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

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Author: search.filters.author.Sheela Paul, T

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    Evaluation of newer fungicides against diseases of rice especially rice blast
    (Department of Plant Pathology, College of Horticulture, Vellanikkara, 1981) Sheela Paul, T; Abi Cheeran
    The experiments for the evalution of newer fungicides against rice diseases were conducted at the Rice Research Station and Instructional Farm at Mannuthy during the first and second crop season of 1979-80. The objectives of this study were to find out the efficiency of the new foliar fungicide Panolil, against four rice diseases viz., blast, brownspot, sheath blight and stackburn and to evaluate the efficacy of the newer fungicides Panolil, Panoctine and Panoram as seed treatment fungicides. In the bioassay studies in vitro cent per cent inhibition of Pyricularia oryzae was obtained in 1000 ppm of Panolil, 2000 ppm of Panoctine, 500 ppm of Panoram, 250 ppm of Hinosan and Kitazin and 100 ppm of Agallol in potato dextrose agar medium. In all the fungicide incorporated liquid medium no growth was observed. Panolil (500 ppm), Panoctine (500 ppm), Panoram (1000 ppm), Hinosan (1000 ppm), Kitazin (1000 ppm) and Agallol (100 ppm) completely inhibited the growth of Drechslera oryzae in solid medium. In liquid medium also no growth was observed even in lowest concentration of Panoli, Panoctine and Agallol, 250 ppm and above concentration of Panoram and Kitazin. But growth was observed in all the lower concentrations of Hinosan. Cent per cent inhibition of corticium sasakii was not noticed even in 2000 ppm concentration of Panolil and Panoctine. Panoram and Kitazin at 250 ppm concentration and Hinosan at 500 ppm gave 100 per cent inhibition of C. sasakii. In liquid medium no growth of the fungus was obtained in any of the fungicidal treatments except in the lowest concentration of Kitazin. Panolil, Hinosan and Kitazin gave 100 per cent inhibition of Alternaria padwixkii only at 2000 ppm. Panoram at 1000 ppm and Agallol at 100 ppm gave 100 percent inhibition. In liquid medium growth was observed only in the lowest concentration of Panoram and Kitazin and in all the concentrations of Hinosan. The incidence of blast was low in both the seasons and in both the varieties. Two higher concentrations of panolil (1.5 kg/ha and 1 kg /ha) were equally effective as organophosphorus fungicides in reducing leaf infection, while against neck blast, Hinosan and Kitazin were better than Panolil. Brown spot disease was low in both the varieties during first crop and while in second crop season disease was notices only in Jaya. Panolil 1.5 kg/ha was found to be superior to Hinosan and Kitazin in reducing the disease. Sheath blight infection was low and was noticed only during the first crop in the variety Triveni. Panolil was as effective as organophosphorus fungicides in controlling the disease. Stackburn disease appeared on both the varieties in both the seasons. This disease was best controlled by higher concentrations of Panolil. Seed treatment and storage studies were conducted using the seeds collected from the first crop season. Newer fungicides panolil, Panoctine and Panoram and Agallol were used as seed treatment fungicides. The effect of delayed drying and storage, on seed microflora and deterioration of viability were also studied by using the seeds treated with different fungicides. An increased number of fungal flora was observed in untreated seeds compared to the treated ones. Generally the number of seeds associated with fungal flora increased on storage. For both rice varieties Agallol was found to be the best in reducing association of fungal flora on seeds while when the storage period was extended upto 32 weeks the highest concentration of newer chemicals were found to be on par with Agallol. When the seeds were stored for 16 weeks, the influence of delayed drying on germination was pronounced only when the drying was delayed beyond 6 days then the germination fell below 80 per cent. After 24 weeks of storage, the germination fell below 80 per cent even when the drying was delayed for three days. Agallol was found to be the best seed dresser, followed by the higher concentrations of newer fungicides. When the storage was prolonged for 32 weeks, satisfactory germination was obtained only for the seeds dried immediately and pretreated with Agallol and Panoram 1 g/kg and 1.5 g/kg.
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    Biochemical and biological bases of resistance in solanaceous vegetables against bacterial wilt incited by Ralstonia solanacearum (Smith) yabuuchi etal.
