Browsing by Author "Ravi, S"

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Agave Americana - a new host of Phytophthora palmivora (Butler) butler
(Kerala Agricultural University, 1987) Beena, S; Ravi, S; Wilson, K I; Estellitta, S
Calcium and phosphorus requirements of indigenous layer ducks (Anas platyrhynchos)
(Department of Poultry Science, College of Veterinary and Animal Sciences, Mannuthy, 2002) Ravi, S; Peethambaran, P A
A 3 x 3 factorial experiment was carried out at the Department of Poultry Science, Kerala Agricultural University during the period from February to July 2002 to establish the optimum requirements of calcium (Ca) and available phosphorus (AP) in the diets for indigenous layer ducks under cage system of rearing. The Kuttanad varieties of indigenous ducklings of Kerala were maintained on deep litter system of rearing until 18 weeks of age at the University poultry farm, Mannuthy. From this flock, Ninety (90) female ducks were housed in 45 California type cages at the rate of two ducks per cage and they were weighed individually at 20 weeks of age. The dimension of each cage was 60 x 45 x 40 cm and the floor area of 1350 cm2 per duck was provided in the cage. The experimental diets were fed from 21 to 40 weeks of age and the observations were recorded in five periods of 28 days each. Nine experimental diets containing three levels of Ca viz., 3.0, 3.5 and 4.0 per cent with three levels of AP viz., 0.40, 0.50 and 0.60 per cent were formulated and were fed to nine treatments consisting of five replicates of two ducks per cage in each treatment in a 3x3 factorial design. The mean body weight of ducks at 20 weeks of age was uniform III all groups ranging from 1400±9.11 to 1465±53.24 g with an overall mean of 1431±9.96 g. The Ca and AP levels did not influence significantly the 40th week body weight, which ranged from 1473±18.10 to 1579±58.28 g with an overall mean of 1544± 13.7 6g. The age at first egg in the flock with 3.0, 3.5 and 4.0 per cent Ca levels were 154, 158 and 148 days respectively and with AP levels 0.4,0.5 and 0.6 per cent the same were 161, 154 and 148 days respectively. The period wise mean duck housed number (DHN) from 25-40 weeks of age (18.1eggs) was significantly higher with ducks fed 4.0 per cent Ca (P<0.05). The interaction effect was significant (P<0.05) for the dietary combination of 4.0 per cent Ca and 0.6 per cent AP with 20.2 eggs. The cumulative egg number (EN) of 75.7 eggs from 21 to 40 weeks of age was also higher with the Ca level 4.0 per cent and the 71.9 per cent production with diet T9 was superior by interaction effect (P<0.05). The duck housed per cent (DHP) production from 25 to 40 weeks of age averaged 64.6±1.92 per cent with 4.0 per cent Ca level. The Ca and AP levels in the diet did not influence the mean daily feed consumption, feed conversion ratio (FCR), egg mass and shell thickness. The overall mean daily feed consumption was 137.2±1.49 g per duck. The FCR per dozen eggs was 2.8±0.078 and that per kg egg was 3.9±0.099 for the period from 25 to 40 weeks of age. The mean egg weight (EW) and per cent shell were highly significant and the EW of 60.1±0.575 g averaged with 3.0 per cent Ca and 0.5 per cent AP level as well were high (Pinteraction effect with the above combination was also significant (PThe 9. 7±0. 081 per cent shell recorded with 0.5 per cent AP was significantly lower in comparison with other AP levels (P<0.05). At 40 weeks of age, the overall mean serum Ca was 15.42±0.35 mg/dl and serum P was 3.18±0.081 mg/dl. The mean serum inorganic P value of 2.92±0.164. mg/dl recorded with dietary Ca level 4.0 per cent was significantly lower than that of 3.5 per cent Ca level (P<0.05). The tibia ash (62.34±0.512 per cent) was significantly higher with 0.6 per cent dietary AP level (P<0.05) and the tibia ash Ca with 4.0 per cent dietary Ca level was significantly higher and the interaction effect with 0.6 per cent AP level was also significant. With this AP level, the tibia P was reduced significantly, but the interaction showed that the tibia P was high with diet T9. The liveability was excellent in ducks reared in cages (100 per cent) and there was no mortality during the period from 21 to 40 weeks of age. In the present study, the production traits used for evaluating the Ca and AP requirements of caged layer ducks were EN, EW, egg mass, feed consumption and FCR. The study revealed that 4.0 per cent Ca in the diet was superior over other Ca levels in the diet. The dietary Ca and AP levels did not influence the mean daily feed consumption and feed conversion ratios significantly. On the other hand, dietary AP levels influenced the mean EW, per cent shell, tibia ash weight and tibia ash Ca and P. Though the mean EW of 60.1±O.566 g recorded with 0.5 per cent AP was significantly higher, the significant interaction on egg number with the 0.6 per cent AP with 4.0 per cent Ca was found superior. Therefore it will be logical to set the requirements of AP at 0.6 per cent level. Thus, the overall results of the present study revealed that the 4.0 per cent Ca and 0.6 per cent AP levels with 18 per cent Crude Protein and 2650 Kcal ME/kg was optimum for egg production in indigenous layer ducks under cage system of rearing.
