Effect of Salinity, Temperature and Carbon Source on the Growth and Development of Sclerotia of Sclerotinia sclerotiorum Isolated from Semi-arid Environment (original) (raw)
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Phytopathology, 2003
Sclerotial germination of three isolates each of Sclerotinia minor and S. sclerotiorum was compared under various Soil moisture and temperature combinations in soils from Huron and Salinas, CA. Sclerotia from each isolate in soil disks equilibrated at 0, -0.03, -0.07, -0.1, -0.15, and -0.3 MPa were transferred into petri plates and incubated at 5, 10, 15, 20 25, and 30degreesC. Types and levels of germination in the two species were recorded. Petri plates in which apothecia were observed were transferred into a growth chamber at 15degreesC with a 12-h light-dark regime. All retrievable sclerotia were recovered 3 months later and tested for viability. Soil type did not affect either the type or level of germination of sclerotia. Mycelial germination was the predominant mode in sclerotia of S. minor, and it occurred between -0.03 and -0.3 MPa and 5 and 25degreesC, with an optimum at -0.1 MPa and 15degreesC. No germination occurred at 30degreesC or 0 MPa. Soil temperature. moisture, or soil type did not affect the viability of sclerotia of either species. Carpogenic germination of S. sclerotiorum sclerotia, measured as the number of sclerotia producing stipes and apothecia, was the predominant mode that was affected significantly by soil moisture and temperature. Myceliogenic germination in this species under the experimental conditions was infrequent. The optimum conditions for carpogenic germination were 15degreesC and -0.03 or -0.07 MPa. To study the effect of sclerotial size on carpogenic germination in both S. minor and S. sclerotiorum, sclerotia of three distinct size classes for each species were placed in soil disks equilibrated at -0.03 MPa and incubated at 15degreesC. After 6 weeks, number of stipes and apothecia produced by sclerotia were counted. Solitary S. minor sclerotia did not form apothecia, but aggregates Of attached sclerotia readily formed apothecia. The number of stipes produced by both S. minor and S. sclerotiorum was highly correlated with sclerotial size. These results suggest there is a threshold of sclerotial size below which apothecia are not produced, and explains, in part, why production of apothecia in S. minor seldom occurs in nature. ABSTRACT Hao, J. J., Subbarao, K. V., and Duniway, J. M. 2003. Germination of Sclerotinia minor and S. sclerotiorum sclerotia under various soil moisture and temperature combinations. Phytopathology 93:443-450.
Effect of Moisture and Temperature on the Survival of Sclerotia of Sclerotium rolfsii in Soil
Journal of Phytopathology, 1988
The sclerotia of Sclerotium rolfsii Sacc. survived in natural soil for 225 days under controlled moisture at 50% water holding capacity (WHC) after which there was a progressive reduction in the population of viable sclerotia. At 390 days only 48% were recovered. Sclerotia survived well at moisture contents upto 75% WHC but at 100% the population declined rapidly and none were recovered after 60 days. The contents of the sclerotia were found to lyse without germination leaving hollow rinds. Such lysis was found to be favoured between 25 and 40°C. At and below 20°C no such lysis was recovered and more than 80% sclerotia were recovered even after 60 days.
Effect of Sclerotial Water Content on Carpogenic Germination of Sclerotinia sclerotiorum
Plant Disease, 2012
The relationship between moisture content and carpogenic germination (CG) of Sclerotinia sclerotiorum sclerotia and the dynamics of sclerotial water imbibition were studied in a controlled environment. The study was conducted using laboratory-produced sclerotia from seven S. sclerotiorum isolates. The quantity and rate of water imbibition by three sizes of sclerotia was determined gravimetrically in silty clay, sandy loam, and sandy soils maintained at 100, 75, 50, and 25% of soil saturation and in distilled water. Smaller sclerotia imbibed water at a significantly faster rate (P = 0.05) than larger sclerotia in water and in soil at all saturation percentages. When buried in soil, small, medium, and large sclerotia were fully saturated within 5, 15, and 25 h, respectively, in all three soil types and moisture percentages. The effect of sclerotia moisture content on CG was evaluated on sclerotia maintained at 95 to 100, 70 to 80, 40 to 50, and 20 to 30% of their water saturation capa...
Population Density of Sclerotinia Species in Various Changes of Climate
World Journal of Agricultural Sciences, 2011
3 Abstract: Fungal pathogens are liable for a wide part of damages in agriculture economy. In the present research a survey was made to study occurrence of Sclerotinia species the causal agent of stem rot in Cauliflower, through agar disc method and dual culture bioassays. The number of apothecia reduced with decrease in temperature and relative humidity. Infection is dependent on long periods of leaf wetness provided by high humidity and high soil moisture and the optimal temperatures are between 15 and 18°C. Thus, control of the disease was targeted by studying the optimal conditions of infection taking Streptomyces with antagonistic properties as biocontrol agent.
