Evaluation of damping-off tolerance in spinach cultivars in field soils and in a standardized lab assay with Pythium ultimum

2021 ◽  
Author(s):  
Kim Magnée ◽  
Joeke Postma ◽  
Steven Groot ◽  
Gerrit Gort ◽  
Edith Lammerts van Bueren ◽  
...  
Keyword(s):  
Pythium Ultimum ◽  
Cultivar Differences ◽  
Control Treatment ◽  
Damping Off ◽  
Fresh Market ◽  
Chemical Treatments ◽  
History Of ◽  
Water Holding ◽  
Prevalent Pathogen ◽  
Evaluation Of Damping

Spinach growers face increasing problems of damping off in the production of fresh market (baby-leaf) spinach due to increasing restrictions on chemical treatments. Damping-off tolerant cultivars are increasingly important, requiring proper evaluation methods. From three locations in the Netherlands with a history of spinach cultivation and from one location in France, potential damping-off pathogens were isolated from the soil, identified to species or genus, and tested for their pathogenicity. Pythium ultimum was the most prevalent pathogen in those fields, causing spinach pre- and post-emergence damping off. Eight spinach cultivars with two or three seed lots each, were evaluated at the same field locations and in a greenhouse with soil sampled from one of the Dutch field sites. Pre-emergence damping off was more discriminating for differences among the cultivars than post-emergence damping off. Variation in levels of infection among trials, replicates, and seed lots of same cultivars, emphasized the need for a more standardized phenotyping assay. For such an assay, a cornmeal/sand-based inoculum with a pathogenic P. ultimum isolate was added to a substrate mixture of sand, perlite, and vermiculite, moistened until 50% water holding capacity, in which spinach seeds were incubated for ten days in a dark climate cabinet at 15°C, including a control treatment without P. ultimum inoculum. The assay showed reproducible results for discriminating differences in pre-emergence damping-off tolerance levels among seed lots. However, cultivar differences in pre-emergence damping-off tolerance levels could not be confirmed due to a large variation among seed lots that needs further investigation.

scholarly journals The effect of guava (Psidium guajava) leaf extract on the quality of cobia (Rachycentron canadum) fillets during ice storage

2021 ◽  
Vol 13 (Aquaculture) ◽  
pp. 52-63
Author(s):  
Minh Phu Tran ◽  
Thi Kim Duyen Huynh ◽  
Le Anh Dao Nguyen ◽  
Thi Nhu Ha Nguyen ◽  
Quoc Thinh Nguyen ◽  
...  
Keyword(s):  
Thiobarbituric Acid ◽  
Psidium Guajava ◽  
Control Treatment ◽  
Ice Storage ◽  
Thiobarbituric Acid Reactive Substances ◽  
Rachycentron Canadum ◽  
Sensory Property ◽  
Ice Water ◽  
Water Holding

The aim of this study is to evaluate the effects of Psidium guajava leaves extract on the quality of cobia (Rachycentron canadum) fillets during in ice storage. A group of cobia fillets was soaked in Psidium guajava extract solutions at concentration of 0.03% (w/v) for 30 minutes while the other group soaked in cold ice water, considered as control treatment. The experimental fillets were packed and stored in ice for 15 days. Sampling were done on the 1st, 5th, 10th and 15th day. Analyzed parameters included temperature, total viable counts (TVC), sensory property, pH, moisture, water holding capacity (WHC), texture, total volatile base nitrogen (TVB–N), peroxide value (PV), Thiobarbituric acid reactive substances (TBARs), and fillet color. The results indicated that cobia fillets treated with guava extract solutions 0.03% showed significantly higher sensory property, lower PV and TBARs compared to the control treatment during ice storage. Based on the sensory property and total viable counts, cobia fillets can be used up to 10 days in both treatments remaining high quality of the cobia fillet.

Gliovirin, a new antibiotic from Gliocladium virens, and its role in the biological control of Pythium ultimum

1983 ◽  
Vol 29 (3) ◽  
pp. 321-324 ◽  
Author(s):  
Charles R. Howell ◽  
Robert D. Stipanovic
Keyword(s):  
Pythium Ultimum ◽  
Similar Efficacy ◽  
Antibiotic Activity ◽  
Infested Soil ◽  
Damping Off ◽  
Potato Dextrose Broth ◽  
Seedling Disease ◽  
X Ray ◽  
Gliocladium Virens ◽  
Induced Mutant

A compound with antibiotic activity toward Pythium ultimum was isolated from potato dextrose broth shake cultures of Gliocladium virens, a common soil mycoparasite known to inhibit but not parasitize P. ultimum. The mass spectrum and an X-ray crystallograph of the purified antibiotic indicated that it was a new diketopiperazine, and we have given it the trivial name gliovirin. Gliovirin is highly toxic to P. ultimum but is inactive against other fungi associated with cotton seedling disease. The antibiotic does not persist in nonsterile soil where it is apparently inactivated by the soil microflora.An ultraviolet light induced mutant of G. virens deficient for gliovirin production was overgrown by P. ultimum in culture and did not protect cotton seedlings from damping-off in P. ultimum infested soil. A mutant with enhanced gliovirin production was more inhibitory to P. ultimum in culture than the parent isolate and showed similar efficacy as a seedling disease suppressant, even though its growth rate was reduced when compared to the parent isolate. These results indicate that gliovirin may be important to the antagonist–pathogen interaction.