    (Department of Plant Pathology, College of Horticulture, Vellanikkara, 1998) Sheela Paul, T; James Mathew
    An investigation on biochemical, biological and nutritional bases of resistance in solanaceous vegetables against bacterial wi1t incited by Ralstonia solanacearum (Smith) Yabuuchi et al., has been attempted. The pathogen R. solanacearumwas isolated from respecti ve hosts and characterised by various morphological, cultural, biochemical and physiological tests upto biovar level. The three isolates were cross inoculable, and were sensitive to AmDistryn and Streptocycline. Based on these studies the tomato and chilli isolates were identified as Ralstonia solanacearum race I biovar III and that from brinjal as R. solanacearum race I biovar V. The study on toxigenic property of the bacterial isolates revealed that the toxic metabolites were not host specific. Out of the 43 varieties / lines screened , 12 varieties / lines were selected, one each from resistant, moderately resistant, moderately susceptible and susceptible categories. The varieties / lines selected were LE 79-5, BT-IO, LE 470 and Pusa Ruby for tomato; Swetha, Composite-2, BB-7 and Pusa Purple Long for brinjal and Ujwala, Manjari, Jwalasakhi and Pusa Jwala for chilli. The studies on biochemical, biological and nutritional factors in tomato, brinjal and chilli showed considerable variation between crops, between varieties/ lines, and between plant parts. However the root being the primary foci of infection by R. solanacearum the biochemical reactions in root is considered more important than other plant parts. Among the biochemical factors, the OD phenol and specific activity increased due to infection and the content was higher in the resistant genotype (LE 79-5) both under heal thy and diseased condition in tomato. In brinj al, the polyphenol oxidase activity, specific activity and peroxidase activity increased due to infection and were higher in resistant genotype (Swetha) both under healthy and diseased condition. In chilli, total phenol and OD phenol, increased due to infection and were higher in resistant plants (Ujwala) under healthy and diseased condi tions. The soluble sugar content and specific activity were also higher in resistant plants both under healthy and diseased condition even though a decrease was observed due to infection . In tomato, the resistant genotype showed a higher content of OD phenol, polyphenol oxidase activity, specific activity and alkaloids under healthy condition; and total phenol, OD phenol, soluble protein, specific activity and peroxidase activity under diseased condition. In brinjal, the resistant genotype recorded higher content of total phenol, OD phenol, soluble sugars, amino acids, soluble protein, polyphenol oxidase activity, specific activity and peroxidase activity under healthy condition; and polyphenol oxidase activity, specific activity and peroxidase activity under diseased condition. In chilli, the resistant genotype recorded higher total phenol, OD phenol, soluble sugars and specific acti vi ty under heal thy condition; and total phenol, OD phenol, soluble sugars, specific activity and peroxidase activity under diseased condition. Among the biological factors, the total microflora (fungi and actinomycetes), Pseudomonads and parasitic nematodes increased due to infection in resistant genotype whereas beneficial microbes recorded a decrease in population in resistant genotype by infection. In tomato the resistant genotype recorded higher nematode population under heal thy condi tion and higher total microflora, virulent Ralstonia and avirulent Pseudomonas under diseased condition. In brinjal the resistant genotype recorded higher population of fungi, avirulent Pseudomonas, mycorrhiza and saprophytic nematodes under heal thy condition, and fungi, virulent Ralstonia, avirulent Pseudomonas and nematodes under diseased condition. In chilli, the resistant genotype recorded higher populations of avirulent Pseudomonas, mycorrhiza and nematodes under heal thy condition and fungi, avirulent Pseudomonas and mycorrhiza under diseased condition. Among the nutritional factors, in tomato the resistant genotype recorded higher content of potassium and calcium under heal thy condition and iron, zinc and manganese under diseased condition. In brinjal the resistant genotype recorded higher content of nitrogen, calcium, magnesium and zinc under heal thy condition; and potassium, magnesium, iron and zinc under diseased condition. In chilli, the resistant genotype recorded higher content of phosphorus, calcium and iron under heal thy condition; and nitrogen, potassium magnesium and zinc under diseased condition. Thus the study revealed that it was not possible to arrive at common bases for resistance to bacterial wilt in tomato, brinjal and chilli taken together. However it was possible to outline the important parameters that conditions resistance in individual crops.