cellulase activity was recorded during advanced stages of pathogenesis and in old cultures. These enzymes were also secreted with cell wall material isolated from the hypocotyl tissues as sole carbon source. The results are discussed as proof of the role of these enzymes in the sclerotial root rot disease of peanuts.
Effect of plant protection chemicals on foliar pathogens and Phylloplane microflora of rice
(Department of Plant Pathology, College of Agriculture, Vellayani, 1989) Gokulapalan, C; Chandrasekharan Nair, M
The present investigation was undertaken to assess the effects of plant protection chemicals on the important fungal pathogens and phylloplane microflora of rice. An attempt has been made to identify potential biological control agents to combat sheath blight disease causing havoc to rice cultivation in Kerala. Both under pot culture conditions and during the course of field trials at two locations viz., Adoor and Karamana, Kerala, the fungicide carboxin was found to be the best treatment for reducing the incidence and intensity of sheath blight and sheath rot diseases of rice. The fungicide was found to be the least harmful to the epiphytic microflora of the rice plant. In some instances the population of phylloplane antagonists of R. solani, including Trichoderma harzianum, T. viride, Penicillium oxalicum and Aspergillus aculeatus were found to be enhanced by the application of carboxin. The total disease incidence and yield loss were significantly reduced by the application of edifenphos. The rice variety Karthika was found to be significantly tolerant to sheath blight and sheath rot compared with the rice variety Jyothy. The fungicides carboxin and mancozeb at 500ppm did not inhibit the growth of the phylloplane antagonists of R. solani viz., Trichoderma harzianum and T. viride under in vitro conditions. Several micro-organisms isolated from the rice phylloplane were found to exhibit in vitro antagonism towards R. solani. These include Aspergillus aculeatus, A. niger, Chaetomium globosum, Penicillium oxalicum, Trichodema harzianum, T. viride, several bacteria and a few basidiomycetous yeasts. The phylloplane antagonists, Trichoderma harzianum, T. viride and Penicillium oxalicum were found to readily parasitise R. solani hyphae leading to coiling, penetration followed by disintegration and death of the mycohost. When these antagonists were cultured on bran and tried for their efficacy as potential biocontrol agents of R. solani, it was found that these fungi could significantly reduce the incidence and intensity of sheath blight of rice, though this was not comparable with the effect of the fungicide carboxin.
Epidemiology and control of sheath rot disease of rice
(Department of Plant Pathology, College of Agriculture, Vellayani, 1986) Krishnakumaran Nair, B; Chandrasekharan Nair, M
Studies on symptomatology, epidemiology and control aspects of sheath rot disease of rice caused by Serocladium oryzae Cams & Hawksworth (= Acrocylindrium oryzae Saw.) were done in detail. The disease initiated as purplish-brown oblong lesions on the sheath of the flag leaf. At maturity lesions enlarged in size with grey -white centres and often covered the entire flag leaf sheath. Panicle often did not emerge but choked inside the affected sheaf itself. Artificial inoculation studies showed that under sufficient humid conditions the pathogen took an average five to eight days for initiation and 15 to 20 days for the complete development of the disease in rice plants. The pathogen was isolated from four naturally infected rice varieties, collected from three different culture (isolates viz., S1, S2, S3, S4, S5, S6 & S7) were selected based mainly on symptomatological variations and their comperative morphological characters were studied in detail. No appreciable differences were noticed in the morphological characters between isolates.
Evaluation of various herbicides on the control of sheath blight disease (Rhizootonia solani Kuhn) on rice
(Department of Plant Pathology, College of Agriculture, Vellayani, 1984) Lakshmy, T R; Chandrasekharan Nair, M
Both in vitro and in vivo studies on the effect of few common herbicides on Rhizoctonia solani and on sheath blight of rice, were carried out. The in vitro studies revealed that Propanil (Stam P.34) vras the most toxic herbicide to Rhizoctonia solani Kuhn, the rice sheath blight pathogen, which completely inhibited nycelial growth at a very low concentration of 125 ppm. Benthiocarb, Nitrofen (Tok E.25) and Butachlor also have high potentiality in decreasing radial growth and also in inhibiting the formation of sclerotia Soil borne sclerotia was found the major source of inoculam in initiating sheath blight diseases. Among the various herbicides tested, Nitrofen, Propanil and Butachlor reduced the degree of pathogenicity of soil borne sclerotia of R. solani* Propanil effected maximum reduction of sheath blight in pot culture experiments followed by Nitrofen. Butachlor and Nitrofen were equally effective in reducing sheath blight under pot culture, experiment. Nitrofen (Tok E.25) applied at 1.5 kg ai, 1.75 leg ai were equally effective as Hinosan in reducing sheath blight in field trial also.