Epidemiology and management of black rot of cauliflower in plains of kerala
(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2011) Lakshmi Prasanna, S; Ravi, S
The present study “Epidemiology and management of black rot of cauliflower in plains of Kerala” was taken up at Department of Plant Pathology, College of Horticulture, Vellanikkara and Agriculture Research Station, Mannuthy during 2009-2011 with an aim to study the epidemic factors influencing the incidence, development and severity of black rot caused by Xanthomonas campestris pv. campestris in plains of Kerala and to conduct field studies on its management. The pathogen was isolated from the leaves and curds of cauliflower showing typical symptoms of the disease, on PSPA medium. The colonies of the isolate were yellow in colour, circular, slimy and smooth convex with entire margin. Studies on morphological, cultural and biochemical characters confirmed the bacteria as Xcc. Various types of viz., chlorotic lesion, V shaped lesions, vein blackening; necrosis and vascular discoloration were produced by the pathogen. The symptoms were initially localized and later became systemic and stunting of plants was noticed due to systemic infection. Progression and severity of the disease was studied by inoculating the plants at five days interval starting from 10 days after transplant (DAT) up to 60 DAT. Cauliflower plants of all age group were found to be susceptible to this disease. But, young plants were succumbing to death due to infection. As the age increased there was gradual decrease in the systemic infection. Plant mortality also decreased with the increase in age at which they got infected. Sixteen cauliflower varieties were screened for black rot disease under field conditions. The incidence, calculated as A- value (AUDPC), varied from 0.53 to 12.81. These varieties were grouped in to four categories based on the scale; 0-resistant, 0-3 moderately resistant, 3-5 moderately susceptible and >5 susceptible. Out of sixteen varieties, none was found to be resistant, eight were found to be moderately resistant, two were moderately susceptible and remaining six were susceptible. An attempt was made to formulate a score card for this disease for easy observation and which has a bearing on the yield. The actual area of infection in the leaf at 10, 25 and 40 days old plants were correlated with yield and a equation y=389.061+3.371(10 DAT)-0.986(25 DAT)-2.391(40 DAT) was obtained. Three system of score card were formulated and their relationships with the yield were re-correlated statistically and three additional equations were arrived. The equation two was comparable with the original equation and that score card can be better adopted as it showed 95 per cent similarity to the original, where scale 1 and 3 showed 77.5 and 90.1 per cent similarity respectively. An attempt was made to determine the role of weather parameters on incidence of this disease. The weather factors such as maximum temperature and sunshine hours were positively correlated prevailing to the observation on 9th day and average of 7, 8 and 9 days. Similarly average of 4, 5, 6; 5, 6, 7 and 6, 7, 8 days were positively correlated with only sunshine hours. A partial multiple regression equation is also derived for predicting the disease incidence. Such correlation studies have to be conducted for at least five years consecutively to arrive at a better prediction model. Initial in vitro evaluations were done to identify the chemicals, botanicals and bioagents to be carried to the field. Field trail showed that garlic extract 10 per cent, tetracycline 250 ppm and Pseudomonas fluorescens were best treatments against Xcc.
Necrotic streak - A symptom of kokkan disease of banana
(Kerala Agricultural University, 1992) Ravi, S; Vilasini, T N; Beena, S; Abi Cheeran
New bacterial wilt of Coleus Vettiveroides Jacob
(Kerala Agricultural University, 1992) Estelitta, S; Beena, S; Koshy Abraham; Ravi, S; Varadarajan Nair, P
Witches' broom disease of Stachytarpheta indica Vahl.
(Kerala Agricultural University, 1987) Ravi, S; Sally K Mathew; Abi Cheeran