Morphological and Patogenic Characterization of Sclerotinia sclerotiorum
Journal of Agricultural Science, 2019
White mold is a disease with a wide distribution worldwide. Temperatures between 18-23 °C and high humidity conditions favor the occurrence of the pathogen. For the control of the disease it is fundamental to understand the morphology and pathogenicity of the fungus. The objective of this study was to characterize the morphological and pathogenic characteristics of Sclerotinia sclerotiorum isolates from the state of Rio Grande do Sul. Sclerodes were disinfested, placed in the center of plates containing culture medium and incubated under controlled conditions. The evaluations were performed daily, during a period of 30 days, from the incubation of sclerotia. The experimental design was completely randomized, with four plaques per isolate, each plate one replicate. The characteristics evaluated for the mycelium characterization were: time required for the fungus to occupy the plate; density of the formed mycelium; coloration of the colonies and mycelial growth rate. Scleroderma a...
Effect of Carbon, Nitrogen sources and Carbon to Nitrogen Ratios on Sclerotinia sclerotiorum
Sclerotinia sclerotiorum is a soil borne plant pathogenic fungus that causative white rot disease in most of vegetable crops, including bean (Phaseolus vulgaris L.). In this study, the effect of different carbon, nitrogen sources and C/N ratios on the growth of S. sclerotiorum were examined. Sclerotia development and sclerotia dry weight were also assayed. The mycelial growth of the fungus was increased with most of carbon sources tested, but the highest levels were found when D-glucose and saccharose were added that produced 1.34 and 1.32 mg/ml mycelial dry weight. Whereas, Lalanine and L-arginin were the best nitrogen sources for the growth of S. sclerotiorum with 0.95 and 0.66 mg/ml mycelial dry weight, respectively. However, ammonium chloride gave moderate growth of the fungus that produced 0.49 mg/ml mycelial dry weight. The best C/N ratios were 9:1 and 20:1 with mycelium dry weight of 1.40 mg/ml in to ratios and 28.75 and 16.25 sclerotium/flask, respectively.
Germinability and virulence of sclerotia of Sclerotium rolfsii were assessed after 50 days of exposure of 14 C-labeled sclerotia to soil at 0, −5 and −15 kPa and pH 6.9, or to soil at 15, 25 or 30 • C, pH 5 or 8 and −1 kPa. Evolution of 14 CO 2 accounted for the greatest share of endogenous carbon loss from sclerotia under all soil conditions, except in water-saturated soil (0 kPa), in which sclerotial exudates contributed the major share of carbon loss. Total evolution of 14 CO 2 from sclerotia in soil at −15 kPa (42.4% of total 14 C) and at −5 kPa (38%) was significantly higher than at 0 kPa (23.8%). Evolution of 14 CO 2 in soil at 25 or 30 • C was more rapid than at 15 • C with regardless of pH. Loss of endogenous carbon by sclerotia was the greater after 50 days of exposure to soil at 0 kPa, or at 25 or 30 • C and pH 8, than at other soil conditions. Sclerotia exposed to water-saturated soil (0 kPa) showed a more rapid decline in nutrient independent germinability, viability and virulence, than to those exposed to −5 or −15 kPa. Sclerotia became dependent on nutrient for germination and lost viability and virulence within 30-40 days in soil at 25 or 30 • C, pH 8. However, more than 60% of sclerotia retained viability in soil at 15 • C regardless of pH, even after 50 days. Radish shoot growth was increased significantly by the sclerotia that had been exposed to soil at 0 kPa, or to soil at 25 or 30 • C and pH 8 for 50 days. In conclusion, carbon loss by sclerotia during incubation on soil at different pH levels, temperatures and water potentials was inversely correlated with sclerotial ability to infect radish seedlings. The relationship between carbon loss by sclerotia and radish shoot length was positive.
Selective Sclerotium cepivorum Growth Agar Media and Other Condition Factors Affecting
Journal of Pure and Applied Microbiology, 2014
New selective medium was used for S. cepivorum growth, forming sclerotia and sclerotial germination. Other affecting condition were evaluated such as pH degree and microelements. Onion bulb-extract at 50% in Potato dextrose agar (OE50PDA) was the best medium for the growth of S. cepivorum gave significant heavy mycelial growth and large numbers of sclerotia. The best growth of the fungus occurred at pH 6.0. Magnesium (Mg), sulfur (S), manganese (Mn) increased the mycelial growth regularity in all concentrations and formed large numbers of sclerotia and achieved significantly sclerotial germination.
Role of air and Light in Sclerotial Development and Basidiospore Formation in Sclerotium Rolfsii
Journal of Plant Protection Research, 2010
Sclerotium rolfsii is one of the devastating soil-borne phytopathogens which causes severe loss at the time of seedling development. It also causes leaf spots in several crops and wild plants. Petri plates, containing potato dextrose agar medium, were inoculated with S. rolfsii. Two-third area of three, 50% area of three and 100% area of other three plates were sealed with cellophane tape.