Growth of cylindrocladium quinqueseptajum on different oil incorporated medfa
(Kerala Agricultural University, 1983) Sulochana, K K; Wilson, K I; Chandrasekharan Nair, M
Improvement on the techniques for the cultivation and preservation of tropical species of mushrooms
(Department of Plant Pathology, College of Agriculture, Vellayani, 1994) Balakrishnan, B; Chandrasekharan Nair, M
Intensive collections made from certain selected areas of Kerala yielded a total of eight species of Pleurotus, one species each of Volvariella and Tricholoma, namely V. esculenta and T. lobayense respectively from the native flora. Various species collected were identified and based on the preliminary observations made on their adaptability for large scale cultivation, among the Pleurotus two species have been selected for detailed study along with the other standard cultures procured from various mushroom research centres of the country. The native isolate of T. lobayense in the present study is the first record of the species from Kerala. Detailed studies have been done on various aspects of cultivation of pleurotus spp. With a view to improve the already known technologies so as to suit the conditions of Kerala. The two native species of pleurotus selected have been domesticated and compared with other standard cultures on their performance. Based on the observations made in the seasonal influence, yield and market qualities the species most suited for large scale cultivation in Kerala have been identified. Alternative local substrates for cultivation of oyster mushrooms have been identified and their processing technology standardized. Effective nutritional supplements for increased yield, method for speedy induction of sporocarp, after care method for the once harvested beds for further flushes, effective method for cultivation etc. have been worked out for large scale cultivation of Pleurotus spp. In Kerala. Commonly available low cost substrates in spawn production have been identified and their technologies standardized. Influence of light on spawn growth, influence of storing environment on growth and shelf life of spawn etc. have been studied. Technology for preparation of an instant liquid spawn developed and also a modified method for speedy and low cost production of spawn using polypropylene cover as the container has been standardized. The effect of coconut milk in blending culture media for enhanced growth of various Pleurotus spp. and the effect of coconut milk in their biomass production have been proved. In the strain improvement programme, a substrate influenced mutant of Pleurotus sajor-caju for better yield, a resistant/tolerant strain against the most destructive weed mould Trichoderma viride and an interstock hybrid with desirable traits have been developed. Type of pests and their control etc. have been worked out. The effect of chemical pasteurization of the substrates on checking the weed mould infestation during spawn run and the use of lime powder for spot treatment of beds in the management of T. viride have been proved. Post harvest technology for preservation of both raw and dehydrated forms of mushrooms has been standardized. The native strains of other tropical mushrooms locally collected namely V. esculenta and T. lobayense have been identified based on the detailed description of the same. The performance of the native strain, V. esculenta under cultivation has been compared with that of the standard species, V. volvacea and a technique for cultivation of T. lobayense has been standardized for first time in this part of the country.
Investigation on the edible species of Coprinus and standardisation of techniques for its large scale artificial cultivation
(Department of Plant Pathology, College of Agriculture, Vellayani, 1982) Geetha, D; Chandrasekharan Nair, M
A survey conducted in and around the college of Agriculture, Vellayani Campus revealed that the commonly occurring species of Coprinus were Coprinus lagopus (Fr.) Fr. C.disseiminatus (Pero. ex Fr.) S F Gray and C.ephemorus (Bull.ox Fr.) Fr. and among these, the most commonly occurring species was C.lsgopus. The culture of c.lagopus used for the present study was isolated from paddy straw beds of Volvarlella volvocea raised at the Department of plant Pathology and maintained on potato dextrose agar slants by subculturing periodically.
Leaf blight of Dioscorea Esculenta (Lourd.) Berk.