Change in infiltration characteristics associated with cultivation history of soils in south-eastern Queensland

Soil Research ◽  
1997 ◽  
Vol 35 (6) ◽  
pp. 1341 ◽  
Author(s):  
R. D. Connolly ◽  
D. M. Freebairn ◽  
B. J. Bridge
Keyword(s):  
Hydraulic Conductivity ◽  
Crop Production ◽  
Soil Water Storage ◽  
Soil Infiltration ◽  
Soil Matrix ◽  
South Eastern ◽  
History Of ◽  
Plough Layer ◽  
Water Holding ◽  
Soil Groups

Change in soil infiltration characteristics with cultivation can result in reduced soil water storage, increased runoff and erosion, and reduced crop production. We measured changes in infiltration characteristics associated with years of cultivation for 5 soil groups in south-eastern Queensland. Soils were grouped according to soil type and texture into Sodosols, light and heavy Vertosols, Red Ferrosols, and Red Chromosols/Kandosols. Soil infiltration characteristics were determined from measurements of permeability and water-holding properties of the cultivated layer (0–0·1 m deep) and the layer immediately below the plough layer (0·1–0·2 m deep). A rainfall simulator was used to measure the hydraulic conductivity of surface seals and infiltration of bare, tilled soil in the field. Hydraulic conductivity of the soil matrix and macropores and water-holding properties of the 0·1–0·2 m layer were measured with disc permeameters and pressure plate apparatus. Hydraulic conductivity of surface seals decreased exponentially in all soil groups with period of cultivation; half of the decline occurred within 2–6 years of first cultivation. Hydraulic conductivity, macroporosity, and moisture characteristic of the 0·1–0·2 m layer were similarly affected by longer periods of cultivation in all but light-textured soils. Cultivation of light-textured, hardsetting soils (18% clay) did not adversely affect hydraulic conductivity or macroporosity of the 0·1–0·2 m layer and the loosening effect of tillage was somewhat beneficial for the water-holding properties of this layer. The low hydraulic conductivities of the surface or 0·1–0·2 m layer after long periods of cultivation reduced infiltration of rainfall in the field.

Fate of14C-EPTC in a Soil Exhibiting Accelerated Degradation of Carbamothioate Herbicides and Its Control

Weed Science ◽  
1989 ◽  
Vol 37 (3) ◽  
pp. 434-439 ◽  
Author(s):  
Abraham Tal ◽  
Baruch Rubin ◽  
Jaacov Katan ◽  
Nadav Aharonson
Keyword(s):  
Methyl Bromide ◽  
Laboratory Experiments ◽  
Soil Microorganisms ◽  
Inhibitory Effect ◽  
Soil Sterilization ◽  
Soil Disinfestation ◽  
Herbicide Degradation ◽  
Chemical Treatments ◽  
Accelerated Degradation ◽  
History Of

Laboratory experiments were conducted to determine the fate of14C-EPTC in a soil that had a history of vernolate application and exhibited accelerated degradation of carbamothioate herbicides compared to nonhistory soil. A very rapid mineralization of the herbicide to14CO2was evident in history soil, compared to nonhistory soil. The two soils did not differ in the amounts of the EPTC lost through volatilization or in the nonextractable radioactive fractions. Except for small quantities of EPTC-sulfoxide and sulfone, no other metabolites were detected. Degradation of14C-EPTC, as determined by evolution of14CO2in history soil, was drastically inhibited following soil sterilization by means of autoclaving or gamma irradiation. Soil disinfestation by solarization, methyl bromide, or metham had a pronounced inhibitory effect during the first 6 days, but was less effective than sterilization. Treatment of a history soil with the fungicide 2-methoxyethylmercury chloride and dietholate strongly inhibited EPTC degradation, while thiram and fentin acetate had only short lasting effects. Cycloheximide, an antifungal antibiotic, had little effect on the degradation of EPTC while chloramphenicol, an antibacterial antibiotic, inhibited the herbicide degradation. These results indicate that accelerated degradation of EPTC is linked to the activity of soil microorganisms, e.g. bacteria, and can be controlled by sterilization and chemical treatments.

Restructured Pork from Hot Processed Sow Meat: Effect of Encapsulated Food Acids

1985 ◽  
Vol 48 (11) ◽  
pp. 965-968 ◽  
Author(s):  
JOSEPH C. CORDRAY ◽  
DALE L. HUFFMAN
Keyword(s):  
Tensile Strength ◽  
Lactic Acid ◽  
Water Holding Capacity ◽  
Objective Analysis ◽  
Control Treatment ◽  
Reaction Products ◽  
Total Meat ◽  
Restructured Pork ◽  
Water Holding ◽  
Sodium Acid Pyrophosphate

Encapsulated food acids were used in the manufacture of cured, restructured pork from pre-rigor sow meat. The four treatments were: (a) control, (b) sodium acid pyrophosphate (SAP), (c) sodium acid pyrophosphate plus encapsulated lactic acid (LA), and (d) sodium acid pyrophosphate plus encapsulated glucono-delta-lactone (GDL). Sodium acid pyrophosphate was included in three of the treatments in this study because of its ability to catalyze the curing reaction. Products were manufactured from timmings ground through a 3.2-mm plate on a plate grinder and tenderized muscle chunks ground through a 10-mm plate which were blended together in a ratio of 50:50. No significant differences existed among treatments for percent fat (P>0.05). According to sensory panels, the SAP and GDL treatments were rated as having a more intense flavor than the control treatment (P<0.05). Objective analysis revealed no difference in shear value, tensile strength, water-holding capacity, cooked yield or chilled yield. Significantly more of the total meat pigment was converted to nitroso-hematin in the GDL treatment as compared to the control treatment (P<0.05).

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