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“Studies on plant resistance against sheath blight of rice caused by Rhizoctonia solani Kühn.”

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Title “Studies on plant resistance against sheath blight of rice caused by Rhizoctonia solani Kühn.”
M.Sc. (PLANT PATHOLOGY)
 
Creator Persaud, Rajendra
 
Contributor Thrimurty, V.S.
 
Subject diseases, rice, planting, developmental stages, sowing, fungi, biological phenomena, application methods, biological development, grain
 
Description The present investigation entitled “Studies on plant resistance against sheath blight of rice caused by Rhizoctonia solani Kühn” was carried out in field experimental site and green house of the Department of Plant Pathology, Indira Gandhi Agriculture University, College of Agriculture, Raipur, (C.G.). The present studies conducted includes (1) the crop growth stage and disease progress, (2) disease impact at different growth stages, (3) identification of slow disease developing varieties, (4) the role of antagonists, (5) the efficacy of resistance imparting chemicals and (6) the influence of sheath blight on seedling vigour. The present investigation revealed that the tillering crop growth stage was found to be the most susceptible stage of the rice plant to sheath blight (Rhizoctonia solani) followed by the maximum tillering, booting and finally panicle emergence / duff crop growth stage. Infection at the different growth stages have no significant effect on the panicle length. The number of filled grains were significantly more in healthy plant panicle (check) than any of the inoculated crop growth stage plant panicles. Similarly significantly less number of unfilled grains were recorded in the healthy plant panicles than any of the inoculated plant panicle treatments at different growth stages. Out of the 38 varieties / entries screened under artificial inoculated condition for the slow disease developing ability if any, the over all percent disease severity over the observation period ranged from 5.65 to 48.61, with the lowest percent disease severity obtained in Rasi and the highest in CN 1266-9-6. The area under the disease progress curve was lowest for variety VL-30029 and highest progress in disease development was recorded in R 1831-RF-16.
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The mean apparent infection rate at the exponential growth stage (i.e., the rate of disease development between two observation dates / timing) ranged from 0.0285 (RP 4353-MSC 28-13-3-1-1-3) to 0.1982 (Rasi). In varieties RP 4353-MSC 28-13-3-1-1-3, SJR 38 and so on which showed a continuous decrease in rate of development which also indicates that the host resistance might have played a role in restricting the rate of disease development. In a separate trial conducted out of the 39 rice varieties / breeding materials that were evaluated under natural conditions (i.e., no artificial inoculation) 2 varieties, R-1249-1440-3-1 and R-1240-927-3-1056-1 showed no disease symptom which were followed by Shyamala (4.36 %) and the highest percentage disease severity was recorded as 48.23 % in Badsha Bhog followed by R-1238-692-820-1-1, Purinima, Danteshwari and P-44-BR. The application of antagonistic organisms showed no significant differences among the treatments (P = 0.05) at any the stage of observation. However, they could reduce the disease severity and control treatment had the maximum disease severity, followed T1 (Pseudomonas fluorescenes @ 2 g / liter), and T3 (Bacillus subtilis @ 2grams / litre). The Pseudomonas fluorescenes when applied @ 3 g / liter reduced the disease severity in comparison to all the treatments, and was followed by T4 (Bacillus subtilis @ 3grams / litre). The antagonists could reduce the disease severity to some extent and their efficacy may depend due to several factors. The maximum number of filled grains per panicle and 1000 - grain weight were obtained in T2 (Pseudomonas fluorescenes applied @ 3 g/litre) when compared to the other treatments. In general the control treatment showed the least 1000 -gram weight. The salicylic acid and oxalloacetic acid could reduce the severity of the disease and more so in the 200 ppm. Also the number of filled grains per panicle increased and 1000-grain increased as the concentration of the chemicals increased, and on the other hand, the number of half filled and unfilled (chaffy) grains per panicle decreased. In both chemicals, salicylic acid and oxalloacetic acid, the rate of 200 ppm gave the superior results.
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The percent germination, root length, shoot length and seedling vigor index were significantly higher in both varieties (Pant- 4 and Swarna) in the healthy plant seeds (T1) as compared to the diseased plant seeds (T2), in both trials conducted under the green house (pot) and field conditions and also at both observation (21 and 30 DAS).
 
Date 2016-09-22T10:49:08Z
2016-09-22T10:49:08Z
2009
 
Type Thesis
 
Identifier 141p.
http://krishikosh.egranth.ac.in/handle/1/78295
 
Language en
 
Format application/pdf
 
Publisher INDIRA GANDHI KRISHI VISHWAVIDYALYA, RAIPUR