(Kerala Agricultural University, 1980) Chandrasekharan Nair, M; Karunakaran, P; Gokulapalan, C
Little leaf disease of clove in Kerala
(Kerala Agricultural University, 1980) Karunakaran, P; Chandrasekharan Nair, M
Microflora associated with sunflower seeds
(Kerala Agricultural University, 1976) John Abraham, K; Ramanatha Menon, M; Chandrasekharan Nair, M
Monographic studies on edible species of pleurotus and standardisation of the techniques for large scale cultivation
(Department of Plant Pathology, College of Agriculture, Vellayani, 1987) Suharban, M; Chandrasekharan Nair, M
Mushrooms have long been recognized as a food because of their nutritive value and flavour and hence are grown on commercial scale on many parts of the world. In recent years cultivation of Pleurotus species are becoming popular in many of the tropical areas. No effort has been made in the past to collect, identify, describe and catalogue the Pleurotus mushroom flora of Kerala and standardise the techniques for their large scale cultivation. The present study was therefore initiated to achieve the above objectives. Collection, identification and description of the Pleurotus flora naturally occurred in and around the College of Agriculture and parts of Trivandrum district were carried out with the help of a data sheet. Twenty species of Pleurotus properly identified were further subjected to detailed study. A key was constituted to enable easy identification of gill the twenty described species. Out of the twenty species described, eight species are new records for India. Among the common cultivable species of Pleurotus. P .sajor-caju was found to be the most suitable mushrooms for the warm humid climatic condition of Kerala. The optimum temperature for maximum growth of this mushroom was found to be between 15 to 50 *C. Comparative efficacy of various containers and substrates used for spawn production revealed that Maize and empty wine bottle were the best substrate and container respectively for spawn production. Trials on cultivation of P. sajor-caiu on logs of common trees revealed Mango tree log to be the best in getting higher yield. Polythene bag was found to be the best container in supporting maximum sporocarp formation. Straw of local varieties of rice were better than high yielding varieties of rice in supporting sporocarp, formation. Comparative efficacy of straw made into bits and small twists with six species of Pleurotus revealed higher yield of 775 g per kg of substrate with spawn of Pleurotus- sajor-caju establishing its superiority for cultivation in Kerala. Cultivation of P .saior-caju in different seasons of the year revealed that this mushroom can be successfully cultivated in Kerala all through the year on paddy straw.
New leaf spot of Stylosanthes guianensis due to Colletotrichum Gloeosporioides from India
(Kerala Agricultural University, 1981) Santhakumari, P; Chandrasekharan Nair, M
Observations on the post infectional changes of rice plants infected by the sheath rot fungus (Acrocylindrium oflyzae saw)
(Kerala Agricultural University, 1983) Balakrishanan, B; Chandrasekharan Nair, M
Pathology and control of seed mycoflora of some vegetables in Kerala
(Kerala Agricultural University, 1983) Naseema, A; Balakrishnan, S; Chandrasekharan Nair, M
The survey of the seed mycoflora of certain vegetable seeds viz., amaranthus, bhindi, bittergourd brinjal, cowpea, cucumber, pumpkin, snakegourd and tomato revealed that storage fungi \\keAspargiflusflavus, Aspergil/us riiger and Rhizopus stolonifer were externally as well as internally seed-borne in a/most all the vegetable seeds taken for the study and were found to cause maximum inhibition in germination of the seeds, from which they were isolated. Seedling rotting was caused by Fusarium equiseti on amaranthus, Aspergillus niger on amaranthus and bhindi, Drechslera rostrata on cowpea, and Rhizopus stolonifer on tomato. In vitro evaluation of fungicides showed that Thiride was found to be superior to all other fungicides tested against the seed-borne fungi.
Permeability changes associated with the sclerotial root rot of groundnut
(Kerala Agricultural University, 1977) Anandavally Amma, P; Shanmugam, N; Chandrasekharan Nair, M
Infection of groundnut hypocotyl tissue by Sclerothun rolfsii was found to alter the permeability of host tissue resulting in leaching out of large quantities of water soluble constituents. The culture filtrate of this orgainsm was found to alter cell permeability. The possibility of the enzymes secreted by the impairing pathogen in the host cell permeability is discussed.